Numbers needed to treat of two to three compare well with the most effective analgesics in acute pain, and with anticonvulsants in neuropathic pain. The estimated number needed to treat from one study of pain after pain was 1.7. This range is lower than traditional doses for depression of 150-300 mg. About one in 30 patients has to stop taking the drug because of intolerable or unmanageable side effects. The profile of adverse effects is the same as when the drugs are used to treat depression.
Antidepressants have two roles in managing chronic pain.
There used to be a dogma that the character of the neuropathic pain was predictive of response, so that burning pain should be treated with antidepressants and shooting pain with anticonvulsants. This can be particularly effective in cancer who have pain at multiple pain sites, some nociceptive and some neuropathic. Improved sleep is a huge bonus. Tricyclics have proved efficacy in chronic pain, but there is little evidence that one drug is better than another, though some patients troubled by adverse effects may benefit from changing drug. We advise patients to increase the dose by 25 mg at weekly intervals until they either achieve pain relief or adverse effects become problematic.