Can they overcome their checkered past? Open a medicine cabinet in the U. It might be in a pill or a gelcap. It might come in the form of an over-the-counter cold remedy or a prescription medicine such as Vicodin. Acetaminophen is everywhere. Some explanations involve chemical messengers of inflammation and pain. Others invoke aspects of neurotransmission in the brain and spinal cord. None of the proposals have accumulated enough supporting evidence to satisfy everyone.
This mystery might seem like minutiae in the grand scheme of things. Acetaminophen has been used clinically for many decades, with more than 27 billion doses sold in alone. So it is deceptively easy to take too much and cause a trip to the emergency room, permanent liver damage, or even death. Deaths from accidental acetaminophen poisoning are rare—approximately in the U. One mechanism researchers have kicked around is that acetaminophen blocks cyclooxygenase COX enzymes. These help to form prostaglandins, which are pain- and inflammation-mediating signaling molecules.
This would make acetaminophen similar to aspirin, or to ibuprofen and other nonsteroidal anti-inflammatory drugs NSAIDs. In the s, John R. It was an idea that stuck. Simmons , who led the COX-3 research. Today the prevailing hypothesis is that acetaminophen needs certain conditions to be a good COX inhibitor—namely, low levels of hydroperoxide-containing compounds Clin. Levels of these compounds vary throughout the body, so if this hypothesis is applicable to humans, it would explain a key laboratory observation about acetaminophen: It appears to work better in some types of cells and tissues than others.
As it happens, cyclooxygenase enzymes have two active sites—the peroxidase site, which activates the enzyme from its resting state, and the cyclooxygenase site.
Whereas all of the NSAIDs act at the cyclooxygenase site, acetaminophen works on the peroxidase site instead, preventing formation of a key tyrosine radical.
Vanderbilt University biochemist Olivier Boutaud , whose discoveries contributed to the peroxidase idea, is convinced that inhibiting the COX enzyme alone is enough to reduce fever and relieve pain.
They study acetaminophen metabolites and their effects on the central nervous system. One metabolite, AM, appears to act on COX enzymes as well as on the endocannabinoid system, both of which are involved in pain pathways J.
These channels also respond to certain cannabinoids. The TRP receptors actually elicit pain and itch in response to irritants such as capsaicin, so activating them might seem like a counterintuitive strategy for dulling pain. However, those with chronic conditions or a history of stomach ulcers should talk to a doctor before taking them. In rare cases, NSAIDs may cause serious side effects, with the risk increasing with long-term use and in people with a history of heart disease.
Examples of severe side effects include:. NSAIDs can also trigger stomach ulcers and bleeding. Factors that may increase these risks include:.
It helps ease pain while reducing inflammation. Both ibuprofen and Tylenol help alleviate pain and reduce fever. Both are effective for 4—6 hours. Ibuprofen is more suitable for moderate pain, rather than mild. It can also be more effective in treating inflammatory symptoms that may accompany a fever, such as sinusitis or backaches.
Since each drug works differently, it is generally safe to take them together. Tylenol has a variety of uses, including treating fever, muscle pain, and arthritis.
It is generally safe to use. Adults and children 12 years and over can take two caplets every eight hours, swallowed whole with water, and no more than six caplets in 24 hours. Tylenol products designed to help relieve cold symptoms or sinus discomfort contain another active ingredient, phenylephrine, which relieves congestion by shrinking blood vessels in the nasal passages. The reason it's important to know how much acetaminophen is in each Tylenol product and to follow the dosage directions carefully is that there's a very real danger of severe liver damage from taking too much acetaminophen at one time.
There are non-Tylenol medications that contain acetaminophen, including prescription narcotic pain relievers and cold-and-flu remedies which include acetaminophen as an ingredient. If you're taking any such product, it's important to not take OTC Tylenol at the same time as it may put your daily dose over the maximum daily dose recommended by the U. According to the FDA, adults should not take more than 4, milligrams mg of acetaminophen in a hour period.
The safe maximum dose per 24 hours for children under 12 is 90 mg. The FDA warns you shouldn't have more than three or more drinks per day. Despite the FDA recommendations, it is important to understand that your weight may also play a part in your maximum daily dose. Research suggests that taking 4, mg for extended periods can seriously damage the liver , especially if you're under pounds. As such, it best to limit your intake to the lowest effective dose and to stay closer to 3, mg per day as your maximum dose.
If you need to take higher doses for chronic pain, check with your healthcare provider first. Acetaminophen is contraindicated for use in people with severe liver impairment or severe liver disease. Current research suggests that the acetaminophen dose should be reduced to a maximum of 2, mg per day for heavy drinkers, people who are malnourished, and those who take chronic medications metabolized by the liver.
There are over different drugs metabolized by the liver, so be sure to check with your healthcare provider if you take chronic medications of any sort if you plan to use acetaminophen.
These include prescription, over-the-counter, nutritional, homeopathic, and recreational drugs. Dealing with chronic inflammation? An anti-inflammatory diet can help. Our free recipe guide shows you the best foods to fight inflammation. Get yours today! However, when you take a pain-relieving drug, there are some important questions:.
Different types of drugs for pain relief, such as ibuprofen, naproxen, and acetaminophen, can have different effects. Acetaminophen is an analgesic and an antipyretic drug.
It does not help reduce swelling or inflammation. Instead, acetaminophen works by blocking your brain from releasing substances that cause the feeling of pain. It relieves minor aches and pains from:. You may prefer acetaminophen over NSAIDs if you have high blood pressure or stomach ulcers or bleeding.
However, acetaminophen may cause liver damage and liver failure, especially at high doses. It can also increase the anti-blood-clotting effect of warfarin, a blood thinner. Instead, look into ibuprofen, naproxen, and aspirin. Some of the brands of these drugs include:. Read more: Guide to OTC anti-inflammatories ». NSAIDs work by blocking the formation of substances that contribute to fever, pain, and swelling. Reducing the inflammation helps reduce the pain that you feel.
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