Escitalopram

Mechanism

Amiodarone is a class III antiarrhythmic, and its SmPC describes QT prolongation as a direct pharmacological effect of the drug. Class IA and III antiarrhythmics open the list of examples in both SSRI labels. The escitalopram SmPC contraindicates any QT-prolonging drug alongside it: the ban is written broadly, and the classes in brackets are examples.

Symptoms

QTc prolongation on ECG, palpitations, dizziness, syncope. The end point is polymorphic ventricular tachycardia of the torsade type progressing to ventricular fibrillation. The risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, decompensated heart failure and in women.

Management

The pair sits in the escitalopram SmPC contraindications, so the question is which drug stays, not how far to cut the dose. Amiodarone washes out over weeks, so spacing the two drugs apart does not work: QT stays prolonged long after the last dose. Before any decision, potassium and magnesium are corrected and an ECG with QTc is recorded.

Mechanism

The escitalopram SmPC (AEMPS, sections 4.3 and 4.5) lists tricyclic antidepressants among QT-prolonging drugs and contraindicates their concomitant use. The combination has not been studied, and an additive effect on repolarisation cannot be excluded. Two more mechanisms sit on top of QT. Serotonergic: the amitriptyline SmPC calls for caution with SSRIs because of serotonin syndrome. Kinetic: amitriptyline is metabolised mainly through CYP2D6 and CYP2C19, escitalopram inhibits CYP2D6, and tricyclic levels rise. The amitriptyline label does not name escitalopram among potent CYP2D6 inhibitors, but the Lexapro label reports a direct tricyclic experiment: escitalopram 20 mg/day raised desipramine Cmax by 40% and AUC by 100%.

Symptoms

Serotonin syndrome: agitation, confusion, tremor, myoclonus, hyperthermia, tachycardia. QT prolongation on ECG up to torsade de pointes. The amitriptyline label singles out marked bradycardia, decompensated heart failure and electrolyte disturbance (hypokalaemia, hyperkalaemia, hypomagnesaemia) as the vulnerable situations. As amitriptyline levels rise, its dose-dependent effects grow stronger: dry mouth, constipation, urinary retention, orthostatic hypotension, confusion in older patients.

Management

The escitalopram label files this combination under contraindications, so ECG monitoring and dose reduction do not settle it, and one of the two drugs goes. Where a tricyclic is already running alongside a CYP2D6 inhibitor, the amitriptyline label describes monitoring tricyclic plasma levels and adjusting the dose. The two regulators diverge. The FDA Lexapro label stops at caution and monitoring, the AEMPS SmPC files the combination under contraindications, and the severity here follows the stricter European document. For neuropathic pain NICE CG173 puts four drugs in the first line – amitriptyline, duloxetine, gabapentin and pregabalin – so dropping amitriptyline leaves three. Duloxetine among them is serotonergic too.

Mechanism

Escitalopram prolongs the QT interval in a dose-dependent way (escitalopram summary of product characteristics, SmPC, Spanish Agency of Medicines and Medical Devices, AEMPS). According to its own SmPC, atomoxetine can also prolong QT, which is listed among its adverse reactions. In a dedicated study, the corrected QT interval (QTc) rose slightly as atomoxetine concentrations increased, although at the expected peak concentrations it did not differ from placebo (atomoxetine SmPC, AEMPS). The liver breaks down atomoxetine through the enzyme CYP2D6, which escitalopram inhibits. Escitalopram doubled the plasma concentrations of desipramine and metoprolol, two other substrates of this enzyme (SmPCs of both drugs, AEMPS). With the strong CYP2D6 inhibitors fluoxetine and paroxetine, atomoxetine exposure rose 6- to 8-fold. The US Food and Drug Administration (FDA) describes the effect of escitalopram on this enzyme as modest, and no study has tested this exact pair (atomoxetine and escitalopram FDA labels). The atomoxetine SmPC reports serotonin syndrome when atomoxetine was combined with selective serotonin reuptake inhibitors, the group escitalopram belongs to (atomoxetine SmPC, AEMPS).

