Relafen is the brand name for the generic drug Nabumetone and it is manufactured by GlaxoSmithKline. It is an NSAID or a non-steroidal anti-inflammatory drug and it is available in tablets of 500 and 750 mg.
Relafen is used to treat:

Action
This medication works on the enzymes that are the ones that produce prostaglandins in the body. When the prostaglandin production is reduced or stopped, it means the inflammation is reduced and this results in a decrease in the swelling, the pain and the fever. This drug is used to treat mild to moderate pain in arthritis and while it might take a while for the results to show, the medication is usually very effective in pain management.
Side Effects
This drug can have side effects and while most users do not experience side effects from most NSAIDs, there can be some who experience side effects that range from mild to moderate to serious. There could be pain in the stomach, diarrhea or constipation, cramps, nausea, skin rash and itching, sore throat, breathing difficulties and allergies like hives. There could be dark colored stools and this could be due to internal bleeding, dizziness, kidney and liver complaints, ringing in the ears and maybe even loss of hearing.
Caution
Before you are prescribed this medication, you need to tell your doctor about all the medication you are on as well as any ailments that you are suffering from, so there is no drug interaction or any worsening of current symptoms. You also need to tell him if you are allergic to any drugs including aspirin. You need to be cautious about smoking and drinking alcohol when you are on this medication as it could make you very drowsy. Older people need to be monitored when given this drug. As this drug could cause internal bleeding, you must keep a watch and report anything out of the ordinary to your doctor. Anyone who is prone to ulcers could have serious side effects with stomach and intestinal bleeding.
This medication is contraindicated in nursing mothers and should ideally be avoided by pregnant women as well. It should not be used for the pain after a bypass procedure. Patients with heart, liver and kidney problems should also try and avoid its use.
