Diclofenac: Uses, Dosage, Side Effects, Warnings & Interactions

Topical gel & solutions

• Voltaren 1% gel (OTC)Dosed using the included card. Upper extremities: 2 g per affected joint QID (max 8 g/dayper joint). Lower extremities: 4 g per affected joint QID (max 16 g/day per joint). Total maximum across all joints: 32 g/day. Avoid bathing for 1 hour after application.
• Pennsaid topical solution: 1.5%, 40 drops to each affected knee four times a day; 2%, two pumps to each knee twice daily.

Transdermal patch (epolamine)

Flector (diclofenac epolamine 1.3%) delivers diclofenac through the skin to the painful area (e.g., strains/sprains). Follow the specific label for application site and frequency (commonly twice daily). (Consult current labeling for your market.)

Ophthalmic solution

Ophthalmic diclofenac (0.1%) reduces post‑cataract surgery pain and photophobia; dosing is by prescription under the eye surgeon’s guidance.

Voltaren 1% gel: exact dosing card amounts & daily limits

• Hands, wrists, elbowsapply 2 g to each affected joint QID; ≤8 g/day per joint.
• Knees, ankles, feetapply 4 g to each affected joint QID; ≤16 g/day per joint.
• Do not exceed 32 g/day total across all joints. Rub in gently; avoid bathing for ≥1 hour; wash hands unless hands are the treated area.

Topical solutions (Pennsaid)

• 1.5% solution40 drops to each affected knee four times daily.
• 2% solution2 pumps (40 mg) to each affected knee twice daily.

Flector patch: placement & schedule

Apply to the most painful area on clean, dry skin; replace every 12 hours (common pattern). Do not use with heat pads. (Confirm the exact schedule on your country’s label.)

Ophthalmic dosing

Your surgeon will provide a specific drop schedule around cataract or corneal refractive surgery. Do not touch the dropper tip to the eye or any surface.

Missed dose, duration, and when to stop

If you miss a dose, take/apply it when you remember unless it’s close to the next dose. Stop immediately and seek care if you develop chest pain, shortness of breath, black/tarry stools, vomiting blood, yellowing of the skin/eyes, or severe skin rash.

Common

• Upset stomach, heartburn, nausea

• Headache, dizziness

• Application‑site irritation (topicals: dryness, itching, redness) 

These typically improve with dose reduction, food, or switching to topical forms.

Serious (seek care urgently)

• Signs of heart attack or stroke (chest pain, shortness of breath, weakness, slurred speech)

• GI bleeding/ulcer (black stools, coffee‑ground vomit, severe stomach pain)

• Liver injury (fatigue, loss of appetite, dark urine, jaundice)

• Kidney issues (less urine, swelling, sudden weight gain)

• Severe skin reactions (blistering rash, peeling)

Cardiovascular risk

All NSAIDs can increase the risk of myocardial infarction and stroke, particularly at higher doses and longer durations. Some evidence suggests diclofenac may carry a higher relative CV risk compared with naproxen or ibuprofen; people with existing heart disease are at special risk. Use the lowest effective dose and avoid use around CABG surgery.

GI bleeding & ulcers

Even short courses can cause serious GI bleeding, ulceration, and perforation, sometimes without warning symptoms. Risk rises with age, prior ulcers, anticoagulants, steroids, heavy alcohol use, and higher doses.

Liver injury (hepatotoxicity)

Diclofenac is a well‑recognized cause of drug‑induced liver injury. Elevations in liver enzymes typically occur in the first 2–6 months, and clinically apparent hepatitis is uncommon but reported. Periodic LFT monitoring is advised for long‑term systemic use; topical forms rarely cause systemic liver effects but case reports exist. Stop and seek care if you develop jaundice or severe fatigue.

Kidney effects & fluid retention

NSAIDs can reduce renal blood flow and trigger acute kidney injury, fluid retention, and hyperkalemia, especially in people with CKD, dehydration, heart failure, or those taking ACE inhibitors/ARBs/diuretics. Monitor and avoid in advanced renal disease unless benefits outweigh risks.

Pregnancy & breastfeeding

The FDA advises avoiding NSAIDs at 20 weeks of pregnancy or later due to risk of low amniotic fluid and fetal kidney problems; after ~30 weeks there’s a risk of premature closure of the ductus arteriosus. If an NSAID is deemed necessary between 20–30 weeks, use lowest dose/shortest duration and consider ultrasound monitoring if >48 hours. Discuss any use while pregnant or breastfeeding with your clinician.

Blood thinners & antiplatelets

Combining diclofenac with warfarin or other anticoagulants/antiplatelets raises bleeding risk. Avoid routine combinations unless your prescriber closely monitors you.

SSRIs/SNRIs & other bleeding‑risk meds

SSRIs/SNRIs (e.g., sertraline, fluoxetine, duloxetine, venlafaxine) also increase bleeding tendency; together with NSAIDs, the risk is higher.

ACE inhibitors/ARBs & diuretics

Diclofenac can blunt the antihypertensive/diuretic effect and increase renal risk; watch BP and kidney function.

Lithium, methotrexate, cyclosporine

NSAIDs can raise lithium levels, increase methotrexate toxicity, and worsen cyclosporine nephrotoxicity, monitor or avoid as directed.

Other NSAIDs, steroids, alcohol

Doubling up on ibuprofen, naproxen, aspirin (unless low‑dose aspirin specifically directed), or oral steroids increases GI bleeding risk. Limit alcohol.