Antihistamines

Antihistamines may have some beneficial effects in the treatment of asthma. Their benefits, however, are very small compared with more established medications. Therefore, Antihistamines are not recommended specifically for asthma treatment.

Many individuals with asthma may experience symptoms of nasal allergy for which antihistamines are very helpful. Furthermore, antihistamines are considers generally safe for asthmatics.

Antihistamines can be divided into two groups: the older “classic” antihistamines, many of which are available without a prescription, and the newer “second generation” or “non-sedating” antihistamines which have fewer side effects. Both the “classic” and “second generation” antihistamines are available in combination with decongestants.

Classic Antihistamines

Non-Prescription Prescription
Benadryl Atarax
ChlorTrimeton Nolahist
Dimetane Optimine
Efidac PBZ
Tavist Periaction
Teldrin Phenergen
Polyhistine
Temaril
Vistaril

Classic Antihistamine-Decongestants

Non-Prescription Prescription
Actifed Atrohist
Allerest Bromfed
Contac Comhist
Dimetapp Extendryl
Drixoral Kronafed
Isoclor Rynatan
Tavist-D Rutuss
Trinalin

Second Generation Antihistamines

These second generation antihistamines include non-sedating and antihistamine-decongestant combinations (by prescription only).

Allegra
Allegra-D (with decongestant)
Claritin
Claritin-D (with decongestant) 12 &24 hr
Hismanal
Zyrtec
Claritin Repetabs
Claritin Syrup
Semprex —D

Drug Action

Antihistamines block the effects of histamine. They reduce runny nose, sneezing and itching. They are not very effective for nasal stuffiness; these symptoms can be reduced by decongestants.

Side Effects

The most common side effect of classic antihistamines is drowsiness. Other side effects include dry mouth and eyes, stomach upset and decreased urination. The side effects are rarely seen with Second Generation antihistamines. Decongestants may cause irritability, shaking, insomnia, palpitations and stomach upset.

Available Forms

The medications are taken orally, in pill, capsule or liquid forms. Some antihistamines are available for injection. A nasal spray, Astelin is now available.

Indications for Use

These medications are indicated primarily for the treatment of allergic rhinitis to reduce runny nose, sneezing and itching. They are also used to treat hives and other allergic skin conditions.

Contraindications and Precautions

Because many antihistamines cause drowsiness, they should be used cautiously in combination with other sedating medicines and should not be taken with alcohol. Antihistamines may worsen certain forms of glaucoma and may lead to decreased urination in men with enlarged prostates. Decongestants may elevate blood pressure in some individuals and cannot be taken by persons on MAO inhibitor antidepressants.

The second generation antihistamine, Hismanal has been shown to cause irregular heart rhythms and even death when taken either in higher than recommended doses or in combination wit other medications, such a antibiotics, Erythromycin, Biaxin or the anti-fungal drugs, Fluconazole, Metronidazole, Ketoconazole and Itraconazole. Hismanal could also cause irregular heart rhythms in individuals with liver disease. Therefore, if you take Hismanal you must be certain that you do not take more than the recommended dose and that you do not take any other interacting medications. Consult your physician regarding this concern.

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