Caffeine effective as an analgesic adjuvant

Clinical question: 
How effective is caffeine as an analgesic adjuvant for acute pain in adults?
Bottom line: 
Adding caffeine (at a dose equivalent to a mug of coffee, ie, about 100mg) to a standard dose of common analgesics, such as paracetamol or ibuprofen, increased the number of people with acute pain who experience a good level of pain relief (at least 50% of the maximum) by 5 to 10% (NNT* 15). The most common conditions studied were postoperative dental pain, postpartum pain, menstrual period pain and headache. One serious adverse event was reported with caffeine but was considered unrelated to any study medication. *NNT = number needed to treat to benefit 1 individual.
Caveat: 
Most comparisons individually demonstrated numerical superiority with caffeine but not statistical superiority.
Context: 
Caffeine is commonly used as a component in analgesics available from pharmacies without a prescription in the belief that it enhances analgesic efficacy.
Review CD#: 
CD009281
PEARLS No: 
362
Date: 
July, 2012
Authored by: 
Brian R McAvoy