In a recent study published in the Canadian Medical Association Journal (CMAJ),and list five facts to know about the proper use of antihistamines for allergies:
- Antihistamines are among the most commonly and incorrectly used medicines worldwide.
Antihistamines are best used to relieve symptoms of hay fever and outbreaks of hives, but not for asthma, eczema, coughs or insomnia.
- First-generation antihistamines are associated with substantial and sometimes fatal side effects.
Antihistamines with diphenhydramine, chlorpheniramine or hydroxyzine are first-generation antihistamines that can cause drowsiness and affect cognitive functions such as school performance. In the majority of the United States, one is considered to be driving under the “influence” if taking one of the sedation first generation antihistamines. Overdosing has also been associated with mortality and they are potentially dangerous for both young and older people.
- Newer antihistamines are safer, as affordable and as effective as first-generation antihistamines.
Later-generation antihistamines are proven to be more effective and last longer with less side-effects like drowsiness.
- Antihistamines should not be used instead of epinephrine to treat anaphylaxis.
Oral drugs can be used together with epinephrine injections to treat anaphylactic reactions, but they are not a substitute.
- Most antihistamines are safe to use during pregnancy and breastfeeding.
Medical research has shown that antihistamines at standard doses do not harm fetuses during pregnancy and may be used during breastfeeding. They are also safe for children to use.
- Antihistamines can increase ocular dryness in patients predisposed to “dry eye” conditions.
Oral histamine H1-receptor antagonists are the most frequently prescribed class of agents used for allergic rhinitis management. Unlike first-generation antihistamines, second-generation agents are highly selective peripheral histamine blockers that demonstrate little or no side effects upon the central or autonomic nervous systems. While second-generation agents are actually "minimally-sedating," they still exhibit a tendency to reduce tear volume and may exacerbate symptoms of ocular irritation, itching and dryness (Reference). In addition hormonal changes such as perimenopausal ad postmenopausal and history of refractive surgery (Reference).
7. Intranasal treatments have been shown to improve ocular symptoms as well.
Consider the use of intranasal steroids for severe nasal congestion or the using a nonsteroidal, Sinusol® Breathe Easy. (www.DRBRX.com)
Nye, M., S. Rudner and L. Bielory (2013). "Emerging therapies in allergic conjunctivitis and dry eye syndrome." Expert Opin Pharmacother 14(11): 1449-1465.
Hom, M. M., A. L. Nguyen and L. Bielory (2012). "Allergic conjunctivitis and dry eye syndrome." Ann Allergy Asthma Immunol 108(3): 163-166