Severe allergic reactions
Life-threatening systemic allergic reactions. First-line treatment for anaphylaxis is epinephrine. Glucocorticoids are given as adjuncts to prevent biphasic reactions and suppress the late-phase allergic response.
ICD-10 T78.25 drugs
Also known as: Anaphylaxis, Severe drug allergy, Angioedema
Drugs used for this condition
- BBetamethasoneAdd-on therapy · Glucocorticoid for systemic useThe AEMPS Betametasona Sonphar label names severe hypersensitivity reactions and anaphylaxis among its indications, while Celestone Cronodose allows intramuscular injection in allergic conditions when oral or local treatment does not fit or is not enough. The drug's place here is supporting. The 2021 EAACI anaphylaxis guideline puts intramuscular adrenaline first and treats corticosteroids and antihistamines as second line: they do not replace adrenaline and do not remove the need for observation because of a possible biphasic reaction. A systemic corticosteroid meanwhile lowers potassium and raises glucose, and together with an NSAID it raises ulcer and bleeding risk, both of which show up in patients with diabetes or heart failure.
- BDexchlorpheniramineAdd-on therapy · First-generation sedating antihistamineIn acute allergic reactions and anaphylaxis, H1 antihistamines are adjuncts to intramuscular adrenaline (first-line) and oxygen. Parenteral dexchlorpheniramine 5 mg IV or IM relieves itching and urticaria but does not address hypotension or bronchospasm. WAO 2020 emphasizes: antihistamines in anaphylaxis do not replace adrenaline and must not delay it.
- BHydrocortisoneAdd-on therapy · Short-acting systemic glucocorticoid, identical to endogenous cortisolThe only first-line treatment for anaphylaxis is intramuscular adrenaline; hydrocortisone never replaces it. Corticosteroids are used as an adjunct to adrenaline, mainly when bronchospasm accompanies the reaction. They do not reliably prevent biphasic reactions (US Practice Parameter 2020, Cochrane 2012). The Resuscitation Council UK (2021) and EAACI (2021) no longer recommend corticosteroids for routine emergency treatment of anaphylaxis; WAO 2020 and the AEMPS label keep them as a second-line adjunct.
- BPrednisoloneAdd-on therapy · GlucocorticoidsIn anaphylaxis, epinephrine is first-line; prednisolone is an adjunct, and the evidence for that role is weak (a 2013 Cochrane review found no eligible RCTs). Prednisolone does not reliably prevent biphasic reactions: the 2020 anaphylaxis practice parameter (JACI) states that glucocorticoids are not a reliable intervention for this. In severe drug reactions (Stevens-Johnson syndrome, serum sickness) systemic steroids are sometimes used at high doses, but the approach remains debated.
- CChloropyramineAdd-on therapy · First-generation H1 antihistamine, ethylenediamine derivativeChloropyramine is a first-generation antihistamine, registered in Russia in an injectable form among others. The injection is used in acute allergic reactions when the person cannot swallow a tablet. An important correction: in anaphylaxis an antihistamine neither replaces nor delays adrenaline. Intramuscular adrenaline into the anterolateral thigh is the only agent that changes outcome; an antihistamine relieves skin manifestations, itch and urticaria only, and works more slowly. Delaying adrenaline for the sake of an antihistamine injection is a known error with severe consequences. In Spain AEMPS has not registered chloropyramine, and the data here come from the Russian state register.
How to read tiers A–F
Evidence tiers belong to the drug-indication pair, not to the drug as a whole: the same substance can be A for one condition and F for another.
- AStrong evidence – first or second line in international guidelines
- BRecommended in selected cases
- CStudy data contradict each other
- DBenefit not proven, no documented harm
- FDocumented harm, or risk without benefit