Diclofenac sodium topical gel is an anti-inflammatory pain reliever applied directly to the skin to treat osteoarthritis. It belongs to the same class of drugs as ibuprofen and naproxen (NSAIDs), but because it’s absorbed through the skin rather than swallowed, far less of it enters your bloodstream. The 1% gel is available over the counter under the brand name Voltaren Arthritis Pain, while prescription-strength formulations (including a 2% solution) are also available for specific uses.
Approved Uses and Joints
The FDA approved diclofenac sodium topical gel 1% for relieving the pain of osteoarthritis in joints that are close enough to the skin’s surface for the medication to penetrate effectively. That includes knees, hands, wrists, elbows, feet, and ankles. It was not evaluated for use on the spine, hip, or shoulder, which are deeper joints surrounded by more tissue.
The 2% topical solution is approved specifically for osteoarthritis pain in the knees. Both formulations target the same condition: the chronic joint pain and stiffness that comes from cartilage wearing down over time. This is not a treatment for acute injuries like sprains, muscle soreness from exercise, or inflammatory conditions like rheumatoid arthritis, though some people confuse it for a general-purpose pain gel.
How It Works at the Joint
Like all NSAIDs, diclofenac blocks the enzymes responsible for producing prostaglandins, the chemical messengers that trigger inflammation, swelling, and pain in damaged tissue. When you rub the gel over an arthritic joint, the drug passes through the skin and concentrates in the tissue directly beneath the application site. This delivers anti-inflammatory action right where the osteoarthritis is causing problems.
The key advantage of this local delivery is how little medication reaches the rest of your body. In a crossover study comparing topical diclofenac gel to oral diclofenac tablets, the oral dose produced blood levels 14 to 27 times higher than the topical form, depending on whether the gel was applied to one knee or both. Peak blood concentrations were 87 to 161 times higher with the oral tablets. That difference is why topical diclofenac carries a lower risk of the stomach and cardiovascular side effects traditionally associated with NSAIDs.
How Long It Takes to Work
You may notice some pain relief within the first few days, but the full effect of over-the-counter diclofenac gel typically takes up to 7 days to develop. This is different from popping an ibuprofen tablet and feeling relief within an hour. The gel works by gradually reducing inflammation in the joint tissue over repeated applications, so consistency matters more than any single dose. If you’ve used it daily for a full week without meaningful improvement, that’s generally the point to reassess with a doctor rather than continuing to wait.
How to Apply It
The 1% gel is dosed differently depending on the joint. For lower-body joints like knees, ankles, and feet, a larger amount is used per application. For smaller upper-body joints like hands, wrists, and elbows, less gel is needed. The product comes with a dosing card to measure the correct amount, and it’s applied four times daily for most joints.
A few practical rules make the gel work better and avoid problems. After applying it, wait at least one hour before showering or bathing so the medication has time to absorb. Don’t layer other topical products (sunscreen, lotions, cosmetics) over the same area. Avoid covering the application site with tight bandages or wraps, and wash your hands after applying unless your hands are the joints being treated.
Side Effects to Expect
Skin reactions at the application site are by far the most common side effect, and they’re more common than many people expect. In clinical trials, about 75% of people using diclofenac gel experienced some form of application site reaction during a 60-day treatment period, rising to 84% at 90 days. These reactions ranged from mild to moderate and included:
- Itching: affected 31% at 60 days, 52% at 90 days
- Rash: affected 35% at 60 days, 46% at 90 days
- Dry skin: about 25 to 27% across both timeframes
- Contact dermatitis: 19% at 60 days, 33% at 90 days
- Skin peeling: 6% at 60 days, climbing to 24% at 90 days
These numbers come from trials of a prescription gel formulation used for a skin condition (actinic keratosis), where application was more intensive. Skin reactions with the OTC arthritis gel tend to be milder, but dryness, redness, and itching at the application site are still the side effects you’re most likely to notice.
Digestive side effects like stomach pain, indigestion, and diarrhea occurred in only 4 to 6% of users in clinical trials, which is dramatically lower than what you’d see with oral NSAIDs. A small percentage of users (2 to 3%) showed mild elevations in liver enzymes during trials, though this rarely caused symptoms.
Who Should Avoid It
If you’ve ever had an asthma attack, hives, or allergic reaction after taking aspirin or another NSAID, you should not use diclofenac gel. This type of drug sensitivity can trigger serious reactions even with topical application. You also shouldn’t apply the gel to open wounds, broken skin, or areas with active skin infections or rashes.
People taking blood thinners, other oral NSAIDs, or medications that affect kidney function should be cautious, since even the small amount of diclofenac that reaches the bloodstream can interact with these drugs. The same applies if you have a history of stomach ulcers or significant heart disease. While the systemic exposure is far lower than with pills, it isn’t zero.
Topical vs. Oral NSAIDs
The main trade-off is straightforward. Oral NSAIDs deliver more powerful, whole-body pain relief but carry higher risks for your stomach lining, kidneys, and cardiovascular system. Topical diclofenac concentrates its effect at one or two joints with a fraction of the systemic exposure, making it a better fit for people who need localized relief and want to minimize those risks. It’s particularly useful for older adults, who are more vulnerable to NSAID side effects but also more likely to have osteoarthritis.
The limitation is reach. If you have osteoarthritis in your hip or multiple joints throughout your body, a gel applied to the skin surface simply can’t deliver enough medication to all the places that need it. For superficial joints like the knee or hand, though, studies consistently show topical diclofenac provides meaningful pain relief comparable to oral options for mild to moderate osteoarthritis.