Antihistamines and Asthma

Introduction to asthma

Asthma most commonly comes in two forms; one of these is non-atopic asthma, or non-allergenic asthma, in which symptoms are triggered by events not related to allergies.

However, the second type of asthma is atopic, or allergic asthma, and comprises 60% of asthma diagnoses.¹ In these cases, symptoms are triggered by the presence of an allergen, most commonly dust, pollen, pet hair, mould, or other² allergens in the air. 

The immune system registers allergens as ‘threats’ to the body and begins to overreact, releasing histamines. These histamines prompt the airways to become inflamed² and overproduce mucus. In turn, the symptoms most commonly associated with allergic asthma begin to appear, such as coughing, chest tightness, breathing difficulty, and wheezing. 

Role of antihistamines in asthma management 

Antihistamines work by stopping the binding of histamines² to cells and therefore prevent the onset of inflammatory symptoms. They can be especially useful to relieve seasonal allergies and treat asthma’s common comorbidities, such as hay fever and eczema. 

Antihistamines are not typically the first choice of treatment for allergic asthma. More often, your doctor will recommend you use antihistamines to supplement other forms of asthma treatment,² such as rescue inhalers or daily inhalers.

Furthermore, the best way to mitigate allergic asthma symptoms is to avoid triggers. This means dusting often, sweeping up pet hair, washing your sheets, and sticking to your asthma response plan. 

Do antihistamines worsen asthma?

Some reports suggest antihistamines are contraindicated in asthma meaning that they are not appropriate for treating asthma under certain circumstances. These reports rely on the fact that antihistamines dry up mucus production in the airways, which may cause some people with asthma to feel wheezy or have chest tightness.

However, according to a recent study,³ this is mostly a rare event. In fact, allergic asthmatics with chronic symptoms benefit greatly from antihistamines. Especially when their asthma co-occurs with a runny nose, hives, and other symptoms of an allergic reaction. 

If you are allergic to antihistamines, pregnant, nursing, have end-stage kidney disease you must avoid antihistamines as they can mitigate asthma in these conditions.¹ And consult your doctor before taking any medication.

Do antihistamines open airways?

Antihistamines can prevent the inflammation caused by your body’s extreme immune response to the presence of allergens.⁴ By stopping the process of inflammation before it occurs, symptoms are usually relieved or prevented altogether.

Furthermore, if you experience other forms of allergic reactions like puffy eyes, itchy skin, or hay fever, you may find that antihistamines can relieve these symptoms as well.⁵ However, if you’re experiencing extreme airway hyperresponsiveness, or an asthma attack, taking an antihistamine is likely not going to subdue symptoms quickly enough.⁶

Therefore, keeping your rescue inhaler nearby or getting emergency help is much more effective in treating severe asthma symptoms, and speaking to your doctor about the potential of these scenarios is important.

Do antihistamines help with shortness of breath?

Similar to other symptoms of allergic asthma, an antihistamine can stop symptoms before they even begin - including shortness of breath.

However, if you’ve already been exposed to your allergic trigger and breathing is becoming exceedingly difficult, it’s best to seek emergency medical help or utilise your emergency inhaler.

Having an asthma action plan,⁷ where your treatment options are well thought out, and you stay prepared, is the best way to avoid these events and make the most effective use of an antihistamine. 

Do antihistamines help with chest congestion?

One of the methods by which antihistamines prevent asthma symptoms is by limiting the production of airway mucus. Keeping your lungs, throat, and nose free of mucus will relieve swelling, reduce pressure, and improve your ability to breathe.

In the case of severe chest congestion, pairing an antihistamine with a decongestant may treat the multiple factors contributing to this symptom and offer relief.⁸ 

Which antihistamine is best for asthma treatment?

Antihistamines come in many forms,¹ including oral tablets, syrups, nasal sprays, etc. Choosing the brand that’s right for you can be a confusing process of trial and error; however, the best source of help is your pharmacist or your GP. 

Here are a few top sellers and their primary uses: 

• First, Benadryl⁹ is an antihistamine utilised for a wide range of symptoms, commonly hay fever and itchiness. Its most noted side effect is drowsiness. 
• Second, Loratadine¹⁰ improves cold and flu symptoms, such as difficulty breathing and swelling. Its most common side effect is a feeling of agitation (raised heart rate). 
• Third, Cetirizine¹¹ is used similar to Benadryl for topical application, as well as for the improvement of breathing symptoms. Its most common side effect is drowsiness. 

Summary

In conclusion, antihistamines are a great tool for aiding in the management of allergic asthma. Although they may not be the top choice for treating a more severe or chronic condition, they can certainly offer relief during seasonal symptoms. 

If you opt to use an antihistamine to treat your asthma, it is best taken before the onset of severe symptoms. Talk to your GP about how often you experience the symptoms, how severe they are, and if you have any co-occurring symptoms. Your doctor can guide you to the right management plan and even the right antihistamine.