ACETAMINOPHEN

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Acetaminophen is used to reduce pain and fever. Unlike NSAIDs (nonsteroidal anti-inflammatory drugs), it lacks anti-inflammatory activity. Acetaminophen is available by itself or in nonprescription and prescription-only combination products used to relieve pain and the symptoms associated with colds and flu.

Safetychecker Summary for Acetaminophen
(for details about the summarized interactions, read the full article)

May be Beneficial: Side effect reduction/prevention—Taking these supplements may help reduce the likelihood and/or severity of a potential side effect caused by the medication.	N-acetyl cysteine Milk thistle*
May be Beneficial: Supportive interaction—Taking these supplements may support or otherwise help your medication work better.	Vitamin C*
Check: Other—Before taking any of these supplements or eating any of these foods with your medication, read this article in full for details.	Schisandra
Depletion or interference	None known
Reduced drug absorption/bioavailability	None known
Adverse interaction	None known

Interactions with Dietary Supplements

N-acetyl cysteine (NAC)
Hospitals use oral and intravenous N-acetyl cysteine (NAC) to treat liver damage induced by acetaminophen overdose poisoning.¹ NAC is often administered intravenously by emergency room doctors. Oral NAC appears to be effective for acetaminophen toxicity.

An uncontrolled trial compared intravenous NAC with oral NAC in children with acetaminophen poisoning and found that both methods were equally effective in reversing acetaminophen-induced liver toxicity.² However, acetaminophen toxicity is a potential medical emergency, and should only be managed by qualified healthcare professionals.

Vitamin C
Taking 3 grams vitamin C with acetaminophen has been shown to prolong the amount of time acetaminophen stays in the body.³ This theoretically might allow people to use less acetaminophen, thereby reducing the risk of side effects. Consult with a doctor about this potential before reducing the amount of acetaminophen.

Interactions with Herbs

Milk thistle (Silybum marianum)
Silymarin is a collection of complex flavonoids found in milk thistle that has been shown to elevate liver glutathione levels in rats.⁴ Acetaminophen can cause liver damage, which is believed to involve glutathione depletion.⁵ In one study involving rats, silymarin protected against acetaminophen-induced glutathione depletion.⁶ While studies to confirm this action in humans have not been conducted, some doctors recommend silymarin supplementation with 200 mg milk thistle extract, containing 70–80% silymarin, three times per day for people taking acetaminophen in large amounts for more than one year and/or with other risk factors for liver problems.

Schisandra (Schisandra chinensis)
Gomisin A is a constituent found in the Chinese herb schisandra. In a study of rats given liver-damaging amounts of acetaminophen, gomisin A appeared to protect against some liver damage but did not prevent glutathione depletion⁷ (unlike milk thistle, as reported above). Studies have not yet confirmed this action in humans.

Interactions with Foods and Other Compounds

Food
Food, especially foods high in pectin (including jellies), carbohydrates, and large amounts of cruciferous vegetables (broccoli, Brussels sprouts, cabbage, and others) can interfere with acetaminophen absorption.⁸ It is unclear how much effect this interaction has on acetaminophen activity.

Alcohol
Moderate to high amounts of acetaminophen have caused liver damage in people with alcoholism.⁹ To prevent problems, people taking acetaminophen should avoid alcohol.

1. Vale JA, Proudfoot AT. Paracetamol (acetaminophen) poisoning. Lancet 1995;346:547–52.

2. Perry HE, Shannon MW. J Pediatr 1998;132:149–52.

3. Houston JB, Levy G. Drug biotransformation interactions in man. VI: Acetaminophen and ascorbic acid. J Pharm Sci 1976;65:1218–21.

4. Valenzuela A, Aspillaga M, Vial S, Guerra R. Selectivity of silymarin on the increase of the glutathione content in different tissues of the rat. Planta Med 1989;55:420–2.

5. Threlkeld DS, ed. Central Nervous System Drugs, Acetaminophen. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Mar 1997, 247–f.

6. Campos R, Garrido A, Guerra R, Valenzuela A. Silybin dihemisuccinate protects against glutathione depletion and lipid peroxidation induced by acetaminophen on rat liver. Planta Med 1989;55:417–9.

7. Yamada S, Murawaki Y, Kawasaki H. Preventive effect of gomisin A, a lignan component of schizandra fruits, on acetaminophen-induced hepatotoxicity in rats. Biochem Pharmacol 1993;46:1081–5.

8. Holt GA. Food & Drug Interactions. Chicago: Precept Press, 1998, 2.

9. Threlkeld DS, ed. Central Nervous System Drugs, Acetaminophen. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Mar 1997, 247–f.

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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over-the-counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires December 2003.

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