Symptoms

QT interval prolongation itself causes no symptoms and shows only on the electrocardiogram (ECG). Torsade de pointes, a form of ventricular tachycardia, causes palpitations, dizziness and fainting. With escitalopram, such arrhythmias were reported mainly in women and in people with low potassium, a pre-existing long QT interval or other heart disease (escitalopram summary of product characteristics, SmPC). Higher atomoxetine concentrations raise the risk of its adverse reactions, with larger rises in heart rate and blood pressure (atomoxetine label, US Food and Drug Administration, FDA). Serotonin syndrome presents with agitation, tremor, muscle jerks and fever (escitalopram SmPC).

Management

The combination is contraindicated. The escitalopram summary of product characteristics (SmPC) forbids its use with other drugs that prolong the QT interval (escitalopram SmPC, Spanish Agency of Medicines and Medical Devices, AEMPS). According to its own SmPC, atomoxetine can prolong QT (atomoxetine SmPC, AEMPS). The US Food and Drug Administration (FDA) labels are softer: they carry no QT contraindication and ask for caution when escitalopram is combined with drugs broken down by the enzyme CYP2D6 (escitalopram FDA label). Escitalopram is also contraindicated in people with a history of QT prolongation or congenital long QT syndrome (escitalopram SmPC, AEMPS). If both drugs are still taken, correct low potassium and magnesium before starting escitalopram. In stable heart disease, consider an electrocardiogram (ECG) before the start. If signs of arrhythmia appear, stop escitalopram and record an ECG (escitalopram SmPC, AEMPS). With CYP2D6 inhibitors, atomoxetine may need a slower titration and a lower final dose. If an inhibitor is started or stopped after the atomoxetine dose has been set, reassess response and tolerability (atomoxetine SmPC, AEMPS). Measure pulse and blood pressure before starting atomoxetine, after each dose change and at least every 6 months (atomoxetine SmPC, AEMPS). If serotonin syndrome appears, stop escitalopram and the serotonergic drug at once and start symptomatic treatment (escitalopram SmPC, AEMPS). In this case, the atomoxetine SmPC advises reducing the atomoxetine dose or stopping it, depending on severity (atomoxetine SmPC, AEMPS).

Mechanism

Azithromycin is a macrolide, and its SmPC records prolonged cardiac repolarisation and QT with a risk of ventricular arrhythmia and torsade. The escitalopram SmPC contraindicates any QT-prolonging drug alongside it: the ban is written broadly, and the classes in brackets are examples.

Symptoms

QTc prolongation on ECG, palpitations, dizziness, syncope. The end point is polymorphic ventricular tachycardia of the torsade type progressing to ventricular fibrillation. The risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, decompensated heart failure and in women.

Management

The pair sits in the escitalopram SmPC contraindications, so the question is which drug stays, not how far to cut the dose. A short azithromycin course tempts one to leave things as they are, but the SSRI ban carries no exception for course length. Potassium, magnesium and QTc are checked before the start, and the antibiotic is swapped if they are off.

Mechanism

Ciprofloxacin is a fluoroquinolone, and its SmPC lists concomitant QT-prolonging drugs among the risk factors that call for caution. The escitalopram SmPC contraindicates any QT-prolonging drug alongside it: the ban is written broadly, and the classes in brackets are examples.

Symptoms

QTc prolongation on ECG, palpitations, dizziness, syncope. The end point is polymorphic ventricular tachycardia of the torsade type progressing to ventricular fibrillation. The risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, decompensated heart failure and in women.

Management

The pair sits in the escitalopram SmPC contraindications, so the question is which drug stays, not how far to cut the dose. Ciprofloxacin's cardiac effect is weaker than moxifloxacin's, yet the SSRI ban makes no exception for weaker effects. Urinary tract infections have replacements outside the fluoroquinolones.

Mechanism

Escitalopram is the S-enantiomer of citalopram, the same molecule in purified form. Taking both stacks the dose of one substance, and with it the dose-dependent QT prolongation. The escitalopram SmPC contraindicates any QT-prolonging drug alongside it: the ban is written broadly, and the classes in brackets are examples.

Symptoms

QTc prolongation on ECG, palpitations, dizziness, syncope, with torsade at the far end. Serotonin syndrome is tracked separately: agitation, confusion, tremor, myoclonus, sweating, hyperthermia. Arrhythmia risk is higher with hypokalaemia, hypomagnesaemia and bradycardia.

