Advertisement

Do antihistamines have any side effects?

Donna Hill Howes, RN
Family Practitioner

Side effects may include abdominal pain, loss of appetite, nausea, vomiting, diarrhea, and constipation. Other side effects include dry mouth, nose, or throat, vision problems, ringing in the ears, drowsiness, dizziness, insomnia, tremor, nervousness, irritability, and weakness. Some people have trouble emptying the bladder. Men may have erection problems.

Most doctors and guidelines do not recommend using antihistamines to treat sleep problems for many reasons. They are less effective than prescription sleep drugs. They can cause problems with mental and physical function. The sleepiness they cause can carry over into the next day, so that even with more sleep, a person may not feel well-rested. Antihistamines actually cause insomnia in some people. 

This answer was adapted from Sharecare's award-winning AskMD app. Start a consultation now to find out what's causing your symptoms, learn how to manage a condition, or find a doctor.

Some antihistamines (both over-the-counter and prescription) can make you drowsy, slow your reaction time, and impair your judgment. The older "first-generation" antihistamines, which are more likely to cause such effects, include chlorpheniramine (Chlor-Trimeton, others), diphenhydramine (Benadryl), clemastine (Tavist), and brompheniramine (an ingredient in the combination product Dimetapp). The "second-generation" antihistamines have fewer side effects—in particular, drowsiness and nasal dryness—than the older ones. These "non-sedating" medicines include loratadine (Claritin, Alavert, others), available over the counter, and fexofenadine (Allegra), desloratadine (Clarinex), and azelastine (Astelin nasal spray), all available by prescription.

Continue Learning about Nasal Agent

How do decongestants interact with other medications?
Donna Hill Howes, RNDonna Hill Howes, RN
If you are taking linezolid, nasal decongestants can lead to side effects and should be avoided. If...
More Answers
How effective is cromolyn nasal spray?
Donna Hill Howes, RNDonna Hill Howes, RN
Cromolyn can provide relief of nasal itching, sneezing, and runny nose, but is less effective for re...
More Answers
Are tetrahydrozoline eye drops safe for people of all ages?
Stacy Wiegman, PharmDStacy Wiegman, PharmD
Tetrahydrozoline is considered safe. But always check with your health-care provider. Tetrahydrozoli...
More Answers
Does Symbicort cause tooth decay?
Dr. William M. Litaker, DDSDr. William M. Litaker, DDS
The use of Symbicort can result in tooth decay. Symbicort has a side effect of drying the mouth. Per...
More Answers

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.