Antihistamines are contraindicated for people with urinary tract obstruction, prostate enlargement, glaucoma, stomach ulcers, liver disease, intestinal obstruction, kidney disease, or a known allergy to the specific antihistamine.
Risks and Side Effects
Common side effects of antihistamines are sedation; dry mouth, nose, and eyes; excitation in children; and thickening of respiratory secretions. More severe side effects, when the medicine is used for a long period of time, include glaucoma, prostate enlargement, and stomach ulcers.
The main selling feature of combination medicines is that one pill (or liquid dose) will resolve many of your symptoms. These include “allergy and cold relief ” and “sinus pain and headache” remedies. They are available over the counter as well as in prescription dosages. However, I recommend staying away from combinations unless you have discussed them with your doctor. Combination medicines often contain elements that you might not need, and you will bear the negative side effects of
that element even though it is not doing anything for you. For example, a decongestant with a built-in antihistamine will make you more tired than you would feel by taking the decongestant alone. Furthermore, you risk experiencing the side effects of the antihistamine you do not need.
First-Generation Oral Antihistamines
Be sure to read the box your medicine comes in to determine its primary ingredients. Many products contain the following drugs in some combination with other agents.
Brompheniramine, available as a combination product (Dimetapp) Chlorpheniramine (Chlor-Trimeton)
Cyproheptadine (Periactin, prescription only)
Dexbrompheniramine, available as a combination product (Drixoral) Diphenhydramine (Benadryl)
Promethazine (Phenergan, prescription only)
Second-Generation Oral Antihistamines
Products labeled “D” also contain the decongestant pseudoephedrine.
Acrivastine (Semprex-D, prescription only)
Cetirizine (Zyrtec, Zyrtec-D, prescription only)
Desloratadine (Clarinex RediTabs, prescription only)
Fexofenadine (Allegra, Allegra-D, prescription only)
Loratadine (Claritin, Dimetapp ND, Alavert, Claritin RediTabs, Claritin-D)
Topical Nasal Antihistamines
Topical nasal antihistamines work in the same fashion as oral antihistamines and have minimal side effects. This type of nasal spray does not cause a rebound effect. It is usually prescribed for patients with sinus and/or nasal problems caused by allergy. One type is azelastine (Astelin), available by prescription only.
Topical Ophthalmic Antihistamines
Topical ophthalmic antihistamines are used when the eyes are severely affected by an allergic reaction. These eye drops will reduce swelling, itching, and tearing in and around the eye.
Antazoline/naphazoline, an antihistamine/decongestant combination (Vasocon-A)
Pheniramine/naphazoline, an antihistamine/decongestant combination (Naphcon-A, Visine-A)