Management

The pair sits in the escitalopram SmPC contraindications, so the question is which drug stays, not how far to cut the dose. This pair in a prescription list means an error rather than a regimen: usually the same drug has been written under two brand names. One is kept, and no washout is needed when switching between them, since the substance is the same.

Mechanism

Clarithromycin is a macrolide, and its own SmPC puts concomitant drugs associated with QT prolongation among its contraindications. The escitalopram SmPC contraindicates any QT-prolonging drug alongside it: the ban is written broadly, and the classes in brackets are examples. Clarithromycin inhibits CYP3A4, a minor metabolic path for escitalopram, so a small rise in antidepressant levels comes on top of the additive QT.

Symptoms

QTc prolongation on ECG, palpitations, dizziness, syncope. The end point is polymorphic ventricular tachycardia of the torsade type progressing to ventricular fibrillation. The risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, decompensated heart failure and in women.

Management

The pair sits in the escitalopram SmPC contraindications, so the question is which drug stays, not how far to cut the dose. Both labels carry the ban, so the antibiotic course is planned not to overlap with the antidepressant. H. pylori eradication and respiratory infections have macrolide-free regimens.

Mechanism

Dronedarone is a class III antiarrhythmic. Its SmPC describes a QTc increase of about 10 ms as its own effect and separately contraindicates torsade-inducing drugs alongside it. The escitalopram SmPC contraindicates any QT-prolonging drug alongside it: the ban is written broadly, and the classes in brackets are examples.

Symptoms

QTc prolongation on ECG, palpitations, dizziness, syncope. The end point is polymorphic ventricular tachycardia of the torsade type progressing to ventricular fibrillation. The risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, decompensated heart failure and in women.

Management

The pair sits in the escitalopram SmPC contraindications, so the question is which drug stays, not how far to cut the dose. The ban runs both ways: the dronedarone label contraindicates torsade-inducing drugs, the SSRI label contraindicates QT-prolonging ones. Before either drug starts, potassium, magnesium and QTc are checked.

Mechanism

Fluconazole prolongs QT by directly blocking the Ikr potassium current, in the words of its SmPC, which also contraindicates QT-prolonging drugs metabolised through CYP3A4. The escitalopram SmPC contraindicates any QT-prolonging drug alongside it: the ban is written broadly, and the classes in brackets are examples. Kinetics adds a second layer: fluconazole inhibits CYP2C19, the main metabolic path for escitalopram, so antidepressant levels rise along with its dose-dependent QT effect.

Symptoms

QTc prolongation on ECG, palpitations, dizziness, syncope. The end point is polymorphic ventricular tachycardia of the torsade type progressing to ventricular fibrillation. The risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, decompensated heart failure and in women.

Management

The pair sits in the escitalopram SmPC contraindications, so the question is which drug stays, not how far to cut the dose. In superficial mycoses topical forms give almost no systemic absorption and the question disappears. In systemic mycosis an echinocandin is chosen. Switching to another azole does not lift the contraindication: the fluconazole SmPC links QT prolongation to other azoles as well. If the pair continues, potassium, magnesium and QTc stay under watch.

Mechanism

Haloperidol is a typical antipsychotic, and its own SmPC outright forbids giving it with QTc-prolonging drugs. The SSRI labels name it as their antipsychotic example. The escitalopram SmPC contraindicates any QT-prolonging drug alongside it: the ban is written broadly, and the classes in brackets are examples.

Symptoms

QTc prolongation on ECG, palpitations, dizziness, syncope. The end point is polymorphic ventricular tachycardia of the torsade type progressing to ventricular fibrillation. The risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, decompensated heart failure and in women.

Management

The pair sits in the escitalopram SmPC contraindications, so the question is which drug stays, not how far to cut the dose. The ban stands on both sides, and parenteral haloperidol carries more risk than oral. If an antipsychotic is needed, the question is settled on that side, not by trimming the antidepressant dose.

Mechanism

Escitalopram (SSRI) raises synaptic serotonin. Linezolid reversibly inhibits MAO. Co-administration sharply amplifies serotonergic transmission. The FDA boxed warning applies to all SSRIs paired with linezolid.

