TheraFlu relieves symptoms associated with colds, upper respiratory infections and allergies, according to Drugs.com. It contains a decongestant, cough suppressant, analgesic and antihistamine. These ingredients relieve symptoms of sinus congestion, runny nose, sneezing, pain and cough.
The decongestant in TheraFlu reduces swelling in the nasal passages by constricting blood vessels, explains Drugs.com. The antihistamine blocks histamine, which is responsible for allergic symptoms such as sneezing and watery eyes. The analgesic and cough suppressant act in the brain to decrease pain and reduce cough.
Side effects of TheraFlu include drowsiness, headache, nausea, dizziness and difficulty sleeping, reports WebMD. Doctors who prescribe TheraFlu judge the benefit to outweigh the side effects. Serious side effects, however, need to be reported to a doctor. These include irregular heartbeat, mental changes, tremors, weakness and problems with urination. Symptoms of rash, trouble breathing and itching or swelling of the face, tongue or throat indicate a serious allergic reaction, and medical attention should be sought immediately.
Before taking TheraFlu, patients should advise doctors of all allergies and other medications they are taking, instructs WebMD. Patients should also inform doctors of their medical history, especially problems of diabetes, glaucoma, high blood pressure, liver disease and hyperthyroidism. Other issues to report are heart problems, kidney problems, trouble urinating and alcohol use or abuse.