Drug
Diphenhydramine-Acetaminophen
Drug Interactions
See also Warning section.
Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval.
Some products that may interact with this drug are: antihistamines applied to the skin (such as diphenhydramine cream, ointment, spray), ketoconazole, levoketoconazole.
Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or other antihistamines (such as cetirizine, diphenhydramine).
Antihistamines are ingredients found in many nonprescription products and in some combination prescription medications. Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may also contain an antihistamine or other ingredients that cause drowsiness. Ask your pharmacist about using those products safely.
This medication may interfere with certain medical/lab tests (such as urine 5-HIAA, allergy skin tests), possibly causing false test results. Make sure lab personnel and all your doctors know you use this drug.
Negative Interactions
4- Potential Negative Interaction
Chlorpheniramine
Henbane
Antihistamines, including chlorpheniramine, can cause “anticholinergic” side effects such as dryness of mouth and heart palpitations. Henbane (Hyoscyamus niger) also has anticholinergic activity and side effects. Therefore, use of henbane with chlorpheniramine could increase the risk of anticholinergic side effects, though apparently no interactions have yet been reported. Henbane should not be taken except by prescription from a physician trained in its use, as it is extremely toxic.
HenbaneChlorpheniramine- Blumenthal M, ed. The Complete German Commission E Monographs. Austin, TX: American Botanical Council, 1998, 146.
- Potential Negative Interaction
Acetaminophen
N-Acetyl Cysteine
Hospitals use oral and intravenous NAC to treat liver damage induced by acetaminophen overdose poisoning. 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. However, acetaminophen toxicity is a potential medical emergency, and should only be managed by qualified healthcare professionals.
N-Acetyl CysteineAcetaminophen- Vale JA, Proudfoot AT. Paracetamol (acetaminophen) poisoning. Lancet 1995;346:547-52.
- Perry HE, Shannon MW. J Pediatr 1998;132:149-52.
- Reduces Effectiveness
Acetaminophen
Cruciferous Vegetables
Food, especially foods high in pectin (including jellies), carbohydrates, and many types of cruciferous vegetables (broccoli, Brussels sprouts, cabbage, and others) can interfere with acetaminophen absorption. It is unclear how much effect this interaction has on acetaminophen activity.
Cruciferous VegetablesAcetaminophen- Holt GA. Food & Drug Interactions. Chicago: Precept Press, 1998, 2.
- Reduces Effectiveness
Acetaminophen
Hibiscus
One small study found that hibiscus could decrease levels of acetaminophen if the drug was taken after the tea was consumed though it was not entirely clear if the decreases were clinically significant.
HibiscusAcetaminophen- 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.
Supportive Interactions
1- Reduce Side Effects
Acetaminophen
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. Acetaminophen can cause liver damage, which is believed to involve glutathione depletion. In one study involving rats, silymarin protected against acetaminophen-induced glutathione depletion. 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.
Milk ThistleAcetaminophen- 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.
- Threlkeld DS, ed. Central Nervous System Drugs, Acetaminophen. In Facts and Comparisons Drug Information. St. Louis, MO: Facts and Comparisons, Mar 1997, 247-f.
- 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.
Explanation Required
2- Needs Explanation
Acetaminophen
Schisandra
Gomisin A is a constituent found in the Chinese herb schisandra (Schisandra chinensis). 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 depletion (unlike milk thistle, as reported above). Studies have not yet confirmed this action in humans.
SchisandraAcetaminophen- 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.
- Needs Explanation
Acetaminophen
Vitamin C
Taking 3 grams vitamin C with acetaminophen has been shown to prolong the amount of time acetaminophen stays in the body. 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. However, increasing the time acetaminophen is in the body might also theoretically increase its toxicity. Consult with a doctor before taking vitamin C along with acetaminophen.
Vitamin CAcetaminophen- Houston JB, Levy G. Drug biotransformation interactions in man. VI: Acetaminophen and ascorbic acid. J Pharm Sci 1976;65:1218-21.
- FDA Information on Acetaminophen, Jan 13, 2011. http://www.fda.gov/Drugs/DrugSafety/InformationbyDrugClass/ucm165107.htm