Voltaren Arthritis Pain Gel contains 1% diclofenac sodium as its active ingredient, a nonsteroidal anti-inflammatory drug (NSAID) that reduces pain and swelling at the joint. The remaining 99% is a blend of inactive ingredients designed to help the drug absorb through your skin, give the gel its texture, and keep it stable on the shelf. Here’s what each component does and why it’s there.
The Active Ingredient: Diclofenac Sodium
Diclofenac sodium is the ingredient that actually relieves pain. It works by blocking enzymes called COX-1 and COX-2, which your body uses to produce chemicals that trigger inflammation and pain signals. By suppressing those chemicals right at the joint, diclofenac reduces swelling, stiffness, and soreness from osteoarthritis.
At 1% concentration, every gram of gel contains 10 milligrams of diclofenac. That might sound like a lot when you’re applying multiple grams per day, but very little of it reaches your bloodstream. An FDA pharmacology review found that the gel’s bioavailability is roughly 6.6% compared to an oral diclofenac tablet. Peak blood levels from the gel run about 2% of what you’d see after swallowing a pill. That’s the whole point of a topical formulation: deliver the drug locally, where it’s needed, while keeping systemic exposure low.
The Full Inactive Ingredient List
According to the product’s DailyMed listing, the inactive ingredients are:
- Carbomer homopolymer Type C
- Cocoyl caprylocaprate
- Fragrance
- Isopropyl alcohol
- Mineral oil
- Polyoxyl 20 cetostearyl ether
- Propylene glycol
- Purified water
- Strong ammonia solution
Each of these serves a specific purpose, from creating the gel’s consistency to helping diclofenac penetrate the skin barrier.
What the Inactive Ingredients Actually Do
Carbomer homopolymer Type C is the thickening agent that gives Voltaren its gel consistency. Without it, the formula would be a thin liquid that runs off your skin before the drug could absorb. The carbomer forms a smooth, spreadable base that holds the diclofenac in contact with your skin long enough to work.
Isopropyl alcohol and propylene glycol serve as penetration enhancers. Your skin is designed to keep things out, which makes delivering a drug through it a challenge. Isopropyl alcohol helps the diclofenac dissolve and temporarily disrupts the skin’s outer barrier so the drug can pass through. Propylene glycol works similarly. Research on diclofenac gels has shown that propylene glycol content significantly influences how much drug crosses the skin, with certain concentrations boosting penetration several times over.
Cocoyl caprylocaprate and mineral oil act as emollients, softening the skin and helping the gel spread evenly. Polyoxyl 20 cetostearyl ether is an emulsifier that keeps the oil-based and water-based components mixed together so the gel stays uniform rather than separating in the tube. Purified water makes up the bulk of the gel’s volume and serves as the primary solvent.
The strong ammonia solution adjusts the gel’s pH. Carbomer gels need a slightly alkaline environment to thicken properly, and a small amount of ammonia brings the pH to the right range. The quantity is tiny and evaporates quickly. The added fragrance gives the gel a mild scent, masking what would otherwise be a chemical smell from the alcohol and other ingredients.
How Much to Apply and Where
The labeled dose depends on which joint you’re treating. For upper body areas like a hand, wrist, or elbow, you squeeze out 2.25 inches of gel, which works out to about 2 grams. For lower body areas like a knee, ankle, or foot, you use 4.5 inches, roughly 4 grams. You apply it four times a day, every day, and you shouldn’t treat more than two body areas at the same time.
Don’t expect immediate results. Most people need about 7 days of consistent daily use before they notice significant pain relief. Voltaren Gel is designed for ongoing management of arthritis pain, not as a quick fix for a sudden flare.
Why Low Absorption Matters for Safety
All NSAIDs, including diclofenac, carry warnings about cardiovascular and gastrointestinal risks. The FDA requires these warnings on Voltaren Gel’s label just as it does for oral NSAIDs. But the gel’s dramatically lower systemic exposure changes the practical risk profile. With peak blood levels at roughly 2% of an oral dose, the gel delivers far less drug to your heart, stomach lining, and liver than a pill would.
Liver enzyme elevations above three times the normal limit have been reported in about 3.5% of diclofenac users, but almost entirely with the oral form. Published medical literature contains only two reported cases linking topical diclofenac to liver enzyme problems, and even those lack strong evidence of a direct cause.
Who Should Avoid It
If you’ve ever had hives, facial swelling, or an asthma attack after taking aspirin or another NSAID like ibuprofen or naproxen, you should not use Voltaren Gel. These reactions are typically driven by COX-1 enzyme inhibition, and diclofenac inhibits the same enzyme. Cross-reactivity is well documented: people who react to one strong COX-1 inhibitor can react to others, regardless of whether the drug is swallowed or rubbed on the skin.
Diclofenac is also one of the NSAIDs most commonly associated with contact dermatitis, a localized skin reaction at the application site. If you develop a rash, redness, or itching where you apply the gel, that’s a sign to stop using it and try a different approach to pain management.