Diclofenac Topical (arthritis pain)

Diclofenac topical gel is used to relieve joint pain caused by osteoarthritis in areas that can be reached through the skin.

• Knees — the most commonly treated joint
• Hands (including fingers, palm, and back of the hand)
• Wrists
• Ankles and feet
• Elbows

Not studied or recommended for the spine, hip, or shoulder.

Diclofenac is an NSAID that works by blocking an enzyme called cyclooxygenase (COX). This enzyme is a key step in your body's production of prostaglandins — chemicals that signal pain, promote swelling, and drive inflammation. By blocking COX at the site where you apply the gel, diclofenac reduces those pain and inflammation signals locally in the joint.

Because the gel is applied to the skin rather than swallowed, much less of the drug reaches your bloodstream compared to an oral NSAID — roughly 17 times less with typical use on one knee. This local action is a key reason the topical form is used for accessible joints.

Apply the gel to the affected joint four times daily, gently massaging it into the entire area. Use the dosing card included in the box to measure the right amount each time — lower-extremity joints like the knee get a larger measured dose, and upper-extremity joints like the wrist or hand get a smaller one.

• Do not exceed the daily limit for any single joint
• Do not exceed the total daily limit across all treated joints
• If treating your hands, wait at least one hour before washing them
• Rinse and dry the dosing card after each use

Always follow your prescriber's specific instructions. This medication does not need to be taken with food since it is not swallowed.

The most common side effects are reactions right where you apply the gel.

• Skin dermatitis (irritation or inflammation) at the application site — the most frequently reported reaction
• Redness, itching, or rash at the treated area
• Dry or scaly skin at the application site
• Skin discoloration where the gel is applied

More serious reactions — such as stomach bleeding, chest pain, signs of stroke, severe skin reactions like blistering or peeling, or signs of allergic reaction (throat swelling, trouble breathing) — are less common but require immediate medical attention. Stop using the gel and call your doctor or 911 right away if any of these occur.

• Heart attack and stroke: All NSAIDs, including this gel, can raise the risk of serious and potentially fatal cardiovascular events. The risk may increase with duration of use. Use the lowest effective amount for the shortest time, especially if you have heart disease or risk factors for it.
• Stomach and intestinal bleeding: Can occur without warning at any time during treatment and can be fatal. Older adults are especially vulnerable. Watch for dark or bloody stools, stomach pain, or vomiting blood.
• Liver effects: Liver enzyme levels may rise during treatment. Stop using and contact your doctor if you develop jaundice (yellowing of skin or eyes) or unexplained abdominal pain.
• Kidney effects: Long-term use can harm the kidneys. Higher risk in older adults, people with kidney or heart problems, and those taking diuretics or ACE inhibitors.
• High blood pressure and fluid retention: Monitor blood pressure during use. Stop use if significant swelling or fluid retention develops.
• Severe skin reactions: Rare but potentially fatal skin conditions (such as Stevens-Johnson Syndrome) can occur. Discontinue immediately if a rash or skin reaction develops.
• Severe allergic reactions: Can occur even without a prior reaction to the drug. Stop use immediately and get emergency help if signs of anaphylaxis appear.

Diclofenac topical gel can interact with several common medications, raising the risk of serious side effects.

• Aspirin: Using both together is generally not recommended — it can increase the risk of GI bleeding and other adverse effects.
• Blood thinners (e.g., warfarin): The combination significantly raises the risk of serious stomach or intestinal bleeding.
• ACE inhibitors (e.g., lisinopril): Diclofenac may reduce their blood-pressure-lowering effect.
• Diuretics (water pills, e.g., furosemide, thiazides): Diclofenac may weaken their effect and increase the risk of kidney problems; kidney function should be watched closely.
• Lithium: Diclofenac can raise lithium blood levels, increasing the risk of lithium toxicity — watch for signs like tremor, confusion, or nausea.
• Methotrexate: Diclofenac may increase methotrexate's toxicity; careful monitoring is needed.
• Cyclosporine: Caution is advised when used together due to potential interaction.

This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.

• Allergy to diclofenac, aspirin, or any NSAID: Do not use — serious and potentially fatal allergic reactions have occurred.
• Asthma or allergic reactions triggered by aspirin or NSAIDs: Do not use.
• Recent or upcoming CABG (heart bypass) surgery: This medication is contraindicated around that surgery.
• History of heart disease or risk factors (high blood pressure, high cholesterol, diabetes, smoking): Use with caution and use the lowest effective amount.
• History of stomach ulcers or GI bleeding: Use with caution; inform your prescriber.
• Kidney disease, liver disease, or heart failure: Use with caution; close monitoring needed.
• Taking diuretics or ACE inhibitors: Kidney function should be monitored.
• Pregnancy: Safety has not been established. Avoid in late pregnancy — it may cause premature closure of a vital blood vessel in the baby's heart. Discuss use in any trimester with your doctor.
• Breastfeeding: Unknown if diclofenac passes into breast milk; discuss the risks and benefits with your doctor before using.
• Children: Safety and effectiveness in patients under 18 have not been established.
• Older adults: At higher risk for serious GI events and kidney effects — use with extra caution.

If a large amount of this gel is accidentally swallowed, symptoms can include drowsiness, nausea, vomiting, and stomach pain — and in serious cases, high blood pressure, kidney failure, or difficulty breathing. If accidental ingestion occurs, call Poison Control immediately at 1-800-222-1222 or go to the nearest emergency room. Do not induce vomiting unless directed to do so by medical personnel.

Diclofenac has three main effects in the body: it reduces inflammation, relieves pain (anti-nociception, meaning it lowers the body's pain-signaling activity), and reduces fever (antipyretic). These effects come from its ability to block the production of prostaglandins, thromboxanes, and prostacyclin — chemicals that play a central role in the body's pain and inflammatory responses. When applied to the skin, these effects are concentrated in the local tissues near the treated joint.

Because this medication is applied to the skin rather than swallowed, the amount that reaches your bloodstream is dramatically lower than with oral diclofenac — on average about 17 times less with typical single-knee use. In practical terms, blood levels from the gel are a small fraction of what you'd get from taking diclofenac pills. This reduced systemic (whole-body) absorption is one of the key benefits of the topical form. Applying heat to the treated area before using the gel may affect how much is absorbed, so avoid heating pads or hot packs on the application site.

Store at 20°C to 25°C (68°F to 77°F). Store the dosing card with your diclofenac sodium topical gel.