Major
Doxycycline × isotretinoin
Tetracyclines×Systemic retinoid (vitamin A derivative)
Mechanism
Both drugs cause benign intracranial hypertension (pseudotumor cerebri). Additive risk with classic presentation: headache, diplopia, visual disturbance, optic disc oedema.
Symptoms
Persistent pressing headache (not relieved by analgesics), diplopia, transient visual disturbances, tinnitus. Examination: optic disc oedema, blind spot enlargement. Symptoms appear several weeks into combination.
Management
The combination is not prescribed. Alternative antibiotic for acne on isotretinoin: azithromycin (short course) or topical retinoids. If headache with diplopia appears, stop both drugs immediately and refer to ophthalmology.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.