Seasonal Allergies : Side Effects, Extracts for Allergy Serum

by Food and Drug Administration (FDA)

(Page 3 of 3)

Q: My hay fever strikes every spring and fall. I sneeze, my eyes water, and my throat itches. How do I choose the best medicine for me?

A: For typical hay fever symptoms, three over-the-counter options can help: oral antihistamines, decongestants (both oral and nasal sprays), and a nasal spray containing cromolyn sodium.

Brands such as PediaCare, Robitussin, Comtrex, and Benadryl, as well as generic store brands, contain antihistamines, either chlorpheniramine or diphenhydramine. These drugs are effective for runny noses, sneezing, and itching, but can make you drowsy.

"If the OTC antihistamines are effective in relieving symptoms but are too sedating, a newer less sedating antihistamine can be obtained by prescription," says Linda Hu, M.D., a medical reviewer in FDA's division of OTC drugs. Antihistamines work on a runny nose, but not as well on a stuffy one, so many brands combine an antihistamine with a decongestant (for example, pseudoephedrine). Decongestants can also be found in fast-acting nasal sprays, but these may have a rebound effect and after about three days they'll make your nose even more congested. They are better used for a short-lived cold than an ongoing allergy. One nasal spray that doesn't cause a rebound effect is Nasalcrom (cromolyn sodium). This drug is helpful to prevent your symptoms if started a few days before the allergy season begins and taken continuously. It causes few side effects and will not make you drowsy.

Remember that it's the active ingredient that is important, and many products contain more than one. Read the labels to make sure you're not combining drugs with the same ingredients. Look at the ingredients in the drug product and choose the type of ingredient that will best treat the symptoms you have.

Q: My job requires a lot of driving. Is it safe to take an antihistamine in the morning before I go to work?

A: Probably not. Antihistamines may affect your ability to drive or use machinery even if you don't feel sleepy.

"Drowsiness is the most common side effect of antihistamines and may be a problem for users who need to remain alert," says Hu. "Also, alcohol should be avoided because it may increase the drowsiness caused by antihistamines. If you need to be alert, some prescription antihistamines are less sedating."

Q: I have emphysema and high blood pressure. Can I take an over-the-counter allergy medicine?

A: Antihistamines should not be used by anyone with breathing problems such as emphysema or bronchitis, anyone with glaucoma, by those taking sedatives or tranquilizers, or anyone with difficulty in urination unless directed by their doctors. These drugs dry up secretions and may cause urinary retention and drowsiness, according to Hu.

Antihistamines may also cause dryness of the mouth and eyes and blurred vision.

Decongestants, which are in many OTC allergy medicines, can raise blood pressure. Ask your doctor what, if anything, you can take. Decongestants should not be used by people with heart disease, thyroid disease, or diabetes unless a doctor says it's OK. If you're taking a drug containing an MAO inhibitor (sometimes used to treat depression), never use a decongestant.

Q: I've tried every medicine on the shelves, and I'm still miserable each spring. What else can I do?

A: See your doctor. There may be prescription drugs that are more helpful to you, you may need allergy testing or shots, or your symptoms may be caused by something else entirely.

Dangerous Side Effects

Two prescription antihistamines, first touted for their effectiveness without causing drowsiness, are now known to have dangerous side effects. Seldane (terfenadine), and Hismanal (astemizole) have been shown to react with a number of other medications to cause life-threatening cardiac arrhythmias.

Seldane's manufacturer, Hoechst Marion Roussel, Kansas City, Mo., withdrew the medication along with Seldane-D (terfenadine, pseudoephedrine) from the market voluntarily last winter.

Patients taking antibiotics, antifungal medications, and some medications to treat HIV infection should talk to their doctors about the risks of taking any products containing terfenadine or Hismanal (astemizole).

Extracts for Allergy Serum

FDA has been working to standardize the biological extracts used to test and treat patients with allergies.

"Extracts prepared from natural sources such as pollens, animals and foods that trigger allergic reactions will vary in potency if they are not standardized," says Paul Turkeltaub, M.D., director of FDA's division of allergenic products and parasitology in the Center for Biologics Evaluation and Research. "Without standardization, each extract is an unknown. One batch could be stronger than the next. It makes it more difficult to treat patients and it also raises safety concerns."

Manufacturers are working to standardize extracts so they are consistent in potency from lot to lot. Currently, FDA has approved standardized allergy extracts for short ragweed, bee and other stinging insect venoms, dust mites, and cats.

Moreover, FDA is requiring that eight grass and pollen extracts be standardized. "The availability of the grass and pollen extracts will enhance their safe and effective use in diagnosis and treatment of grass allergies," says Turkeltaub. Nonstandardized extracts of cockroach (an important cause of inner-city asthma), giant ragweed, mold, peanuts, dog dander, and feathers are proposed for future standardization.

No allergy extracts are approved for sensitivity to foods, latex, or chemicals such as hair sprays, perfumes or cigarette smoke.

About the Author

www.fda.gov
FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.