Diclofenac gel (Voltaren): what it treats, how to use it, side effects
Last updated September 3, 2026.
Diclofenac gel (brand name Voltaren, now over the counter) is a topical NSAID for osteoarthritis pain in joints you can reach: knees, hands, ankles, feet, elbows, wrists. It delivers the anti-inflammatory through the skin to the joint with a fraction of the systemic exposure of the pill, which is the entire point.
What does it treat?
Osteoarthritis pain of joints amenable to topical treatment, in the label's phrasing: knees and hands chiefly, plus ankles, feet, elbows, wrists. Deep joints like the hip and spine are out of reach of a gel. It is first-line in guidelines for knee and hand OA, especially in older patients where oral NSAIDs are riskiest.
How do you take it?
Four times daily, measured with the dosing card in the box: 4 grams (a card-length ribbon) per knee, ankle, or foot application, 2 grams per hand, elbow, or wrist. Massage it gently into the whole joint area. Caps: 16 g per day on any single lower-extremity joint, 8 g per day on any single upper-extremity joint, 32 g per day total body. Wash hands after (unless treating the hands), let it dry before covering, no shower for at least an hour, and no heat or occlusive bandages over it. Relief builds over days, with full effect by 1 to 2 weeks.
Side effects to know
- Common: application-site reactions: dryness, itching, redness, and dermatitis.
- Serious: the boxed NSAID warning applies even topically, because some drug absorbs: cardiovascular risk (heart attack, stroke) and gastrointestinal bleeding risk, both lower than oral but not zero, and both rising with dose, duration, and your own risk factors. MedlinePlus notes avoiding it around recent bypass surgery.
Who should not take it?
Not with an aspirin/NSAID allergy or aspirin-sensitive asthma, not on broken or infected skin, not with heat packs or tight bandages, and not alongside oral NSAIDs (pick one lane; stacking gel on ibuprofen defeats the safety advantage). Recent heart bypass surgery, prior GI bleeds, and late pregnancy (third trimester, where NSAIDs can harm the fetal heart circulation) are the big cautions.
When is it an emergency?
Call 911 for chest pain, one-sided weakness or slurred speech, black tarry stools or vomiting blood, or a severe allergic reaction. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
Does a gel really work as well as the pills?
For reachable joints, closer than you would expect: trials in knee and hand osteoarthritis show meaningful pain and function gains, and guidelines put topical NSAIDs first for knee and hand OA, ahead of oral ones, precisely because the benefit is comparable and the systemic exposure is a fraction. For hips and spines, no: too deep.
Why four times a day?
Because the drug does not linger in the joint all day the way a long-acting pill hangs around in blood. The 4-times-daily schedule with the dosing card keeps anti-inflammatory levels in the tissue. Most people anchor the four doses to morning, midday, evening, bedtime.
Do I really need the dosing card?
Yes. The card is how the label's gram measurements (4 g for a knee, 2 g for a hand) translate to real life, and the daily caps exist because more gel means more systemic absorption, which erodes the safety advantage you bought by choosing a topical. Eyeballing it drifts upward.
Can I use it and take my ibuprofen too?
You should not stack them. Gel plus oral NSAID is the same drug class twice, and the systemic exposure you were avoiding comes right back. The standard move is the gel replacing the oral NSAID for that joint, with acetaminophen as the systemic backup if breakthrough pain needs one.
How long until my knees feel different?
Some relief in days, the honest trial at 1 to 2 weeks. If four-times-daily, measured-dose application for two full weeks changes nothing, the gel is not the answer for your knees and that is a step-up conversation, not a reason to use more gel.
Is it safe for my heart?
Safer than the pill, not free of risk. Some diclofenac absorbs through skin, so the NSAID cardiovascular warning still applies in reduced form, especially at high doses, long durations, and in people with existing heart disease. Recent bypass surgery and a prior heart attack are explicit caution territory; raise your cardiac history with your prescriber before starting.