Written By: Wafaa Shwaiky. RPH
What is Acetaminophen?
Acetaminophen or Paracetamol, a non-opiod analgesic without anti-inflammatory effects, was first used in medicine in 1893, but became very widely used after approval by the FDA in 1950, and has been approved as over-the-counter OTC in 1960.
Nowadays it is considered superior to Aspirin for its analgesic and antipyretic effects particularly for patients who are aspirin intolerant, have ulcers, difficulty in blood clotting, or in children.
Acetaminophen is available in many dosage forms and strengths for children and adults includingtablet, chewable tablet, soluble tablets, caplets, effervescent tablet, capsule, liquid, drops, granules (to be dissolved in water) and suppository. It is also available in combination with other drugs like Aspirin, Caffeine, Non-Steroidal Anti-Inflammatories (NSAIDs), Opioid, cold medications, and others.
Acetaminophen is available under different brand names as Tylenol® in USA and Panadol® inUK, TempraÒ, and many other generic preparations.
What is Acetaminophen used for?
It is used to reduce fever or to relieve mild to moderate pain as simple headaches, muscle aches, minor aches and pains associated with the common cold, backache, toothache, and menstrual cramps.
Acetaminophen is also useful in managing more severe pain, allowing lower dosages of additional NSAIDs, or Opioid analgesics to be used, so minimizing overall side-effects. Acetaminophen is generally well tolerated.
What is the mechanism of action of Acetaminophen?
It has been assumed that Acetaminophen acts by reducing production of prostaglandins*, which are involved in the pain and fever processes, by inhibiting the cyclooxegenase COX enzymewithin the central nervous system. This presumably accounts for its analgesic and antipyretic properties.
Acetaminophen is removed from the body mainly through the liver, and to a less extent through the kidney.
*Prostaglandins: a group of hormonelike substances produced in various tissues that are derived from amino acids and mediate a range of physiological functions.
What are the differences between the effects of Acetaminophen, and Aspirin?
There are important differences between the effects of Acetaminophen and those of Aspirin:
1- Unlike Aspirin Acetaminophen does not have peripheral anti-inflammatory effects, It does notrelieve the redness, stiffness, or swelling caused by rheumatoid arthritis, however, it may relieve the pain caused by mild forms of arthritis.
2- Aspirin reduces blood clotting, Acetaminophen does not.
3- Aspirin and the other NSAIDs commonly have detrimental effects on the stomach lining, where Prostaglandins serve a protective role, Acetaminophen is safe.
What is the most important information I should know about Acetaminophen?
Follow the instructions, and never exceed the prescribed dose. Taking more Acetaminophen could damage your liver or kidneyTake each oral dose with a full glass of water with or without food.Use Acetaminophen for up to 10 days for pain, or up to 5 days to treat a child's pain. If the symptoms do not improve, or if they get worse, stop using it and consult your doctor.Do not give Acetaminophen for adults or children for high fever, for fever lasting more than 3 days, or for recurrent fever without a doctor's supervision.Do not use Acetaminophen for children younger than 2 years without doctor consultation first.Do not give a child more than five doses in 24 hours unless directed to do so by a doctor.Make sure that you get a correct dose by measuring the liquid forms (drops or suspension) of Acetaminophen with a special dose-measuring spoon, cup, or dropper not with a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist where you can get one. Shake the liquid well before measuring if needed. The dose may be placed directly into a child's mouth or mixed with water or juice.
What are the special precautions I should take before using Acetaminophen?
Acetaminophen is listed by the American Association of Poison Control Centers as one of the most common drugs taken in overdose quantities either intentionally or accidentally, thereforeyou should:
Be aware of the Acetaminophen content of other OTC and prescription products, any Acetaminophen found in these products counts toward your total daily dose.Make sure if the children Acetaminophen product contains Aspartame, which may be dangerous to children with Phenylketonuria.Tell your doctor or pharmacist before taking Acetaminophen if:You are allergic to Acetaminophen or any other drugs, food, preservatives or dyes.You have, or have ever had liver or kidney disease, you may not be able to take Acetaminophen, or you require a dosage adjustment or special monitoring during treatment.You have a history of alcohol abuse.You are diabetic and you notice changes in your glucose levels while you are taking Acetaminophen, because it may cause false urine glucose test results.You are pregnant, Acetaminophen is in the FDA pregnancy category B. This means that it is unlikely to harm the fetus.You are breast-feeding a baby. Acetaminophen passes into breast milk. It appears to be safe for use during breast-feeding but should be avoided if possible.Your are taking any prescription and non-prescription medications.
