Between 15% and 25% of the population around the world suffers from periodic allergic rhinitis. It can be occasionally annoying or severe enough to affect the quality of life. Antihistamines are the primary medication used to treat this and other forms of allergy.1
The older types of these medications, the first-generation antihistamines, are sedating. For that reason, they tend to be used more often as sleeping pills. Indeed, some 12% of those over age 65 take such medications for insomnia. This is concerning since over-the-counter sleep medications with the antihistamines diphenhydramine (Benadryl) and doxylamine (Unisom) are on the Beers List – medications to be avoided in those over age 65 because they can cause difficulty with thinking, problems with coordination, can worsen kidney or liver insufficiency, and lead to dizziness and falls. They are a common source of drug interactions including with some antidepressants and cardiac medications.2
Antihistamines are one of the most commonly prescribed drugs for children. Per a Cochrane Review (medical studies that are well-known for their scientific analysis and for thoroughness), the effectiveness of antihistamines for treating nonspecific cough in children is not certain. Also, children are more susceptible to antihistamine adverse effects, including sedation as well as paradoxical agitation and excitability.3 Topical antihistamines should be avoided in children
Some people also take antihistamines for their cold symptoms. While the older, first generation antihistamines may dry secretions, they can thicken the mucus excessively so that it is harder to cough them up.3
Antihistamines are effective in the treatment of allergic rhinitis and chronic urticaria. For chronic allergy symptoms, regular use of an antihistamine is probably more effective than taking them only as needed. Allergic conjunctivitis is probably better treated with antihistamine eye medications. Antihistamine effects vary from person to person so if one type doesn’t help, another may. 4, 5
First generation antihistamines are not recommended because they can cause sedation as well as difficulty thinking. These medications should be avoided not only in those over 65 years of age, but also those with glaucoma, constipation, dementia, or benign prostate enlargement. Second generation antihistamines are much less likely to cause sleepiness but it can have this effect in some, especially in higher doses.5
Because many types of antihistamines are sold without a prescription, it is essential to discuss any use of them with your pharmacist so that they can determine if there are any interactions with your prescriptions. And remember, it is far superior to try to determine what is causing an allergic reaction and make every effort to eliminate exposure to such.
This article is not intended to replace your health care provider. The intent is to make important information about medications available.
1D. Passali, et al, “The International Study of the Allergic Rhinitis Survey: outcomes from 4 geographic regions,” Asia Pacific Allergy, January, 2018; 8 (1): e7.
2O. Abraham, et al, “Over-the-Counter medications containing diphenhydramine and doxylamine used by older adults to improve sleep.” International Journal of Clinical Pharmacy 297; 39(4) 808-817.
3J. Van Schoor, Antihistamines: A brief review, Professional Nursing Today, 2012: 16(5).
4Dr. Koop’s Self-Care Advisor. Time Life Medical Books, 1996.
5The Merck Manual, 19th edition. Whitehouse, New Jersey: Merck, Sharp and Dohme, 2011.