Cold and allergy medications that contain antihistamines often come with a warning that people with glaucoma shouldn't use them. However, this really depends on which type of glaucoma you have. People with open-angle glaucoma — the most common type — can safely use antihistamines to treat their allergy symptoms.

But people with closed-angle glaucoma, also called narrow-angle glaucoma or angle-closure glaucoma, should avoid antihistamines or use them with caution. This is because antihistamines may cause enlargement (dilation) of the pupil — which, in rare cases, can trigger an attack of closed-angle glaucoma. Antihistamines generally have no effect on open-angle glaucoma.

If you have glaucoma and have questions or concerns about the use of antihistamines, talk to your doctor.