Tylenol is a common over-the-counter painkiller used worldwide. It’s the name-brand version of generic acetaminophen (US name) or paracetamol (name outside of the US). Both generic names are taken from the full chemical name N-acetyl-para-aminophenol. It’s sometimes referred to as APAP. The drug appears both in tablets by itself as well as combined into many other solid and liquid medicines for colds, flus, fevers, and headaches. These include cough syrups and sleep aids. They are labelled and sold for children and adults.
Acetaminophen is also a common ingredient in many stronger painkillers. It is frequently mixed with stronger opioid  painkillers such as codeine  and hydrocodone . The hydrocodone and acetaminophen mix is generally called Vicodin .
Since acetaminophen is such a commonly used compound that is often a major ingredient in medicines that do not require a prescription, you may be surprised that the toxic effects of acetaminophen are the #1 cause for acute liver failure in the US and UK. The medicine breaks down in the liver, creating a metabolite called N-acetyl-p-benzoquinoneimine (NAPQI)  that poisons the liver. NAPQI causes direct damage to cells, and further depletes the body of the essential antioxidant glutathione . NAPQI from acetaminophen metabolism can also damage the kidneys. Acetaminophen poisoning can result in death.
Usually extensive liver damage from acetaminophen is caused by exceeding recommended dosages. Although it is relatively rare, a few people can suffer from liver damage even from normal dosages. Toxic poisoning of the liver due to acetominophen is the most common cause of acute liver failure in the Western world. It accounts for the majority of drug overdoses in the US, UK, Australia, and New Zealand.
Acetaminophen Usage for Children
Many parents use acetaminophen as an analgesic (painkiller) and fever reducer for their children as it is widely known that aspirin  (also known as acetylsalicylic acid or salicylic acid, one of a class of salicylate drugs) can cause not only allergic reactions and excessive bleeding, but also Reye’s syndrome  if used when a child has a viral disease such as flu, chickenpox, diarrhea, or colds. Reye’s syndrome can lead to severe brain and liver damage that may be fatal. About 30% of those afflicted die. It almost exclusively occurs in children, with very few cases reported in adults. After the US CDC  spread the word starting in 1980 about the connection between aspirin, viral illnesses, and Reye’s syndrome, the number of Reye’s syndrome cases in the US fell from 555 in 1980 to about 2 per year in 1994 and thereafter.
Acetaminophen has its own dangers in children, however. A study published in the September 19, 2008, issue of The Lancet involving over 200,000 children taking acetaminophen found that the use of the drug causes an increased risk of asthma. Moderate usage increased the risk by 61% and heavy usage increased it by more than 200%. The study also found that using acetaminophen during the first year of a child’s life increases the risk of rhinoconjunctivitis  (allergic eye inflammation) by 48% and of eczema  by 35%. Higher dosages also showed higher elevations in these risks, too.
Glutathione May Reduce Harm from Acetaminophen
If acetaminophen is going to be used as a painkiller, patients and parents should consider also supplementing the diet with safe substances that can support glutathione production to protect the body and especially the liver. The human digestive system cannot absorb glutathione well directly, so direct supplementation with it is not effective. Increased intake of the amino acid cysteine or of the relatively expensive dietary supplement SAMe (S-adenosyl methionine ) can achieve this effect of increased glutathione production.
N-acetylcysteine (NAC) is one of the least expensive absorbable dietary supplements available that can boost glutathione production. Further, it also has the benefit of helping to break up and dissolve mucus in the body. This may be particularly beneficial for patients who are taking acetaminophen as a painkiller for a cold, flu, or other respiratory malady that causes excess mucus.
Some of the least expensive sources for N-acetylcysteine supplements are online dietary supplement vendors. Swanson Health Products sell their N-Acetyl Cysteine 600 mg 100 Caps  product for $6.49 per bottle at the time of this update. That works out to a year’s supply of 600mg per day for about $25.
Another online vitamin vendor is Puritan’s Pride. Their 600mg NAC capsules  are available in 120 capsules bottles via their buy one get two free sale for $32.99 for 3 bottles.
NAC available from other reputable vendors includes Life Extension’s 600mg bottle of 60 capsules . The price typically ranges from about $10 to $15 per bottle, depending upon quantity.
NAC contains sulfur. Some say it smells like rotten eggs, not something that is pleasant to most people. However, my personal experience with bulk NAC powder (see Review: 1FAST400 N-Acetylcysteine (NAC) Bulk Powder ) is that the scent is so mild that some people can’t even detect it. In any case, NAC capsules are easily swallowed with no objectionable taste and do not generally cause digestive discomfort or other problems. Daily dosages of up to 1200mg are widely regarded as safe for long-term use.
Much larger dosages have been studied. One study with AIDS patients involved dosages up to 8000mg per day without significantly harmful effects. Very extreme dosages studied in a mouse model showed that such extreme NAC dosages could cause blood pressure increases and lung problems similar to that experienced from long-term hypoxia (low oxygen levels). However, other research in humans with more reasonable dosages suggest that this effect is not likely to be found in humans.
