Different medications can treat allergies, including steroids and allergy shots, but the first thing to try is usually an antihistamine.
How antihistamines treat allergies
When your body comes in contact with the trigger for your allergy – pollen, ragweed, animal dander, or dust mites, for example – it produces chemicals called histamines. They cause the tissues in your nose to swell (making them stuffy), your nose and eyes runny, and your eyes, nose and sometimes your mouth itch. Sometimes you may also have an itchy rash called hives.
Antihistamines reduce or block histamines, so they stop allergy symptoms.
These medications work well for relieving symptoms of different types of allergies, including seasonal (hay fever), indoor, and food allergies. But they can’t alleviate all the symptoms.
To treat nasal congestion, your doctor may recommend a decongestant. Some drugs combine an antihistamine and a decongestant.
What types of antihistamines are available?
They come in different forms, including tablets, capsules, liquids, nasal sprays, and eye drops. Some are only available on prescription. Others can be purchased over the counter (OTC) at your local pharmacy.
Prescription antihistamines include:
Over-the-counter antihistamines include:
Eye drops treat the symptoms of eye allergies, including itching and watery eyes. Some medications combine an antihistamine and a decongestant to relieve congestion.
Side effects of antihistamines
The older ones tend to have more side effects, especially drowsiness.
Newer antihistamines have fewer side effects, so they may be a better choice for some people.
Some of the main side effects of antihistamines include:
If you are taking an antihistamine that causes drowsiness, take it before bed. Do not take it during the day before driving or using machines.
Read the label before taking any allergy medication. Antihistamines can interact with other medicines that you are taking.
Talk to your doctor first if you have an enlarged prostate, heart disease, high blood pressure, thyroid problems, kidney or liver disease, bladder obstruction, or glaucoma. Also consult your doctor if you are pregnant or breastfeeding.