The Ministry of Health says all Paradex tablets and Capadex capsules will be withdrawn from the market because the risks outweigh the possible benefits.
The medicines are analgesics used to treat chronic moderate pain.
It says a review has shown the drugs are no better at treating pain than paracetamol.
It says they could cause extra side effects to those caused by paracetamol, and are dangerous in overdose or if taken with alcohol.
The ministry says the medicines will be withdrawn gradually, to enable patients to transfer to other treatments.
It says any patient taking Paradex or Capadex should keep taking them and see their doctor when they need a new prescription.