Fexofenadine hydrochloride (brand names include Allegra and Telfast) is an antihistamine drug used in the treatment of hayfever and similar allergy symptoms. It was developed as a successor of and alternative to terfenadine (brand names include Triludan and Seldane), an antihistamine with potentially serious contraindications. Fexofenadine, like other second and third-generation antihistamines, does not readily enter the brain from the blood, and so causes less drowsiness than first-generation histamine-receptor antagonists.
When you come in contact with something you're allergic to, a chain reaction begins inside your body. During this chain reaction, specialized cells release powerful chemicals. Some of these chemicals can trigger swelling of the nasal passages leading to nasal congestion (a "stuffy nose"). Other chemicals, such as histamine, can cause sneezing, itching, and irritation.
Allegra is classified as an antihistamine. Allegra blocks the effects of histamine (hence its classification as an antihistamine). This can relieve allergy symptoms. However, since histamine is not the cause of nasal congestion, Allegra will not help open nasal passages.
Is Allegra Safe During Pregnancy?
Allegra® (fexofenadine hydrochloride) is considered a pregnancy Category C medicine by the U.S. Food and Drug Administration (FDA), which means that Allegra has not been studied in pregnant women. However, studies on pregnant animals imply that Allegra could potentially cause harm to an unborn child.
During testing with animals, Allegra did not show any potential for birth defects. However, with doses three times the recommended amounts, Allegra did cause a slowing in fetal weight gain and survival. It is important to note that animals do not always respond to medicines in the same way that humans do.
Allegra and Pregnancy Category C
The U.S. Food and Drug Administration (FDA) uses a pregnancy category system to classify the possible risks to a fetus when a specific medicine is taken during pregnancy. Pregnancy Category C is given to medicines that create side effects in the fetus in animal studies, but no human studies in pregnant women have been done. A pregnancy Category C medicine may still be prescribed for pregnant women if the healthcare provider believes that the benefits to the pregnant woman outweigh the possible risks to the unborn child.
If you are pregnant or may become pregnant while taking Allegra, let your healthcare provider know. Your healthcare provider will consider both the benefits and risks of Allegra during pregnancy before making a recommendation for your particular situation. It is possible he or she may recommend a lower dose of Allegra or a switch to an allergy medicine that is a pregnancy Category B medicine.
