Are Antihistamines Dangerous?

I’ve been battling allergies – to pollens, mostly – for many years. However, I’m getting nervous about taking antihistamines. They seem to work less well than they once did, and I’ve heard that they can increase the risk of dementia. Can you suggest alternatives?

– May 12, 2017

Antihistamines can be problematic. They’re among the drugs discussed in my new book Mind Over Meds: Know when Drugs are Necessary, When Alternatives are Better—and When to Let Your Body Heal on Its Own. Because so many people use antihistamines and because of the risks they can present, I asked Randy Horwitz, M.D., Ph.D., an internist/allergist/immunologist who is the medical director of the University of Arizona Center for Integrative Medicine, to help me write the chapter addressing these drugs.

As you probably know, sedation is one of the disturbing side effects of the oldest – and still commonly used – antihistamines, such as diphenhydramine (Benadryl), chlorpheniramine (Chlor-Trimeton), and clemastine (Tavist). The drowsiness these drugs cause can be dangerous, which is why the packages carry warnings about driving or operating heavy machinery when taking them. More disturbing, Dr. Horwitz writes, is the finding that taking these antihistamines for the equivalent of three years or more increased the risk of dementia by 54 percent (in a study of more than 3,000 men and women over the age of 65). Because the study was observational, it didn’t prove that the antihistamines caused dementia but did show a worrisome association. (People who take over-the-counter sleeping medications (Unisom, ZzzQuil, SleepGels) may not be aware that they contain these antihistamines.)

Dr. Horwitz also warns that taking antihistamines can cause or worsen depression and interfere with thinking and concentration. Some evidence also links them with an increased risk of glioma, the most common type of malignant brain tumor.

Fortunately, there are effective natural alternatives for allergy treatment. Here are some of the ones I recommend:

  • High-efficiency particulate air (HEPA) filters. These remove particles of pet dander and pollen from the air by forcing it through screens with microscopic pores.
  • Frequent nasal irrigation with a warm saline solution
  • Stinging nettle leaves (Urtica dioica): For the runny nose and watery, itchy eyes of allergic rhinitis. Available in freeze-dried form in capsules. The usual dose is 1 to 2 capsules every 2 to 4 hours as needed.
  • Butterbur (Petasites hybridus): For treatment of allergies, asthma and migraines. Compared to the drug Zyrtec for hay fever, 4 to 5 doses of butterbur daily have been shown to be as effective, less sedating and have fewer side effects.
  • Mind-body interventions, including hypnosis, can reduce allergic responsiveness in many people.
  • An anti-inflammatory diet: This can reduce allergic reactivity in general. Simply adding omega-3 fats to the diet in the form of fatty fish or fish oil supplements can accomplish this in many people and provide significant benefits.

Andrew Weil, M.D.


Read an excerpt from Mind Over Meds – “Too Many Meds: The Problem And The Solution

Related Weil Products

Dr. Weil on Healthy Aging for a Healthy Mind

Want to help protect your memory? You can reduce your risk of developing diseases influenced by inflammation, including Alzheimer’s, simply by following an anti-inflammatory diet like the one featured on the Dr. Weil on Healthy Aging online guide. Start your free trial today and get 14 days free!
Get Started

Share Dr. Weil's expertise with your friends & family