Diclofenac Gel Effects and Side Effects

Products

Diclofenac gels have been on the market in many countries since 1985. In addition to the original Voltaren, numerous products and generics are available today. The usual concentration is 1%. In 2012, an additional 2% gel was launched (Voltaren Dolo forte Emulgel). Generics were approved in 2020. Since 2011, a gel containing 3% diclofenac has been commercially available in many countries for the treatment of actinic keratoses (Solaraze). See under diclofenac gel 3%.

Structure and properties

Diclofenac (C14H11Cl2NO2, Mr = 296.15 g/mol) is often present in gels as the sodium salt, a white to slightly yellowish crystalline powder that is sparingly soluble in water. In some gels, it is also present as diethylamine (e.g., Voltaren), epolamine (e.g., Flector), or potassium salt. There may be differences between the various preparations and salts in terms of absorption and distribution to tissues (see literature). It cannot be ruled out that a patient may react differently to two different products.

Effects

Diclofenac (ATC M02AA15) is analgesic, anti-inflammatory, and cooling when applied locally because of its aqueous-alcoholic gel base. It penetrates tissues and inhibits prostaglandin synthesis by inhibiting cyclooxygenase. Topical diclofenac appears to be slightly less effective than oral diclofenac taken as a tablet or capsule, but is better tolerated. Oral diclofenac can cause numerous adverse effects, including severe ones.

Indications

For the external treatment of pain, inflammation, and swelling associated with sports and accidental injuries such as sprains, contusions, and strains; soft tissue rheumatism; and rheumatic diseases such as osteoarthritis. Diclofenac 3% is used to treat actinic keratoses.

Dosage

According to the package insert. The instructions should be followed and the gel should not be applied in an overdose.

Contraindications

Diclofenac gel should not be used in cases of hypersensitivity (including to other NSAIDs such as acetylsalicylic acid or ibuprofen), in children <12 years of age, during pregnancy and lactation. It should not be applied to injured or diseased skin areas and should not come into contact with the eyes or mucous membranes. For complete precautions, see the drug label.

Interactions

Drug-drug interactions are not known. The risk for systemic interactions is considered low. However, they cannot be completely ruled out with large-area and long-term use.

Adverse effects

The risk for systemic adverse effects of diclofenac is considered low when used correctly. Possible adverse effects include local skin reactions such as eczema, skin redness, allergic contact dermatitis, bullous dermatitis, photosensitization, pustular rash, and hypersensitivity reactions and asthma.