What about taking Acetaminophen with other medications and Alcohol?
This drug may interact with many other drugs like:
Antiepileptic drugs as Barbiturates (Phenobarbital, Amobarbital, Secobarbital,Pentobarbital), Carbamazepin, and Phenytoin.Anti-tuberculosis drugs as Isoniazide, Rifampincine.Sulfinpyrazone (a drug used to treat gout).Alcohol beverages should not be taken with Acetaminophen, if so dose must be adjusted.
Tell your health care professional about all other medicines you are taking, including non-prescription medicines, nutritional supplements, vitamins, or herbal products.
What is the right dose of Acetaminophen?
The following information includes only the average doses of Acetaminophen. If your dose is different, do not change it unless your doctor tells you to.
The number of dose units (capsule, tablet, ml, suppositories and other) that you take depends on the strength of the medicine. Also, the number of doses you use each day and the time allowed between doses depend on the strength of the medicine.
For pain or fever:
Adults and teenagers: 325 or 500 mg every three or four hours, 650 mg every four to six hours, or 1000 mg every six hours as needed. The total dose should not be more than 4000 mg (for example, eight 500–mg tablets) a day. The maximum dose for adults is 1 gram (1000 mg) per dose and 4 grams (4000 mg) per dayChildren dose is based on the child's age:Infants up to 3 months of age: 40 mg every 4 hours as needed.Infants 4 to 12 months of age: 80 mg every 4 hours as needed.Children 1 to 2 years of age: 120 mg every 4 hours as needed.Children 2 to 4 years of age: 160 mg every 4 hours as needed.Children 4 to 6 years of age: 240 mg every 4 hours as needed.Children 6 to 9 years of age: 320 mg every 4 hours as needed.Children 9 to 11 years of age: 320 to 400 mg every 4hours as needed.Children 11 to 12 years of age: 320 to 480 mg every 4 hours as needed.
What happens when the dose is missed?
If you are taking Acetaminophen on a regular schedule, take the missed dose as soon as you remember. Wait the prescribed amount of time or as directed in the package labeling before taking another dose. Do not take a double dose.
If you are taking it on an as-needed basis, missing a dose is not usually a problem. Take the dose as soon as you remember if you need it, and do not take another dose for the amount of time prescribed or as directed in the package labeling.
What side effects can Acetaminophen cause?
|The most common side effects are upset stomach and skin rash. Although side effects from Acetaminophen are not common, they can occur.
Stop taking Acetaminophen and seek emergency medical attention if you experience one of the following symptoms:
Difficulty breathing, closing of your throat, swelling of your lips, tongue, or face, or hives.Yellowing of the skin or eyes, nausea, abdominal pain or discomfort, unusual bleeding or bruising, severe fatigue.
What about Acetaminophen overdose?
Acetaminophen overdose may lead to liver damage and in serious cases to death. The FDA has launched an educational campaign on over the counter drugs, like Acetaminophen, to warn of the deadly Acetaminophen side effects that account for 13,000 emergency room patients and 100 deaths every year. Due to the non-prescription strength labeling that over the counter Acetaminophen products are advertised with, it is easy to equate non-prescription as being safer.
Consumers are warned to avoid using multiple medications that have the same ingredients in them to avoid instances like Acetaminophen side effects. In addition, consumers should be aware of the risks of using over the counter medications alongside certain prescription drugs.
Overdose Symptoms include nausea, vomiting, diarrhea, abdominal pain, sweating, seizures, confusion, and an irregular heartbeat.
After all this information is it safe to take Acetaminophen?
Although Acetaminophen is considered one of the safest medicines around, but a study published recently in the Journal of the American Medical Association shows that use of maximum daily dose of Acetaminophen can affect liver enzymes. Experts see the new results as a warning, but not as a reason to stop taking Acetaminophen.
September 1st, 2006
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