Acetaminophen is used to relieve minor aches and pains such as headaches, muscle aches, backaches, toothaches, menstrual cramps, arthritis, and the achesand pains that often accompany colds. It is also used to reduce fever.

Acetaminophen is available without a prescription and is sold under various brand names, including Tylenol, Panadol, Aspirin Free Anacin, and Bayer SelectMaximum Strength Headache Pain Relief Formula. Many multi-symptom cold, flu,and sinus medicines also contain acetaminophen.

Studies have shown that acetaminophen relieves pain and reduces fever about as well as aspirin. But differences between these two drugs exist. Acetaminophen is less likely than aspirin to irritate the stomach. However, unlike aspirin, acetaminophen does not reduce the redness, stiffness, or swelling that accompany arthritis.

Acetaminophen has few side effects. The most common one is lightheadedness. Some people experience trembling and pain in the side or the lower back. Allergic reactions are rare. Anyone who develops symptoms such as a rash, swelling, or difficulty breathing after taking acetaminophen should stop taking the drug and get immediate medical attention. Other rare side effects include yellow skin or eyes, unusual bleeding or bruising, weakness, fatigue, bloody or black stools, bloody or cloudy urine, and a sudden decrease in the amount of urine.

The usual dosage for anyone over age 12 is 325-650 mg every 4-6 hours as needed. No more than 4000 mg should be taken in 24 hours. Anyone who drinks threeor more alcoholic beverages a day should check with a physician before usingthis drug because there is a risk of liver damage from combining large amounts of alcohol and acetaminophen. People who already have kidney or liver disease or liver infections should also consult a physician before using the drug, as should women who are pregnant or breastfeeding. For children ages 6-11 years, the usual dose is 150-300 mg, three to four times a day. For younger children, a physician's advice should be asked.

Patients should not use acetaminophen for more than 10 days to relieve pain (5 days for children) or for more than 3 days to reduce fever, unless directedto do so by a physician. If symptoms do not go away--or if they get worse--medical attention is necessary.

Patients must avoid using two different acetaminophen-containing products atthe same time. Overdoses of acetaminophen may cause nausea, vomiting, sweating, and exhaustion. Very large overdoses can cause liver damage. In case of anoverdose, get immediate medical attention.

Acetaminophen may interact with several other medicines. If this happens, theeffects of one or both of the drugs may change or the risk of side effects may be greater. Among the drugs that may interact with acetaminophen are alcohol, nonsteroidal anti-inflammatory drugs (NSAIDs) such as Motrin, oral contraceptives, the antiseizure drug phenytoin (Dilantin), the blood-thinning drugwarfarin (Coumadin), the cholesterol-lowering drug cholestyramine (Questran),the antibiotic Isoniazid, and zidovudine (Retrovir, AZT). Check with a physician or pharmacist before using acetaminophen with any other medicine. Smoking cigarettes may also interfere with the effectiveness of acetaminophen. Smokers may need to take higher doses of the medicine, but should not take more than the recommended daily dosage unless told by a physician to do so.

Acetaminophen interferes with the results of some medical tests. Before having medical tests done, check to see whether taking acetaminophen will affect the results. Avoiding the drug for a few days before the tests may be necessary.

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