Diclofenac

Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID). It relieves pain, reduces inflammation, and lowers fever.

The active ingredient is available in numerous dosage forms: tablets, extended-release capsules, gel, patches, and suppositories. Well-known brands include Voltaren® Resinat, Voltaren Emulgel, and Arthotec® (combination with misoprostol for stomach protection).

Diclofenac is used for acute and chronic pain, particularly for joint problems, back pain, sports injuries, and rheumatic diseases.

Diclofenac inhibits the enzyme cyclooxygenase (COX-1 and COX-2):

Mechanism of action:

• Blocks the formation of prostaglandins
• Prostaglandins are messenger substances that mediate pain, inflammation, and fever
• This inhibition weakens pain signals and reduces inflammation

Triple action:

• Analgesic: pain relief
• Anti-inflammatory: inhibition of inflammation
• Antipyretic: fever reduction

Topical use (gel): When applied as a gel, diclofenac reaches the underlying tissue directly. Systemic exposure is considerably lower than with tablets.

Diclofenac is suitable for:

• Acute and chronic joint pain
• Back pain and intervertebral disc problems
• Rheumatoid arthritis and osteoarthritis
• Sports injuries (bruises, strains, sprains)
• Menstrual pain
• Postoperative pain
• Gout attacks

Topical (gel), especially for:

• Localized muscle and joint pain
• Sports injuries
• Osteoarthritis of the small joints

Not suitable:

• In case of stomach ulcers or gastrointestinal bleeding
• In case of heart failure (NYHA II–IV), ischemic heart disease, peripheral arterial disease or cerebrovascular disease
• In case of severe liver or kidney failure
• In the last trimester of pregnancy

Tablets / extended-release capsules:

• 25 mg, 50 mg, 75 mg
• Extended-release form: 75 mg, 100 mg

Gel (topical):

• 1% or 2% gel (e.g., Voltaren Emulgel)

Suppositories:

• 50 mg, 100 mg

Combination product Arthotec®:

• Diclofenac 50 mg / 75 mg + misoprostol 200 µg

Usual daily oral dose:

• 50–150 mg, divided into 2–3 single doses
• Lowest effective dose for the shortest necessary time

Tablets:

• Take with a glass of water
• Preferably with or after a meal
• Do not chew or break the tablets (extended-release forms)

Gel:

• Apply 2–4 g (approx. the size of a cherry to a walnut) to the affected area
• Massage in gently, then wash your hands
• 3–4 times daily, not on open wounds

General notes:

• Use for as short a time as possible and at the lowest effective dose
• For stomach problems: proton pump inhibitor (PPI) for stomach protection
• Do not take together with other NSAIDs

Diclofenac must not be taken in cases of:

• Known hypersensitivity to diclofenac or other NSAIDs
• Active gastrointestinal ulcers or bleeding
• Known heart failure (NYHA II–IV), ischemic heart disease, peripheral arterial disease or cerebrovascular disease
• Severe liver or kidney failure
• Last trimester of pregnancy
• History of coronary artery bypass surgery

Caution in cases of:

• Cardiovascular risk factors (high blood pressure, diabetes, smoking)
• Older patients
• Asthma (aspirin intolerance syndrome possible)
• Concomitant use of blood thinners

Pregnancy/breastfeeding: In the 1st and 2nd trimesters only if strictly indicated. Contraindicated in the 3rd trimester. During breastfeeding, short-term use at a low dose is possible.

Common (1–10%):

• Stomach pain, nausea, diarrhea
• Headache, dizziness
• Elevated liver enzymes
• Gastrointestinal ulcers (possibly with bleeding and perforation)

Uncommon (0.1–1%):

• Vomiting blood, black tarry stools or bloody diarrhea
• Skin rash, itching
• Edema (fluid retention)

Rare but serious:

• Cardiovascular events (heart attack, stroke) with long-term use
• Severe skin reactions
• Kidney function disorders
• Liver damage

Topical (gel): Significantly fewer systemic side effects. Locally: skin irritation, redness, itching.

Increased risk of bleeding with:

• Anticoagulants (Marcumar, DOACs)
• Aspirin, other NSAIDs
• SSRI antidepressants
• Corticosteroids

Reduced effect of:

• Blood pressure medications (ACE inhibitors, sartans, diuretics)

Increased toxicity of:

• Methotrexate
• Lithium
• Digoxin
• Cyclosporine

Kidney damage intensified with:

• ACE inhibitors + diuretics (triple whammy)