About Allergy Relief Antihistamines

ANTIHISTAMINES-OVER THE COUNTER

Many former prescription drugs are now available over the counter (OTC) in the form of pills, nasal sprays, and eye drops. Americans spend approximately $2 billion a year on the grow­ing arsenal of OTC allergy medications and often try them be­fore seeing a doctor.

Be wary of OTC drugs. Buy and use them with as much care and caution as you would a prescribed medication. According to Consumer Reports on Health, one in three persons who takes OTC antihistamines also takes other drugs at the same time.

If you know your pharmacist, ask him to enter the medica­tion, as well as any drug allergies you may have, into the phar­macy's computer. It should warn about potential drug interactions and possible allergic reactions.

A consumers' book on medicines is an excellent resource. It lists everything you need to know about each drug, including purpose, duration, possible side effects, dosages, and interac­tions to avoid. (The Complete Drug Reference is available in most libraries or from Consumer Reports Books. Send $39.95 plus $3.50 for shipping and handling to Box 10637, Des Moines, IA 50336-0637, or call [515] 237-4903.)

If you're allergic to aspirin, for example, you would need to know that Alka-Seltzer Plus Nighttime Cold contains aspirin, and that ibuprofen (Advil, Motrin-IB) and naproxen (Aleve) can trigger reactions in aspirin-sensitive persons.

Also, alcohol in cough syrups could combine with antihista­mines to cause extreme drowsiness, and you could be getting a double dose of antihistamines when you take them with Alka-Seltzer Plus Cold, Contac Severe Cold Formula, or sleeping aids Nytol and Sominex—all of which contain antihistamines.

Another point to remember is that antihistamines only help allergies. If you have some other condition, such as sinusitis, an­tihistamines can prolong the infection by drying out the sinuses and preventing drainage.

Ask your physician for advice before using any OTC drug you haven't used before. And always read the package insert or label carefully and follow instructions.

Here's what to look for:

• What the product does (it should say "allergy relief" or similar words)

•     List of active ingredients (are you allergic to any ingredients? Are you taking another drug with the same ingredient and getting a double dose?)

•     Instructions for use (dosage; when and how to take it)

•     How the drug should be stored

•     Drug interaction precautions (does the drug in­teract with other medication or with any food or beverage?)

•     Tamper-prevention safeguards (don't take any package that shows cuts, tears, or the slightest imperfection)

•     Expiration date (never use an expired drug)

•     Warnings (specific medical conditions, including pregnancy, that might preclude taking the drug; possible side effects; when to stop using the product)

Most OTC allergy drugs contain both an antihistamine, to block the action of histamine, and a decongestant, to "unstuff" your nose. Some familiar brand-name products that contain both medications are Allerest, Actifed, Dimetapp, and Tavist-D. Tavist-1, Dimetane, Benadryl 25, and Chlor-Trimeton contain only antihistamine; Actifed Allergy, Sudafed, Propagest, and Efidac/24 contain only a decongestant; Tylenol Allergy Sinus contains both, plus a pain reliever.

The Johns Hopkins Medical Letter suggests avoiding multi-ingredient remedies and just taking the OTC drug with the sin­gle active ingredient you need: an antihistamine such as chlor­pheniramine for allergies, a decongestant such as phenylephrine for a stuffy nose, an antitussive such as dextromethorphan for a dry cough, and an expectorant such as guaifenesin to help loosen a cough. This makes good sense. Why load yourself with unnecessary medications?

 

Over-the-counter medications can offer temporary relief, but they do have side effects. Antihistamines can cause dry mouth and drowsiness along with impaired visual, mental, and motor skills. For dry mouth, sip water often during the day, chew sug­arless gum (gum with sugar can actually worsen symptoms), and rinse your mouth with a solution containing car-boxymethylcellulose, a saliva substitute.

Decongestants can cause irritability and insomnia, and both antihistamines and decongestants can increase vaginal dryness and dry-eye symptoms.

Timing can be crucial to getting results. If you're visiting Aunt Ella and her four cats, for instance, or you're en route to a hayride during pollen season, plan ahead. Take antihistamines for three to four days in advance to build up blood levels. If that's not possible, take a tablet at least thirty minutes before the anticipated exposure. Relief usually begins within half an hour and peaks at forty-five to sixty minutes. Remember: One pill taken early can prevent the need for many pills later.

