Antihistamines may either be first-generation or second-generation medications. First-generation antihistamines may increase the risk of an acute glaucoma attack, but what about second-generation antihistamines such as Claritin (loratadine)?*

The Effect of Older Antihistamines on People with Glaucoma

Older, first-generation antihistamines are known for having a stronger anticholinergic effect, meaning they block the responses of the sphincter muscle of the iris and the ciliary muscle of the lens to cholinergic stimulation. They, therefore, produce mydriasis (dilation of the pupil). Dilating the pupil in a susceptible eye increases the danger of developing a pupillary block.

First-generation antihistamines that should be avoided include:

• Benadryl (Generic: Diphenhydramine)
• Chlor-Trimeton (Generic: Chlorpheniramine)
• Dramamine (Generic: Dimenhydrinate)
• Doxylamine
• Tavist (Generic: Clemastine)
• Brompheniramine

Aside from an increase in the risk of an acute glaucoma attack, people who take first-generation antihistamines may also notice dry eyes and blurry vision. Elderly people are even more vulnerable to these adverse effects.

Choosing Second-Generation Antihistamines

To reduce the risk of negative side effects from anticholinergics, second-generation antihistamines are preferred, such as:

• Claritin (Generic: Loratadine)
• Zyrtec (Generic: Cetirizine)
• Allegra (Generic: Fexofenadine)

Claritin and Allegra may be considered to be the safest options. Always check with your doctor about over-the-counter medications before you start them to make sure they do not adversely interact with your condition and any medications you’re already taking.

*Staiger, B. (2019, October 28). Is Claritin Safe If You Have Glaucoma? Walrus. https://walrus.com/questions/is-claritin-safe-if-you-have-glaucoma