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 into contact with your allergy trigger (pollen, ragweed, pet dander, or dust mites, for example), it makes chemicals called histamines. They cause the tissues in your nose to swell (making them stuffy), run your nose and eyes, and make your eyes, nose, and sometimes mouth itch. Sometimes you may also get an itchy rash on your skin called hives.
Antihistamines reduce or block histamines, so they stop allergy symptoms.
These medications work well to relieve symptoms of different types of allergies, including seasonal (hay fever), indoor, and food allergies. But they cannot relieve all symptoms.
To treat nasal congestion, your doctor may recommend a decongestant. Some medications 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 by prescription. Others can be purchased over-the-counter (OTC) at your local pharmacy.
Prescription antihistamines include:
Over-the-counter antihistamines include:
The eye drops treat the symptoms of eye allergies, including itching and tearing. Some medications combine an antihistamine and a decongestant to relieve congestion.
Side effects of antihistamines
Older ones tend to cause 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 take an antihistamine that causes drowsiness, take it before bedtime. Do not take it during the day before driving or using machines.
Read the label before taking any allergy medicine. Antihistamines can interact with other medications you take.
Tell 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 check with your doctor if you are pregnant or breastfeeding.