Symptoms

Serotonin syndrome: agitation, confusion, tremor, myoclonus, hyperreflexia, dilated pupils. Autonomic features: profuse sweating, tachycardia, hypertension, fever above 38.5 °C. Severe cases progress to seizures, rhabdomyolysis, disseminated intravascular coagulation, and death. First signs appear within hours of concurrent dosing.

Management

The combination is not prescribed. Stop escitalopram at least 2 weeks before linezolid. If urgent antibiotic therapy is needed, use vancomycin, daptomycin, or ceftaroline based on susceptibility.

Mechanism

Methylene blue (methylthioninium chloride) inhibits monoamine oxidase (MAO). The US Food and Drug Administration (FDA) escitalopram label classes intravenous methylene blue as an MAO inhibitor, and the FDA methylene blue label cites literature describing it as a potent reversible inhibitor of this enzyme. Escitalopram blocks serotonin reuptake. Together they can cause severe, sometimes fatal serotonin syndrome (methylene blue labels). No reports involved other routes of methylene blue, such as oral tablets or local tissue injection (FDA escitalopram label).

Symptoms

Serotonin syndrome. Mental status changes: agitation, hallucinations, delirium, coma. Autonomic signs: tachycardia, labile blood pressure, dizziness, sweating, flushing, fever. Neuromuscular signs: tremor, rigidity, myoclonus, hyperreflexia, incoordination. Seizures, nausea, vomiting and diarrhoea may occur. Some reported cases were fatal (FDA methylene blue label).

Management

The combination is contraindicated: the US Food and Drug Administration (FDA) escitalopram label contraindicates escitalopram with MAO inhibitors and starting it in a patient who is receiving intravenous methylene blue. The methylene blue labels approved by the European Medicines Agency (EMA) and the FDA say to avoid it in patients taking selective serotonin reuptake inhibitors. If a patient on escitalopram needs methylene blue, stop escitalopram before it is given (FDA escitalopram label). When methylene blue cannot be avoided, give the lowest possible dose and observe the patient for nervous system effects for 4 hours (methylene blue labels). Monitor the ECG and blood pressure during and after the infusion (EMA methylene blue SmPC). If signs of serotonin syndrome appear, stop methylene blue and escitalopram and start supportive treatment (FDA labels of both drugs). Serotonergic drugs, escitalopram included, are not taken for 72 hours after the last methylene blue dose (FDA methylene blue label).

Mechanism

Moxifloxacin is named outright in both SSRI labels. Its own SmPC forbids concomitant use with other QT-prolonging drugs and quotes the measured QTc increase of about 6 ms. The escitalopram SmPC contraindicates any QT-prolonging drug alongside it: the ban is written broadly, and the classes in brackets are examples.

Symptoms

QTc prolongation on ECG, palpitations, dizziness, syncope. The end point is polymorphic ventricular tachycardia of the torsade type progressing to ventricular fibrillation. The risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, decompensated heart failure and in women.

Management

The pair sits in the escitalopram SmPC contraindications, so the question is which drug stays, not how far to cut the dose. Moxifloxacin is the most cardiac of the fluoroquinolones, and respiratory infections have replacements outside that group. This pair is resolved on the antibiotic side.

Mechanism

Escitalopram is an SSRI. Combined with phenelzine causes serotonin syndrome. FDA Nardil Section 4.

Symptoms

Hyperthermia, myoclonus, tachycardia.

Management

Combination contraindicated. 2-week washout.

Mechanism

Both drugs prolong the QT interval: escitalopram in a dose-dependent way (escitalopram label), pimozide up to ventricular arrhythmias at therapeutic doses (pimozide label). No study of this exact pair exists. The labels rely on data with racemic citalopram: a single 2 mg dose of pimozide given with citalopram 40 mg once daily increased QTc by a mean of about 10 ms (pimozide label, FDA). The US escitalopram label adds that racemic citalopram increases plasma concentrations of pimozide, a drug with a narrow therapeutic index. There is also a kinetic side: escitalopram inhibits CYP2D6 (escitalopram label), this enzyme partly metabolises pimozide, and the Spanish pimozide label contraindicates CYP2D6 inhibitors (pimozide label).

Symptoms

QT prolongation causes no symptoms and shows only on the ECG. The danger is ventricular arrhythmia, above all torsade de pointes. The escitalopram label reports such cases mainly in women and in patients with hypokalaemia, a pre-existing long QT interval or other heart disease. The pimozide label also reports ventricular tachycardia, ventricular fibrillation and sudden death. Arrhythmia presents as dizziness, palpitations or syncope.