Your body may eventually build up a tolerance to the drug so that it's no longer effective. When that happens, a switch to another drug may help, or it may be time to go back to your doctor.

ANTIHISTAMINES-DOCTOR PRESCRIBED

Antihistamines fall into several different groups with varying properties. If one type doesn't work for you, another type might. The only way to know if an antihistamine will help you is to try it.

The newer nonsedating antihistamines require a prescrip­tion and cost more, but they have fewer side effects than "first-generation" antihistamines and are definitely the agents of choice. Examples are loratadine (Claritin), cetirizine (Zyrtec), fexofenadine (Allegra), and acrivastine (Semprex-D). These drugs block the production of histamine, which triggers allergy attacks, and come in many forms: twelve- or twenty-four-hour pills, syrups, even tablets that dissolve on the tongue without water.

When followed by the letter D (e.g., Claritin-D), the medica­tions also have a decongestant, usually pseudoephedrine. This decongestant can act as a stimulant, speeding up heart rate and blood pressure, so it's wise not to take it before bedtime. Avoid it, too, if you have prostate problems or glaucoma.

Most "second-generation" antihistamines can be classified as nonsedating, although one study reported that Zyrtec and Semprex-D caused slight drowsiness in 10 percent of the pa­tients studied. Second-generation antihistamines are far less se­dating than their predecessors, but their safety in pregnancy hasn't been established. Women, in fact, should use extreme caution taking any drugs during pregnancy.

Second-generation antihistamines have proven to be effec­tive and well tolerated, with a low risk of side effects. The Schering Corporation, makers of Claritin, one of the most popu­lar new medications, claims: "Side effects (of Claritin) occurred about as often as they did with placebo or sugar pill. These were headache, occurring with 12 percent of people, drowsiness 8 percent, fatigue 4 percent, and dry mouth 3 percent."

Terfenadine (Seldane) was removed from the market in 1998 because of rare and dangerous side effects. Astemizole (His­manal) was pulled from the market in June 1999 for similar rea­sons. Also, irregular heartbeats can occur when Hismanal interacts with other medications such as the antibiotic ery­thromycin (Erythrocin) or the antifungal drug ketoconazole (Ni­zoral), or when simply washed down with grapefruit juice. Be sure your doctor knows every drug you're taking.

Azelastine (Astelin), another option, is a prescription anti­histamine nasal spray that treats runny noses at the source and also helps with congestion. The patient absorbs less medication than from a pill, and the medicine works a few minutes after spraying and lasts up to twelve hours.

But Astelin can cause drowsiness, and should not be taken with other drugs, especially alcohol and medications that slow the central nervous system, such as codeine, phenobarbitol, and Restoril. Cimetidine (Tagamet) or ketoconazole (Nizoral) should not be taken with Astelin, either.

Nasal sprays can offer relief of runny, stuffy noses, but are not as effective as oral medication for itchy, watery, red eyes.

Don't take any antihistamine if you have glaucoma, a persis­tent cough, or an enlarged prostate.

In May of 1994, the Reuters news service carried a story linking several of the new antihistamines to cancer growth in mice. The National Cancer Institute promptly responded that the known benefits of the drugs outweighed the known harm, and an FDA advisory committee found it "unlikely that these drugs produce tumors in humans." The furor quickly died down.

When your doctor prescribes an antihistamine, be prepared to ask some questions:

•    What will this drug do for me?

•    What's the best way to take it? (With fruit juice? With meals?)

•    What's the best time to take it?

•    How much should I take, how often, what's the maximum daily dose, and what if I miss a dose?

•    Should I take it even if I'm not having symptoms?

•    What foods, drinks, or activities should I avoid when I take it? (Alcohol and tranquilizers increase the sedative effects.)

•    Will it interact with other medication I'm taking?

•    What side effects should I expect, which should I ignore, and which should I call you about?

•    If relevant: Will this drug affect my pregnancy or breast-feeding?

• Is a generic equivalent available and appropriate?

Short-acting antihistamines can usually be taken three to four times a day, as needed, while time-release pills are better suited to chronic use. Most of the newer antihistamines are available in once-daily dosages that take effect within half an hour and last for twenty-four hours.