Some people with allergic asthma may find relief from using an antihistamine like Benadryl. But it’s not a recommended asthma treatment.

Asthma is a chronic respiratory condition that causes inflammation of the airways. When your airway passages narrow, it makes it harder to breathe.

People with asthma often experience:

There are two main types of asthma: allergic and non-allergic.

Allergic asthma is caused by exposure to a substance that causes an allergic reaction. Common allergens for allergic asthma include mold, pet dander, pollen, and dust.

Non-allergic asthma is unrelated to allergies and may be caused by stress, illness, weather, exercise, irritants in the air, and some medications.

Some people with allergic asthma may find symptom relief from using an antihistamine like Benadryl if they also experience symptoms of allergic rhinitis. But it’s not a recommended treatment for allergic asthma.

Some people do take over-the-counter antihistamines for allergy symptoms.

Benadryl (diphenhydramine) is a first-generation antihistamine with side effects that include drowsiness and fatigue. It’s short-acting and does not provide long-term relief.

Because the side effects of Benadryl can impair alertness, concentration, and memory, and benefits only last a short time, medical professionals do not typically recommend this medication for allergic asthma. However, they may recommend a newer antihistamine that works longer and has fewer side effects.

Benadryl blocks histamine receptors that are often activated during an allergic reaction. This reverses the effects of histamine on the body. The result is the reduction or elimination of many allergy symptoms.

Research from 2019 found that histamine receptors may play a role in asthma symptoms, and antihistamines may provide relief for some people. Specifically, the study identified a subtype of people with asthma who also have allergic rhinitis. For those who have both conditions, antihistamines may help.

Benadryl relieves symptoms like red, itchy, and watery eyes, as well as runny nose and sneezing. People with allergic asthma may have some of these symptoms, as well as core asthma symptoms like coughing, shortness of breath, chest tightness, and wheezing.

The American Academy of Allergy, Asthma and Immunology lists Benadryl in its antihistamine guide as a treatment for seasonal allergic rhinitis. It recommends a dose of 25–50 milligrams every 4 to 6 hours for adults.

Benadryl may not be right for everyone. Because of its sedating effect, it’s a high risk for some people, such as those over the age of 65.

Some people may need to use it with caution, including people who have other chronic health conditions like asthma, cardiovascular disease, or high blood pressure.

Speak with a doctor before trying Benadryl for allergic asthma. They can help you decide if Benadryl is safe given your overall medical history. A doctor can also help you to develop a comprehensive treatment plan that includes safe and effective short-acting and long-acting medications to manage allergic asthma.

Benadryl works to relieve common allergy symptoms. The medication does not open airway passages in the way first-line asthma treatments do.

Since antihistamines work by countering the allergic reaction, Benadryl may not help with non-allergic asthma unless the same irritations that cause asthma, such as smoke or air pollutants, also cause allergic symptoms.

People with asthma may want to take an antihistamine for other conditions, like a common cold. This is generally safe for people with asthma.

Precautions

Antihistamines are either not recommended or used with caution in the presence of other conditions, such as:

Benadryl and other antihistamines can dry out airway passages. Although this may help relieve symptoms for some people, for others, it may make irritation worse.

People with asthma may have dry mouth from the use of inhalers.

Antihistamines do not work on the core symptoms of asthma, such as chest tightness and shortness of breath. They should not be used in the case of an asthma attack where you are struggling to breathe.

A doctor can recommend the best acute treatment for you to have on hand, such as a rescue inhaler.

Asthma is a treatable condition. It’s possible to manage asthma using a combination of recommended treatments and avoiding your triggers.

Since everyone’s asthma is different, a doctor can help you create a personalized management plan to treat symptoms over the long term.

Asthma medications come in different forms. Inhalers allow you to breathe in the medication so it goes immediately to the lungs. Some asthma medications also come in oral pill or injection form.

Treatments for asthma work by relaxing the muscles around the airways (bronchodilators) and by reducing mucus and swelling (anti-inflammatories).

There are four main types of medications:

  • Quick-relief medications are fast-acting and taken at the first sign of symptoms.
  • Controller medications work over the long term to manage airway changes, such as swelling and mucus.
  • Combination medications are for both quick symptom relief and long-term asthma management.
  • Biologics are injectable medications that target certain types of asthma at the cellular level. They prevent airway swelling.

Antihistamines are not a first-line treatment for asthma. Both allergic and non-allergic asthma are usually managed by a combination of quick relief and controller medications that open the airways and reduce swelling and mucus.

People with allergic asthma may also have symptoms of allergic rhinitis, which Benadryl may be used for. Taking Benadryl for other allergy symptoms may provide relief to some people with allergic asthma, but it will not work on core asthma symptoms.