Famotidine and Intraocular Pressure
There is no evidence that famotidine (an H2 blocker) affects intraocular pressure or pre-glaucoma risk. The provided evidence exclusively addresses alcohol, acetazolamide, dexmedetomidine, prostaglandins, and general glaucoma risk factors—none of which relate to H2 receptor antagonists like famotidine.
Evidence Gap
The systematic reviews and guidelines on IOP and glaucoma risk factors 1 do not identify H2 blockers as medications that influence intraocular pressure 1
Medications known to affect IOP include carbonic anhydrase inhibitors (acetazolamide), prostaglandin analogs, and alpha-2 agonists (dexmedetomidine) 2, 3, 4, 5, but H2 antagonists are not among these drug classes
The American Academy of Ophthalmology guidelines on primary open-angle glaucoma identify specific systemic risk factors including hypertension, hypothyroidism, migraine, and vasospasm 1, but do not mention H2 blockers or famotidine as relevant factors
Clinical Implications
Famotidine can be safely prescribed without concern for IOP elevation or glaucoma risk based on the absence of any documented association in glaucoma literature
Patients with pre-glaucoma or established glaucoma taking famotidine do not require additional IOP monitoring beyond standard glaucoma care protocols 1
Focus IOP management on established modifiable risk factors: baseline IOP level, age, family history, central corneal thickness, and optic nerve susceptibility 1
Important Caveats
While diuretics like furosemide, hydrochlorothiazide, and spironolactone are not indicated for glaucoma treatment 2, this does not extend to H2 blockers, which have an entirely different mechanism of action
Systemic medications that DO affect IOP include those causing pupillary dilation (anticholinergics in angle-closure risk) or those with direct effects on aqueous humor dynamics (carbonic anhydrase inhibitors) 2—famotidine has neither mechanism