Tylenol (acetaminophen) side effects list for healthcare professionals

The following serious adverse reactions are discussed elsewhere in the labeling:

  • Hepatic Injury
  • Serious Skin Reactions
  • Allergy and Hypersensitivity

Clinical Trial Experience

Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed cannot be directly compared to rates in other clinical trials and may not reflect the rates observed in practice.

Adult Population

A total of 1,020 adult patients have received acetaminophen in clinical trials, including 37.3% (n=380) who received 5 or more doses, and 17% (n=173) who received more than 10 doses. Most patients were treated with acetaminophen 1,000 mg every 6 hours. A total of 13.1% (n=134) received acetaminophen 650 mg every 4 hours.

All adverse reactions that occurred in adult patients treated with either acetaminophen or placebo in repeated dose, placebo-controlled clinical trials at an incidence = 3% and at a greater frequency than placebo are listed in Table 3. The most common adverse events in adult patients treated with acetaminophen (incidence = 5% and greater than placebo) were nausea, vomiting, headache, and insomnia.

Table 3. Treatment-Emergent Adverse Reactions Occurring = 3% in Acetaminophentreated Patients and at a greater frequency than Placebo in Placebo-Controlled, Repeated Dose Studies
System Organ Class – Preferred Term Acetaminophen
(N=402)
n (%)
Placebo
(N=379)
n (%)
Gastrointestinal Disorders
Nausea
Vomiting
138 (34)
62 (15)
119 (31)
42 (11)
General Disorders and Administration Site Conditions Pyrexia* 22 (5) 52 (14)
Nervous System Disorders
Headache
39 (10) 33 (9)
Psychiatric Disorders
Insomnia
30 (7) 21 (5)
* Pyrexia adverse reaction frequency data is included in order to alert healthcare practitioners that the antipyretic effects of acetaminophen may mask fever.

Other Adverse Reactions Observed During Clinical Studies of Acetaminophen in Adults

The following additional treatment-emergent adverse reactions were reported by adult subjects treated with acetaminophen in all clinical trials (n=1,020) that occurred with an incidence of at least 1% and at a frequency greater than placebo (n=525).

Blood and lymphatic system disorders: anemia

General disorders and administration site conditions: fatigue, infusion site pain, edema peripheral

Investigations: aspartate aminotransferase increased, breath sounds abnormal

Metabolism and nutrition disorders: hypokalemia

Musculoskeletal and connective tissue disorders: muscle spasms, trismus

Psychiatric disorders: anxiety

Respiratory, thoracic and mediastinal disorders: dyspnea

Vascular disorders: hypertension, hypotension

Pediatric Population

A total of 355 pediatric patients (47 neonates, 64 infants, 171 children, and 73 adolescents) have received acetaminophen in active-controlled (n=250) and open-label clinical trials (n=225), including 59.7% (n=212) who received 5 or more doses and 43.1% (n=153) who received more than 10 doses. Pediatric patients received acetaminophen doses up to 15 mg/kg on an every 4 hours, every 6 hours, or every 8 hours schedule. The maximum exposure was 7.7, 6.4, 6.8, and 7.1 days in neonates, infants, children, and adolescents, respectively.

The most common adverse events (incidence = 5%) in pediatric patients treated with acetaminophen were nausea, vomiting, constipation, pruritus, agitation, and atelectasis.

Other Adverse Reactions Observed During Clinical Studies of Acetaminophen in Pediatrics

The following additional treatment-emergent adverse reactions were reported by pediatric subjects treated with acetaminophen (n=355) that occurred with an incidence of at least 1%.

Blood and lymphatic system disorders: anemia

Cardiac disorders: tachycardia

Gastrointestinal disorders: abdominal pain, diarrhea

General disorders and administration site conditions: injection site pain, edema peripheral, pyrexia

Investigations: hepatic enzyme increase

Metabolism and nutrition disorders: hypoalbuminemia, hypokalemia, hypomagnesemia, hypophosphatemia, hypervolemia

Musculoskeletal and connective tissue disorders: muscle spasm, pain in extremity

Nervous system disorders: headache

Psychiatric disorders: insomnia

Renal and urinary disorders: oliguria

Respiratory, thoracic and mediastinal disorders: pulmonary edema, hypoxia, pleural effusion, stridor, wheezing

Skin and subcutaneous tissue disorders: periorbital edema, rash

Vascular disorders: hypertension, hypotension