From: Use of a fixed combination of acetylsalicylic acid, acetaminophen and caffeine compared with acetaminophen alone in episodic tension-type headache: meta-analysis of four randomized, double-blind, placebo-controlled, crossover studies
Adverse event
Number of patients, n (%)
AAC (n = 1400)
APAP (n = 1400)
Placebo (n = 702)
Any adverse event
241 (17)
136 (10)
61 (9)
Stomach upset
130 (9)
67 (5)
34 (5)
Nervousness
61 (4)
13 (1)
4 (1)
Dizziness
58 (4)
22 (2)
7 (1)