Acetaminophen / diphenhydramine / phenylephrine Side Effects
For the Consumer
Applies to acetaminophen / diphenhydramine / phenylephrine: oral liquid, oral packet, oral suspension, oral tablet
What are some side effects that I need to call my doctor about right away?
WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:
- Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
- Signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
- Not able to pass urine or change in how much urine is passed.
- A very bad skin reaction (Stevens-Johnson syndrome/toxic epidermal necrolysis) may happen. It can cause very bad health problems that may not go away, and sometimes death. Get medical help right away if you have signs like red, swollen, blistered, or peeling skin (with or without fever); red or irritated eyes; or sores in your mouth, throat, nose, or eyes.
What are some other side effects of this drug?
All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:
- Feeling nervous and excitable.
- Not able to sleep.
- Feeling sleepy.
These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.
You may report side effects to the FDA at 1-800-FDA-1088. You may also report side effects at http://www.fda.gov/medwatch.
For Healthcare Professionals
Two cases hypotension have been reported following the administration of acetaminophen. Both patients experienced significant decreases in blood pressure. One of the two patients required pressor agents to maintain adequate mean arterial pressures. Neither episode was associated with symptoms of anaphylaxis. Neither patient was rechallenged after resolution of the initial episode.[Ref]
Dermatologic side effects have included erythematous skin rashes. Acetaminophen associated bullous erythema and purpura fulminans have also been reported. Acetaminophen has been associated with a risk of rare but potentially fatal serious skin reactions known as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and acute generalized exanthematous pustulosis (AGEP).[Ref]
One study has suggested that acetaminophen may precipitate acute biliary pain and cholestasis. The mechanism of this effect may be related to inhibition of prostaglandin and alterations in the regulation of the sphincter of Oddi.[Ref]
Gastrointestinal side effects of acetaminophen have included rare cases of acute pancreatitis.
Hematologic side effects of acetaminophen have included rare cases of thrombocytopenia. Methemoglobinemia with resulting cyanosis has also been observed in the setting of acute overdose.
Alcoholic patients may develop hepatotoxicity after even modest doses of acetaminophen. In healthy patients, approximately 15 grams of acetaminophen is necessary to deplete liver glutathione stores by 70% in a 70 kg person. However, hepatotoxicity has been reported following smaller doses. Glutathione concentrations may be repleted by the antidote N-acetylcysteine. One case report has suggested that hypothermia may also be beneficial in decreasing liver damage during overdose.
In a recent retrospective study of 306 patients admitted for acetaminophen overdose, 6.9% had severe liver injury but all recovered. None of the 306 patients died.
Hepatic side effects of acetaminophen have included severe and sometimes fatal dose dependent hepatitis in alcoholic patients. Hepatotoxicity has been increased during fasting. Several cases of hepatotoxicity from chronic acetaminophen therapy at therapeutic doses have also been reported despite a lack of risk factors for toxicity.[Ref]
Most commonly, hypersensitivity to diphenhydramine has manifested itself in patients receiving systemic drug after being sensitized to it by topical application. Sensitization with systemic administration has also been reported.[Ref]
Hypersensitivity side effects of acetaminophen have included rare reports of anaphylaxis and fixed drug eruptions.
The CNS depressant effect of diphenhydramine parallels its plasma concentrations. The plasma concentration threshold for sedation is 30 to 42 ng/mL, and to cause mental impairment is 58 to 74 ng/mL. Patients should be warned against driving while taking diphenhydramine.
Dystonic reactions have been accompanied by dizziness, mental confusion, rigidity, lip and tongue protrusion, trismus, torticollis, and swallowing difficulties and generally resolve spontaneously. Toxic encephalopathy has been reported in a child with chicken pox treated generously with topical diphenhydramine.
Nervous system side effects of diphenhydramine have included depression with drowsiness and sedation in nearly all patients treated. Motor skills may be impaired. Dystonic reactions have been reported after single doses of diphenhydramine.
Renal side effects of acetaminophen have included acute tubular necrosis and interstitial nephritis. Adverse renal effects are most often observed after overdose, after chronic abuse (often with multiple analgesics), or in association with acetaminophen-related hepatotoxicity.[Ref]
Acute tubular necrosis usually occurs in conjunction with liver failure, but has been observed as an isolated finding in rare cases. A possible increase in the risk of renal cell carcinoma has been associated with chronic acetaminophen use as well.
A recent case control study of patients with end-stage renal disease suggested that long term consumption of acetaminophen may significantly increase the risk of end-stage renal disease particularly in patients taking more than two pills per day.[Ref]
Respiratory side effects of acetaminophen have included a case of eosinophilic pneumonia.
Respiratory side effects of phenylephrine have included respiratory difficulty.[Ref]
General side effects of phenylephrine have included pallor and weakness.[Ref]
1. "Product Information. Sudafed PE Severe Cold (APAP/diphenhydramine/phenylephrine)." Pfizer U.S. Pharmaceuticals Group, New York, NY.
2. "Product Information. Tylenol Extra Strength PM (acetaminophen-diphenhydramine)." Johnson and Johnson/Merck Consumer, Fort Washington, PA.
3. Brown G "Acetaminophen-induced hypotension." Heart Lung 25 (1996): 137-40
4. "Product Information. Ah-Chew D (phenylephrine)." WE Pharmaceuticals Inc, Ramona, CA.
5. Halevi A, BenAmitai D, Garty BZ "Toxic epidermal necrolysis associated with acetaminophen ingestion." Ann Pharmacother 34 (2000): 32-4
6. Lee WM "Medical progress: drug-induced hepatotoxicity." N Engl J Med 333 (1995): 1118-27
7. Gursoy M, Haznedaroglu IC, Celik I, Sayinalp N, Ozcebe OI, Dundar SV "Agranulocytosis, plasmacytosis, and thrombocytosis followed by a leukemoid reaction due to acute acetaminophen toxicity." Ann Pharmacother 30 (1996): 762-5
8. Barranco P, LopezSerrano MC, MorenoAncillo A "Anaphylactic reaction due to diphenhydramine." Allergy 53 (1998): 814
9. Kawada A, Hiruma M, Noguchi H, Ishibashi A "Fixed drug eruption induced by acetaminophen in a 12-year-old girl." Int J Dermatol 35 (1996): 148-9
10. Richardson GS, Roehrs TA, Rosenthal L, Koshorek G, Roth T "Tolerance to daytime sedative effects of h1 antihistamines." J Clin Psychopharmacol 22 (2002): 511-5
11. Sexton JD, Pronchik DJ "Diphenhydramine induced psychosis with therapeutic doses." Am J Emerg Med 15 (1997): 548-9
12. Eguia L, Materson BJ "Acetaminophen-related acute renal failure without fulminant liver failure." Pharmacotherapy 17 (1997): 363-70
Some side effects may not be reported. You may report them to the FDA.
More about acetaminophen/diphenhydramine/phenylephrine
- During Pregnancy
- Dosage Information
- Drug Images
- Drug Interactions
- 4 Reviews
- Drug class: upper respiratory combinations
- FDA Alerts (2)
- Acetaminophen, diphenhydramine, and phenylephrine
- Acetaminophen, Diphenhydramine, and Phenylephrine Pods
- Acetaminophen, Diphenhydramine, and Phenylephrine Powder Packet
- Acetaminophen, Diphenhydramine, and Phenylephrine Tablets
- Acetaminophen, Diphenhydramine, and Phenylephrine Liquid
- Acetaminophen, Diphenhydramine, and Phenylephrine Suspension