Other Benefits of N-Acetylcysteine (NAC)
Some naturopathic and homeopathic doctors, such as Dr. Mark Stengler, are recommending their patients supplement with NAC on a routine basis. Such recommendations include taking NAC at 600mg per day on a daily basis and during flu season to increase the supplement to 1200mg per day. When ill with a flu or cold, they recommend up to 2400mg of NAC per day during the illness.
A study of 262 subjects in Italy involved subjects taking two 600mg NAC tablets daily during six months overlapping the winter flu season. The study concluded that NAC significantly reduced flu symptoms. 79% of the people who were taking placebo pills developed evident flu symptoms, but only 25% of those taking NAC developed evident flu symptoms. Over the cold and flu season, those taking NAC had 1/3 to 1/2 of the flu-like symptoms of those taking the placebo pills. Of the 10 subjects who did not end up bedridden due to being sick during the study, 9 of them were taking NAC.
NAC is also recommended for heavy metal detoxification, particularly for people who have recently had amalgam (mercury alloy) fillings removed. The increased glutathione levels in the body help eliminate traces of mercury and other heavy metals. The thiol groups in the cysteine are particularly good at binding to mercury, lead, cadmium, and other heavy metals.
Hangovers are another common reason for people to be taking acetominophen. The combination of alcohol and acetaminophen is particularly likely to cause liver damage. NAC supplementation may not only help reduce the chances of liver damage, but also help remedy the hangover. The cysteine in NAC helps break down acetaldehye , the chemical responsible for alcohol-induced hangovers. NAC supplementation in combination with vitamin B1 (thiamine) is particularly effective at reducing the severity of hangovers .
Another use of NAC is as a supplement to help AIDS patients. A study of 204 AIDS patients suggests that high NAC dosages of 3200mg to 8000mg per day caused an increase in glutathione levels. After two years of the study, those who chose to take NAC after this had approximately twice the survival rate as the subjects who didn’t take it. The study discussion contends that HIV-1 causes the production of a toxic protein known as Tat which reduces glutathione levels significantly. Another possible cause noted was that patients using AIDS drugs AZT or nucleosides had significantly lower glutathione levels than AIDS patients who were not using them, suggesting that the drugs may have further depleted glutathione. NAC counteracts these reductions in glutathione, improving health.
Some research has been done that suggest NAC may help inhibit cancer growth two ways. One is by reducing the tendency of cancer-causing compounds to attach to DNA. Another is by reducing the spread of free radicals that encourage the reproduction of more cancer cells.
Finally, NAC is even being studied for use in the treatment of obsessive-compulsive disorder (OCD). Yale University is running this study which uses a dosage of 3000mg per day. They are still recruiting study participants. Click here  if you’re interested in learning more about this study, or email [email protected]  for more information. You can read more about the use of NAC for OCD and a related condition involving compulsive hair pulling called trichotillomania in our article N-Acetylcysteine (NAC) Reduces Hair Pulling Compulsion and May Also Be Useful for OCD .
In short, NAC has a surprising number of benefits. Most of them can be tied to the increase in glutathione levels which are what helps NAC remedy the toxic effects of acetaminophen.
Pets Can Be Harmed by Acetaminophen, too
Be sure to keep your supply of acetaminophen based medicines secure from pets, too. Acetaminophen is deadly to cats and snakes. In cats, it causes death by asphyxiation. Dogs can suffer deadly liver damage much like humans. If your pets somehow eat some acetaminophen, get them to the vet as quickly as possible. In the meantime, if you can get them to eat it, N-acetylcysteine may help prevent feline death from small dosages of acetaminophen and prevent extensive liver damage in dogs.
Be Cautious With Acetaminophen
If you’re going to use acetaminophen, exercise some caution. Be especially cautious to avoid exceeding safe daily dosages and to avoid extended daily usage. Otherwise, you run a significantly elevated risk of liver damage.
For young children, especially those one year old or less, we suggest that you avoid using acetaminophen and aspirin if at all possible.
For older children and adults, acetaminophen is less likely to caues problems but the risk of liver damage still exists. To help reduce that risk and further aid recovery from colds and flus which often lead to the usage of acetaminophen-based medicines, consider taking 600mg per day of NAC for adults year-round even when you are well. Increase the dosage to between 1200mg and 2400mg spread over two to four doses per day when you’re taking acetaminophen or are sick with a flu-like or cold-like illnesses. If you find this helps, consider taking 1200mg per day of NAC during the flu and cold season in your area.
When you’re having minor surgery or dental work or require stronger painkillers than plain acetaminophen, be sure to keep some NAC handy in case you use codeine and Vicodin as they are almost always mixed in tablets with acetaminophen. This will help reduce the chances of acetaminophen in those medicines causing liver damage, too.
These statements have not been evaluated by the Food and Drug Administration. The products mentioned in this post are not intended to diagnose, treat, cure or prevent any disease.