Antihistamines and Your Asthma

In This Article

While antihistamines are not asthma medications per se, that does not mean your asthma might not benefit from them.


If you have a lot of allergy symptoms, your doctor may use antihistamines to help provide relief, as well as get control of your asthma. Histamine is a normal part of your body's defense mechanisms, but when histamine is released in response to an allergen, you may develop allergy symptoms. Antihistamines are available as prescriptions and over-the-counter (OTC) medications.

How They Work

As you might expect from its name, antihistamines act against histamine. In asthma and allergies, histamine is released as an overreaction by your immune system to an allergen.

Histamine is released by mast cells and basophils. It can cause symptoms all over your body, depending on where the histamine gets released:

  • Nose: runny, watery nose
  • Eyes: itchy, tearful (but you're not sad!)
  • Throat: irritated, sore, scratchy
  • Lung: wheezing, chest tightness, shortness of breath, and cough

An antihistamine works by preventing mast cells and basophils from attaching to the parts of your body where histamine can be released and cause symptoms.


When you experience a runny nose, sneezing, and itchy watery eyes, you may want to try an OTC antihistamine medication first. Some popular OTC antihistamine medications include:

  • Zyrtec
  • Claritin
  • Benadryl

If you are not able to get your allergy symptoms under control with an OTC antihistamine, your doctor may prescribe one of the following prescription antihistamines:

  • Allegra
  • Clarinex
  • Xyxal

Both the older and newer antihistamines are also available as part of a combination product that contains pseudoephedrine.

Common Side Effects

While most people do not experience side effects when taking an antihistamine, you need to be aware of the potential. First-generation antihistamines like brompheniramine (Dimetapp) and diphenhydramine (Benadryl) can make you sleepy. This is because these particular drugs also go to the part of the brain responsible for nausea and vomiting (they can also be used to treat or prevent motion sickness).

Second-generation antihistamines are less likely to cause this side effect but are no more effective in controlling symptoms and cost more money. The higher the dose of medication you take, the more likely you will experience side effects.

If you are older than 60, you are at greater risk of becoming drowsy with an antihistamine, and may also have an increased risk of falling.

Additional common side effects include:

  • Dizzy
  • Dry mouth
  • Hoarseness
  • Nausea

Most of these side effects will resolve over time. However, if you experience any of the following side effects consider talking with your doctor:

  • Changes in vision
  • Extreme nervousness
  • Racing heartbeat
  • Stomach pain
  • Stop or have difficulty urinating
  • Yellowing of skin
  • Weakness

Additionally, you need to be careful and watch out for side effects if you combine antihistamines with:

  • Muscle relaxants
  • Pain medications
  • Sedatives like alcohol
  • Sleeping pills

Because antihistamines can also react with some antibiotic and antifungal drugs, it is extremely important for every doctor that treats you knows your medications. Make sure you bring the pill bottles with you or at least an up to date list. If you get a new prescription make sure to ask your pharmacist to check to make sure there will be no dangerous interactions.

Talk with your doctor before taking antihistamines if you have any of the following conditions, as they can make some conditions worse:

  • Benign prostatic hypertrophy or an enlarged prostate
  • Breathing conditions such as asthma or COPD
  • Heart problems
  • Hypertension or high blood pressure
  • Thyroid problems

Alternative Options

If antihistamines don't get your allergy symptoms under control and your asthma is still bothersome, your doctor may consider adding a nasal steroid, leukotriene blocker, Xolair, or immunotherapy.

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Article Sources
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  1. American Chemical Society. Histamine. Published 2018.

  2. Scaglione F. Safety profile of bilastine: 2nd generation H1-antihistamines. Eur Rev Med Pharmacol Sci. 2012;16:1999–2005.

  3. Simons FE, Simons KJ. Histamine and H1-antihistamines: celebrating a century of progress. J Allergy Clin Immunol. 2011;128(6):1139-1150.e4. doi:10.1016/j.jaci.2011.09.005

  4. Alvarez CA, Mortensen EM, Makris UE, et al. Association of skeletal muscle relaxers and antihistamines on mortality, hospitalizations, and emergency department visits in elderly patients: a nationwide retrospective cohort study. BMC Geriatr. 2015;15:2. doi:10.1186/1471-2318-15-2

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