What is diclofenac

DiclofenacDrug groupsNSARDiclofenac is an active ingredient from the group of non-steroidal anti-inflammatory drugs with analgesic, antipyretic and anti-inflammatory properties. The effects are based on the inhibition of cyclooxygenase and thus the reduced prostaglandin synthesis. Diclofenac is used for the treatment of pain and inflammation from various causes. The oral drugs are administered before or with meals, depending on the dosage form. The most common possible adverse effects include indigestion, water retention, high blood pressure, rash, headache, dizziness, and drowsiness. As with all NSAIDs, serious side effects can occur, especially with long-term and high-dose treatment.

synonymous: diclofenacum


Diclofenac is available in the form of tablets, capsules, soft capsules (liquid caps), dragees, drops, suppositories, as an injection solution, gel, plaster and eye drops (Voltaren®, generics). The pain reliever has been approved in Switzerland since 1974. This article relates to oral use.

Also see the following articles for more information: Diclofenac Gels, Diclofenac Gel 3%, Diclofenac Injection and Diclofenac Eye Drops.

Structure and properties

Diclofenac (C.14H11Cl2NO2, Mr = 296.15 g / mol) is present in the medicinal products for ingestion either as diclofenac sodium or diclofenac potassium. They are white to slightly yellowish, crystalline and slightly hygroscopic powders that are sparingly soluble in water. Diclofenac is one of the arylacetic acid resp. the phenylacetic acid derivatives.


Diclofenac (ATC M01AB05) has analgesic, antipyretic and anti-inflammatory properties. The effects are based on the inhibition of the enzyme cyclooxygenase and the reduced formation of prostaglandins. Diclofenac has a short half-life of one to three hours and is therefore also administered in retarded dosage forms.

Mechanism of action of NSAIDs, click to enlarge. Illustration © PharmaWiki


For the treatment of pain and inflammation of various causes, for example arthritis, osteoarthritis, after operations and injuries, menstrual cramps, migraines and gout. According to the specialist information, fever alone is not an indication.


According to the specialist information. The usual maximum daily dose for adults is 100 to 150 mg. In self-medication, a maximum of 75 mg (25 mg 3 times a day) may be administered daily. Depending on the dosage form, the drugs are taken before or with meals. If taken with meals, tolerability may be increased, but the effects will be less rapid.


The complete precautionary measures can be found in the medicinal product information sheet.


Diclofenac is metabolized by CYP2C9. For the extensive information on drug interactions, we refer to the specialist information.

unwanted effects

The most common possible adverse effects include indigestion (such as nausea, vomiting, diarrhea, abdominal pain, gas), fluid retention and water retention, high blood pressure, rash, headache, dizziness, and drowsiness. As with all non-steroidal anti-inflammatory drugs, long-term treatment can cause severe side effects such as gastrointestinal ulcers, liver dysfunction, and kidney failure.

see also

NSAIDs, diclofenac gel, diclofenac gel 3%, diclofenac eye drops, diclofenac injection, stomach protection

  • Medicinal product information (CH)
  • European Pharmacopoeia PhEur
  • Gan T.J. Diclofenac: an update on its mechanism of action and safety profile. Curr Med Res Opin, 2010, 26 (7), 1715-31 Pubmed
  • McNeely W., Goa K.L. Diclofenac-potassium in migraine: a review. Drugs, 1999, 57 (6), 991-1003 Pubmed
  • Pavelka K. A comparison of the therapeutic efficacy of diclofenac in osteoarthritis: a systematic review of randomized controlled trials. Curr Med Res Opin, 2012, 28 (1), 163-78 Pubmed
  • Todd P.A., Sorkin E.M. Diclofenac sodium. A reappraisal of its pharmacodynamic and pharmacokinetic properties, and therapeutic efficacy. Drugs, 1988, 35 (3), 244-85 Pubmed

Conflicts of Interest: None / Independent. The author has no relationships with the manufacturers and is not involved in the sale of the products mentioned.

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This article was last changed on 3/11/2021.
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