David Lloyd

Summary of Interactions with Vitamins, Herbs, and Foods
In some cases, an herb or supplement may appear in more than one category, which may seem contradictory. For clarification, read the full article for details about the summarized interactions.

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.	Milk thistle* NAC
May be Beneficial: Supportive interaction—Taking these supplements may support or otherwise help your medication work better.	Vitamin C*
Avoid: Reduced drug absorption/bioavailability—Avoid these supplements when taking this medication since the supplement may decrease the absorption and/or activity of the medication in the body.	Hibiscus
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
Adverse interaction	None known

An asterisk (*) next to an item in the summary indicates that the interaction is supported only by weak, fragmentary, and/or contradictory scientific evidence.

Interactions with Dietary Supplements

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

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

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

Interactions with Herbs

Hibiscus
One small study found that hibiscus could decrease levels of paracetamol if the drug was taken after the tea was consumed though it was not entirely clear if the decreases were clinically significant.⁴

Milk thistle
Silymarin is a collection of complex flavonoids found in milk thistle (Silybum marianum) that has been shown to elevate liver glutathione levels in rats.⁵ Paracetamol can cause liver damage, which is believed to involve glutathione depletion.⁶ In one study involving rats, silymarin protected against paracetamol-induced glutathione depletion.⁷ 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 paracetamol in large amounts for more than one year and/or with other risk factors for liver problems.

Schisandra
Gomisin A is a constituent found in the Chinese herb schisandra (Schisandra chinensis). In a study of rats given liver-damaging amounts of paracetamol, gomisin A appeared to protect against some liver damage but did not prevent glutathione depletion⁸ (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, Brussel sprouts, cabbage, and others) can interfere with paracetamol absorption.⁹ It is unclear how much effect this interaction has on paracetamol activity.

Alcohol
Moderate to high amounts of paracetamol have caused liver damage in people with alcoholism.¹⁰ To prevent problems, people taking paracetamol should avoid alcohol.

References

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. Kolawole JA, Maduenyi A. Effect of zobo drink (Hibiscus sabdariffa water extract) on the pharmacokinetics of acetaminophen in human volunteers. Eur J Drug Metab Pharmacokinet 2004;29:25–9.

5. 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.

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

7. 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.

8. 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.

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

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