Management

The combination is contraindicated. The Spanish pimozide label names escitalopram in its contraindications (pimozide label, AEMPS). The Spanish escitalopram label bans concomitant use with drugs that prolong the QT interval and names pimozide among the examples (escitalopram label). The US labels of both drugs repeat the ban (escitalopram and pimozide labels, FDA). Do not give escitalopram to a patient on pimozide; if a patient already takes both, stop one of the drugs. The pimozide ban extends to sertraline, paroxetine and citalopram (pimozide label) and to any drug that prolongs the QT interval (pimozide and escitalopram labels). Choose the replacement outside those lists. For any pimozide treatment, take an ECG before the start and repeat it during treatment, correct potassium and magnesium before the start, and stop pimozide if QT or QTc exceeds 500 ms (pimozide label). If signs of arrhythmia appear on escitalopram, stop it and take an ECG (escitalopram label).

Mechanism

Quetiapine is an atypical antipsychotic, and antipsychotics appear among the QT examples in both SSRI labels. Post-marketing reports describe QT prolongation at therapeutic doses, and the quetiapine SmPC calls for caution with any QT-prolonging drug. The escitalopram SmPC contraindicates any QT-prolonging drug alongside it: the ban is written broadly, and the classes in brackets are examples.

Symptoms

QTc prolongation on ECG, palpitations, dizziness, syncope. The end point is polymorphic ventricular tachycardia of the torsade type progressing to ventricular fibrillation. The risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, decompensated heart failure and in women.

Management

The pair sits in the escitalopram SmPC contraindications, so the question is which drug stays, not how far to cut the dose. Quetiapine is often added to an antidepressant in resistant depression, which is exactly why this pair deserves attention up front: the SSRI label files antipsychotics under contraindicated combinations. If the regimen is assembled anyway, an ECG with QTc is taken before the start and two weeks in, with potassium and magnesium kept normal.

Mechanism

Tacrolimus can prolong QT and cause torsade, in the words of its SmPC, which also calls for caution in patients already on QT-prolonging drugs. The escitalopram SmPC contraindicates any QT-prolonging drug alongside it: the ban is written broadly, and the classes in brackets are examples.

Symptoms

QTc prolongation on ECG, palpitations, dizziness, syncope. The end point is polymorphic ventricular tachycardia of the torsade type progressing to ventricular fibrillation. The risk is higher with hypokalaemia, hypomagnesaemia, bradycardia, decompensated heart failure and in women.

Management

The pair sits in the escitalopram SmPC contraindications, so the question is which drug stays, not how far to cut the dose. Tacrolimus is not withdrawn after transplantation, so the antidepressant is chosen around it rather than the other way round. With QT-prolonging co-medication the tacrolimus label explicitly requires ECG monitoring and blood level control.

Mechanism

Escitalopram (SSRI) depletes the platelet serotonin pool, impairing primary haemostasis. Aspirin irreversibly blocks platelet cyclooxygenase. Combined, GI bleeding risk roughly doubles.

Symptoms

Gum bleeding, epistaxis, bruising without trauma, black tarry stools, blood in urine. Severe cases include gastrointestinal or intracranial haemorrhage.

Management

The combination is acceptable at low aspirin doses (75–100 mg as cardioprotection). Mandatory PPI cover with pantoprazole. Alternative antidepressants with minimal platelet effect: mirtazapine or agomelatine.

Mechanism

Escitalopram (SSRI) depletes the platelet serotonin pool, impairing primary haemostasis. Apixaban inhibits factor Xa. Combined, GI bleeding risk rises 1.5- to 2-fold.

Symptoms

Gum bleeding, epistaxis, bruising without trauma, black tarry stools, blood in urine. Severe cases include gastrointestinal or intracranial haemorrhage.

Management

The combination is acceptable. PPI cover with pantoprazole is mandatory. Alternative antidepressants with minimal platelet effect: mirtazapine or agomelatine.

Mechanism

Escitalopram is a citalopram enantiomer with the same effects. Additive seizure threshold reduction (bupropion + escitalopram). High-dose escitalopram prolongs QT.

