Second-generation antihistamines (e.g., Claritin, Zyrtec, Allegra OTC) do not carry a prostate warning and would perhaps be a better choice for patients with allergic rhinitis who have BPH.

Is antihistamine bad for prostate?

Antihistamines and decongestants may add to the problem. These drugs can make it harder for the prostate and the bladder to relax, making it even more difficult for urine to flow.

Can Zyrtec enlarge the prostate?

Decongestants, like Pseudoephedrine, Dextroamphetamine, Phenylephrine (Sudafed, Mucinex-D, Allegra-D, Claritin-D, Zyrtec-D, Mucinex DM and their generics) increase the resistance to urine flow through the prostate by causing the smooth muscle in the prostate to squeeze the urethra, which increases urinary problems.