Nefopam (Acupan) is a centrally-acting but non-opioid analgesic drug of the benzoxazocine chemical class which was developed by Riker Laboratories in the 1960s. It is widely used, mainly in European countries, for the relief of moderate to severe pain as an alternative to opioid analgesic drugs. Animal studies have shown that nefopam has a potentiating (analgesic-sparing) effect on morphine and other opioids by broadening the antinociceptive action of the opioid and possibly other mechanisms, generally lowering the dose requirements of both when they are used concomitantly.

Nefopam has additional action in the prevention of shivering, which may be a side effect of other drugs used in surgery.

Nefopam at a dose of 30–120 mg is significantly more effective than aspirin as an analgesic, although with a greater incidence of side effects such as sweating, dizziness and nausea, especially at higher doses.

Nefopam is around half the potency and slightly less effective as an analgesic compared to morphine, or oxycodone, but tends to produce fewer side effects, does not produce respiratory depression, and has much less abuse potential, and so is useful either as an alternative to opioids, or as an adjunctive treatment for use alongside opioid(s) or other analgesics.