Symptoms

Seizures (especially with prior epilepsy or eating disorders), QT prolongation on ECG, dizziness.

Management

The combination is used to augment antidepressant response, but bupropion is contraindicated in patients with a seizure history per the label. Start bupropion at a low dose and titrate gradually. Start escitalopram at the low end of its dose range when bupropion is already on board, and if bupropion is added to an established escitalopram regimen, consider reducing the escitalopram dose. When bupropion is prescribed for smoking cessation in a patient taking an antidepressant, the label advises a maximum of 150 mg a day. Watch for agitation, tremor, myoclonus and fever (serotonin syndrome) during the first weeks and after dose increases.

Mechanism

SSRI + SNRI – serotonergic load rises, serotonin syndrome risk. The combination has no therapeutic rationale.

Symptoms

Serotonin syndrome: agitation, confusion, tremor, myoclonus, hyperreflexia. Autonomic features: sweating, tachycardia, hypertension, fever. First signs appear within hours of co-administration.

Management

The combination is not prescribed. When switching antidepressants, allow a 1-week washout. For augmentation, use mirtazapine or agomelatine.

Mechanism

Fluoxetine belongs to the same class, and its SmPC warns about serotonergic reactions when it is combined with other serotonergic agents. Two SSRIs bring no added benefit, while the serotonergic effect stacks.

Symptoms

Serotonin syndrome: agitation, confusion, tremor, myoclonus, hyperreflexia, sweating, diarrhoea, tachycardia, and in severe cases hyperthermia and rigidity. Symptoms usually appear within a day of adding the second drug or raising the dose. In patients with cardiac risk factors QTc is tracked separately.

Management

Stopping fluoxetine does not end the interaction at once: its SmPC gives a half-life of 4-6 days, and 4-16 days for the active metabolite norfluoxetine. A switch is measured in weeks, and the same label requires this to be taken into account when changing antidepressant.

Mechanism

Ketoconazole prolongs the QT interval and strongly inhibits CYP3A4, one of the pathways that metabolise escitalopram. The escitalopram label contraindicates concomitant use with QT-prolonging drugs, and that is the main argument for this pair; the metabolic rise in concentration only adds to it. Topical ketoconazole – shampoo, cream – has minimal systemic absorption and this pair does not apply to it.

Symptoms

Palpitations, dizziness, syncope; on ECG, a prolonged QTc. From the escitalopram side, nausea, insomnia, tremor and sweating as signs of a high concentration.

Management

The combination is avoided. For dermatophyte infection terbinafine or topical treatment serves; for systemic mycosis, a different azole or an echinocandin depending on the fungus. If there is no alternative, an ECG before starting and a few days in, with potassium and magnesium corrected beforehand and the escitalopram dose at the low end.

Mechanism

Mirtazapine acts on serotonergic transmission through a different mechanism, and its SmPC names SSRIs among the drugs that can bring on serotonin syndrome. Reports of QT prolongation and torsade with mirtazapine come mainly from overdose and from patients with other risk factors.

Symptoms

Serotonin syndrome: agitation, confusion, tremor, myoclonus, hyperreflexia, sweating, diarrhoea, tachycardia, and in severe cases hyperthermia and rigidity. Symptoms usually appear within a day of adding the second drug or raising the dose. In patients with cardiac risk factors QTc is tracked separately.

Management

The mirtazapine label does not forbid the combination. It asks for watching serotonergic symptoms in the first days after the start and after every dose increase. An ECG with QTc is for those who already carry cardiac risk factors.

Mechanism

Two separate risks add up in the same pair. First the mucosa: the corticosteroid slows epithelial turnover and escitalopram depletes platelet serotonin, so gastrointestinal bleeding risk rises. Second the rhythm: escitalopram prolongs the QT interval in a dose-dependent way, and a systemic corticosteroid drives potassium loss. The droperidol and amiodarone labels name glucocorticoids alongside potassium-wasting diuretics as drugs that induce electrolyte imbalance and raise torsade de pointes risk. The escitalopram label contraindicates use with QT-prolonging drugs and asks for hypokalaemia and hypomagnesaemia to be corrected before starting.

