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 17.0% (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 4. The most common adverse events in adult patients treated with acetaminophen (incidence ≥ 5% and greater than placebo) were nausea, vomiting, headache, and insomnia.
Table 4. Treatment-Emergent Adverse Reactions Occurring in ≥ 3% of Acetaminophen-treated Adult Patients and at a Greater Frequency than Placebo in Placebo-Controlled, Repeated Dose Studies | * Pyrexia adverse reaction frequency data is included in order to alert healthcare practitioners that the antipyretic effects of acetaminophen may mask fever. |
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)
|
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 483 pediatric patients (72 neonates, 167 infants, 171 children, and 73 adolescents) have received acetaminophen in active-controlled (n=250) and open-label clinical trials (n=225), including 43.9% (n=212) who received 5 or more doses and 31.2% (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, and pruritus.
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=483) that occurred with an incidence of at least 1%.
Blood and lymphatic system disorders: anemia
Gastrointestinal disorders: diarrhea
General disorders and administration site conditions: pyrexia, injection site pain
Metabolism and nutrition disorders: hypokalemia, hypomagnesemia, hypoalbuminemia, hypophosphatemia
Musculoskeletal and connective tissue disorders: muscle spasm
Nervous system disorders: headache
Psychiatric disorders: agitation
Renal and urinary disorders: oliguria
Respiratory, thoracic and mediastinal disorders: atelectasis, pleural effusion, pulmonary edema, stridor, wheezing
Vascular disorders: hypotension, hypertension