Voltaren works by blocking the production of prostaglandins, chemicals your body releases at the site of injury or inflammation that cause pain, swelling, and tenderness. The active ingredient, diclofenac, penetrates through your skin and inhibits two enzymes (COX-1 and COX-2) responsible for making those prostaglandins. With fewer prostaglandins in the tissue, pain and inflammation decrease at the source.
How It Reduces Pain at the Source
When you have joint pain from arthritis or a soft tissue injury, damaged cells trigger the release of prostaglandins. These chemicals sensitize nerve endings, making them fire pain signals more easily, and they also dilate blood vessels, causing the redness and swelling you feel around an inflamed joint. Diclofenac shuts down this process by inhibiting both COX-1 and COX-2 with roughly equal strength. It’s the same basic mechanism that oral anti-inflammatory drugs like ibuprofen use, but delivered directly through the skin to the tissue underneath.
Because the drug reaches the inflamed tissue locally rather than circulating through your entire bloodstream first, it concentrates where you need it. Studies comparing topical diclofenac gel to oral diclofenac tablets found that systemic exposure (the amount of drug circulating in your blood) was 5 to 17 times lower with the gel. That’s a meaningful difference: less drug in your system overall, but a targeted dose right at the painful joint.
How the Gel Penetrates Your Skin
Voltaren isn’t just diclofenac mixed into a cream. The formulation matters enormously for how much drug actually reaches the tissue beneath your skin. The gel’s inactive ingredients help dissolve the drug and carry it through the outermost skin barrier, a tough layer called the stratum corneum that normally keeps substances out. Different Voltaren formulations use different salt forms of diclofenac (sodium or diethylamine), and each interacts with the skin differently.
Research comparing these formulations found striking differences in how much drug gets through. A diclofenac diethylamine emulsion delivered about seven times more of its applied dose through human skin than a higher-concentration diclofenac sodium gel (0.54% versus 0.077% of the applied dose). The thicker, more viscous formulations don’t necessarily work better. What matters is how the drug dissolves within the formulation, releases from it, and moves through the skin layers. This is why not all topical diclofenac products perform the same, even at similar or higher concentrations.
How Quickly You Can Expect Relief
Voltaren isn’t instant, but it’s faster than many people expect from a topical treatment. Limited clinical data suggest pain relief begins within a few hours of application and generally holds through the 12-hour dosing interval. One study that tracked pain ratings hourly found a significant decrease from baseline at the first assessment, just one hour after application. By three hours, the diclofenac group showed clearly greater relief than placebo.
That said, full benefit builds over days of consistent use. Multiple studies in osteoarthritis patients observed meaningful improvement sometime within the first week of regular application. If you use it once and judge it by that single dose, you’re not seeing the full picture. Daily use over several days allows drug levels in the local tissue to build and sustain the anti-inflammatory effect more reliably.
How to Apply It Correctly
Voltaren gel comes with a dosing card to help you measure the right amount. The dose depends on which joint you’re treating:
- Upper body joints (hand, wrist, or elbow): Squeeze out 2.25 inches of gel, which equals about 2 grams. Apply four times a day for a total of 8 grams per joint daily.
- Lower body joints (foot, ankle, or knee): Squeeze out 4.5 inches of gel, about 4 grams. Apply four times a day for a total of 16 grams per joint daily.
If you’re treating more than one joint, the total across all treated areas should not exceed 32 grams per day. You rub the gel gently into the skin over and around the affected joint. Avoid applying it to open wounds, broken skin, or areas with rashes. After application, wash your hands unless your hands are the joint being treated.
Why It’s Gentler Than Oral NSAIDs
One of the main reasons people choose Voltaren gel over swallowing an anti-inflammatory pill is the reduced systemic exposure. Oral NSAIDs circulate throughout your body, which is why they can irritate the stomach lining, stress the kidneys, and raise cardiovascular risk with prolonged use. With topical application delivering 5 to 17 times less drug into the bloodstream, those whole-body risks drop substantially.
The tradeoff is local skin reactions. The most common side effects are mild: dryness, redness, or irritation at the application site. These are generally manageable and tend to resolve when you stop using the product or switch to a different area.
Who Should Not Use It
Voltaren gel is not safe for everyone. You should avoid it if you’ve ever had asthma, hives, or allergic reactions after taking aspirin or other anti-inflammatory drugs. It’s also contraindicated if you have a known allergy to diclofenac itself, or if you’re recovering from coronary artery bypass graft surgery. Even though the topical form puts far less drug into your bloodstream, it still carries the core pharmacology of an NSAID, so these restrictions apply. The product is also not intended for long-term, indefinite use without medical guidance.