Symptoms

On the gastrointestinal side: epigastric pain, black stools, coffee-ground vomit, anaemia with no obvious cause. On the cardiac side: palpitations, dizziness, syncope; on ECG, a prolonged QTc. Muscle weakness and cramps flag the low potassium that precedes the arrhythmia.

Management

Potassium and magnesium before the pair starts and during follow-up, with an ECG and QTc if the corticosteroid runs for weeks or other factors are present: older age, heart disease, another QT-prolonging drug. The escitalopram dose over 65 is capped at 10 mg a day per the label. With a corticosteroid beyond two weeks, a history of ulcer or older age, gastroprotection with a proton pump inhibitor is added. Check whether the corticosteroid is still indicated: the shortest route is stopping what is no longer needed.

Mechanism

Sertraline belongs to the same class. Its SmPC states outright that the risk of serotonin syndrome and neuroleptic malignant syndrome rises with concomitant serotonergic drugs, other antidepressants included. Post-marketing reports also describe QTc prolongation with torsade, mostly in patients with other risk factors.

Symptoms

Serotonin syndrome: agitation, confusion, tremor, myoclonus, hyperreflexia, sweating, diarrhoea, tachycardia, and in severe cases hyperthermia and rigidity. Symptoms usually appear within a day of adding the second drug or raising the dose. In patients with cardiac risk factors QTc is tracked separately.

Management

Two SSRIs together add no effect while their risks stack. Most often the pair is the trace of an unfinished switch, and one drug stays in the regimen.

Mechanism

Venlafaxine blocks serotonin and noradrenaline reuptake, so the serotonergic effect stacks with an SSRI. Its SmPC bans only irreversible MAOIs, describing other serotonergic combinations as ones to be watched. QTc prolongation and torsade were recorded post-marketing, mostly in overdose.

Symptoms

Serotonin syndrome: agitation, confusion, tremor, myoclonus, hyperreflexia, sweating, diarrhoea, tachycardia, and in severe cases hyperthermia and rigidity. Symptoms usually appear within a day of adding the second drug or raising the dose. In patients with cardiac risk factors QTc is tracked separately.

Management

The pair usually appears while switching from one antidepressant to another, and the overlap is kept short. Agitation, tremor, sweating and hyperthermia in the first days after a dose change are the warning signs.

Mechanism

Additive sedation. No direct pharmacokinetic interaction – escitalopram does not significantly block CYP3A4.

Symptoms

Additional drowsiness, ataxia in the first 1–2 weeks. Older patients: fall risk.

Management

Widely used in anxious-depressive disorders. Alprazolam is given for a short course (4–6 weeks) with gradual taper after escitalopram's effect stabilises. In older patients: minimum alprazolam dose; monitor cognition.

Mechanism

This pair meets at three points. Tramadol inhibits serotonin reuptake, so with escitalopram the risk of serotonin syndrome rises. Both drugs lower the seizure threshold (both SmPCs). The third point is kinetic: most of the analgesia comes from a tramadol metabolite formed via CYP2D6, and escitalopram inhibits this enzyme (escitalopram SmPC). Less active metabolite is formed and more tramadol itself stays in the blood (FDA tramadol label).

Symptoms

Serotonin syndrome: agitation, confusion, tremor, myoclonus, hyperreflexia, sweating, diarrhoea, tachycardia, and in severe cases hyperthermia and rigidity. Seizures can occur on this combination, including without serotonin syndrome. When less active tramadol metabolite is formed, pain relief is weaker than expected.

Management

The combination is allowed but needs monitoring. In a patient with depression, the FDA tramadol label advises considering a non-opioid analgesic first. If tramadol is still needed, keep the daily dose at or below 400 mg, because seizure risk rises above it (tramadol SmPC). Tramadol is contraindicated in epilepsy that is not controlled; in controlled epilepsy it is used only when the circumstances require it, with close observation (both SmPCs). Watch for signs of serotonin syndrome at the start of co-treatment and after each dose increase. If they appear, stop both drugs at once and start symptomatic treatment (escitalopram SmPC). If escitalopram is being started, correct potassium and magnesium first, and in stable heart disease consider an ECG before the first dose. Escitalopram is contraindicated with a prolonged QT interval. If signs of arrhythmia appear, such as palpitations, skipped beats or fainting, stop escitalopram and do an ECG (escitalopram SmPC).