Antihistamines for allergic rhinitis
Viewed 465 times
-
Antihistamines are available as tablets, capsules, nasal sprays, and liquids. They may be used alone or combined with decongestants in the treatment of allergic rhinitis. Examples of antihistamines now on the market include:
Older (first-generation) antihistamines
Brand Name Chemical Name
Dimetane brompheniramine maleate
Clarinex desloratadine
Claritin, Alavert loratadine
Most first-generation antihistamines are available without a prescription.
Newer prescription (second-generation) antihistamines
Brand Name Chemical Name
Dimetane brompheniramine maleate
Clarinex desloratadine
Claritin, Alavert loratadine
Cetirizine hydrochloride (Zyrtec) and desloratadine (Clarinex) are available in pill and liquid form. Desloratadine is also available as "Reditabs," small tablets that dissolve on the tongue. Fexofenadine (Allegra) is available in pill form. Azelastine (Astelin) is available as a nasal spray only.
Newer nonprescription (second-generation) antihistamines
Brand Name Chemical Name
Dimetane brompheniramine maleate
Clarinex desloratadine
Claritin, Alavert loratadine
Loratadine is available in pill, liquid, and Reditab form.
(back to top)
How It Works
Many symptoms of allergic rhinitis, such as sneezing, itching, and runny nose, occur when a chemical called histamine is released as part of the allergic reaction to an irritant (allergen). Antihistamine medications block the reaction of histamine with its receptors on cells and reduce the severity of some allergy symptoms.
(back to top)
Why It Is Used
Antihistamines are used to stop or reduce sneezing, runny nose, and watery and itchy eyes caused by an allergic reaction.
(back to top)
How Well It Works
All of these antihistamines work equally well to relieve sneezing, itching, and runny nose.
Antihistamines begin to provide relief in 30 minutes to 2 hours.
Antihistamines dry up the runny nose caused by allergies, but they do not always clear up stuffiness. Allergy formulations of nonprescription oral antihistamines (taken by mouth as a pill) are often combined with a nonprescription decongestant to help nasal congestion; examples include Actifed, Allerest, Bromfed, Dimetapp, and Drixoral.
(back to top)
Side Effects
The older (first-generation) antihistamines can make you sleepy or make it harder for you to concentrate. They may also affect your coordination, even when they do not make you drowsy. These medications should be used carefully if you need to drive or operate dangerous or heavy machinery. After an antihistamine has been taken several times, most people are able to predict whether and when they will become sleepy. For some people the side effects become less severe after taking the medication for a few days.
Other side effects may include:
Dry mouth.
A bitter taste in the mouth.
Nausea and vomiting.
Restlessness or irritability, especially in children.
Inability to urinate (urinary retention).
Blurred vision.
Rapid heartbeat (tachycardia), from decongestants in formulations that combine antihistamines and decongestants.
Some antihistamines should be used carefully if you have certain conditions. If you have any of the following health conditions, talk with your health professional before using the medication:
Glaucoma or other conditions that cause increased pressure inside the eye
Urinary problems due to prostate enlargement
Thyroid conditions
Asthma
Liver, kidney, heart, or lung disease
Newer, second-generation antihistamines have fewer side effects. Many of the new antihistamines cause less drowsiness than older antihistamine medications or cause no drowsiness at all. Azelastine may cause drowsiness in some people, although this is uncommon.
See Drug Reference for a full list of side effects. (Drug Reference is not available in all systems.)
(back to top)
What To Think About
The newer (second-generation) antihistamines are much more expensive than the older (first-generation) antihistamines.
Some of the newer antihistamines need be taken only once a day.
In general, antihistamines don't relieve nasal congestion well, and additional medications, such as decongestants, may be needed.
Fexofenadine may cause menstrual cramps, nausea, and fatigue.
Older adults and pregnant or breast-feeding women should talk to their health professionals before using antihistamines.
Azelastine has been approved for use in children older than age 12.
Desloratadine (Clarinex ) is approved for seasonal allergic rhinitis in children age 2 years and older and for perennial allergic rhinitis in children age 6 months and older. The liquid form of desloratadine may not yet be available in your area.
Children cannot use all antihistamines. Talk with your health professional before giving them to your child.
