Diclofenac belongs to the class of medications known as nonsteroidal anti-inflammatory drugs (NSAIDs). It works by reducing pain, swelling, and inflammation. The topical solution (a lotion applied to the skin) is used to relieve symptoms such as pain associated with osteoarthritis of the knee. This medication should not be used for more than 3 months.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are being given this medication, speak to your doctor. Do not stop using this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to use this medication if their doctor has not prescribed it.

The usual adult dose of diclofenac topical solution is 40 drops applied to the knee 4 times daily at evenly spaced time intervals, or 50 drops applied to the knee 3 times daily at evenly-spaced time intervals.

Apply it only to clean, dry skin.

• Squeeze 10 drops of diclofenac topical solution into the hand or directly onto the knee.
• Spread the solution evenly around the front, back, and sides of the knee.
• Repeat this procedure until 40 drops (if you are using it 4 times daily) or 50 drops (if you are using it 3 times daily) have been applied and the knee is completely covered.
• To treat the other knee, repeat the procedure.
• Allow several minutes for the medication to dry.
• Wash your hands after applying the medication, and avoid contact with eyes or mucous membranes.

Do not apply the medication to infected, abraded, or open skin. Do not use dressings that do not breathe on top of this medication. This medication is for external use only and should not be taken by mouth. It should not be used for longer than 3 months.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are using the medication without consulting your doctor.

It is important to use this medication exactly as prescribed by your doctor. If you miss a dose, skip the missed dose and continue with your regular dosing schedule. Do not administer a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature and keep it out of the reach of children.

Each mL of clear, odourless liquid contains diclofenac sodium 1.5% w/w in a solution base. Nonmedicinal ingredients: dimethyl sulfoxide, glycerine, propylene glycol, ethanol and purified water.

Do not use this medication if you:

• are allergic to diclofenac or to any of the ingredients of the medication
• are allergic to ASA or other NSAIDs (e.g., ibuprofen, ketorolac, diclofenac) or have had allergic symptoms (e.g., runny nose; asthma; itchy skin rash; nasal polyps; swelling of the face, throat, or tongue) caused by these medications
• are planning to have or have recently had heart bypass surgery
• are currently taking other NSAIDs (e.g., ibuprofen, naproxen)
• are pregnant or breast-feeding
• currently have or have recently had inflammatory diseases of the stomach or intestines, such as a stomach or intestinal ulcer or ulcerative colitis
• have severely impaired or deteriorating kidney function
• have severe uncontrolled heart failure
• have significant liver impairment or liver disease
• have high levels of potassium in the blood
• have been using this medication for longer than 3 months

This medication should not be used by children or adolescents less than 18 years of age.

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

• altered sense of taste
• burning, dry, red, itchy, scaly, thickened, or tingling skin at site of application
• constipation
• diarrhea
• dizziness
• dry mouth
• feeling gassy
• hair loss
• headache
• heartburn or indigestion
• mouth sores
• muscle pain
• nausea or stomach upset
• spinning sensation
• thirst
• vomiting

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

• abdominal pain
• abnormal burning, pain, or prickling feeling on skin
• confusion
• difficulty concentrating or thinking
• high blood pressure
• nervousness
• increased frequency of infections (e.g., symptoms may include fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, sore throat, or listlessness)
• signs of clotting problems (e.g., unusual nosebleeds, bruising, blood in urine, coughing blood, bleeding gums, cuts that don't stop bleeding)
• signs of depression (e.g., poor concentration, changes in weight, changes in sleep, decreased interest in activities, thoughts of suicide)
• signs of a liver problem (e.g., yellow skin or eyes, dark urine, pale stools, abdominal pain, or itchy skin)
• signs of a sinus infection (e.g., pain or tenderness around eyes or cheekbones)
• signs of a urinary tract or bladder infection (e.g., pain or burning during urination, frequent urination, blood in the urine)
• symptoms of anemia (e.g., unusual tiredness, weakness, pale skin)
• symptoms of heart failure (e.g., shortness of breath, wheezing, chest tightness, fatigue, cough, fluid retention, swelling in the ankles, legs and feet)

Stop taking the medication and seek immediate medical attention if any of the following occur:

• signs of an allergic reaction (e.g., hives; difficulty breathing; swelling of the face, tongue, or throat)
• signs of heart attack (e.g., sudden chest pain or pain radiating to back, down arm, jaw; sensation of fullness of the chest; nausea; vomiting; sweating; anxiety)
• signs of a severe skin reaction (e.g., blistering, peeling, a rash covering a large area of the body, a rash that spreads quickly, or a rash combined with fever or discomfort)
• signs of stroke (e.g., sudden or severe headache; sudden loss of coordination; vision changes; sudden slurring of speech; or unexplained weakness, numbness, or pain in arm or leg)
• signs of stomach bleeding (e.g., dark tarry stools, blood in the stools, vomiting or coughing up blood or material that looks like coffee grounds)
• swelling of the hands, feet, or ankles
• symptoms of an asthma attack (e.g., increased shortness of breath, wheezing, difficulty breathing, cough, chest tightness, irregular heartbeat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Allergic reactions: If you have had a reaction to acetylsalicylic acid (ASA) or other NSAIDs (e.g., ibuprofen, ketorolac, naproxen) that included a runny nose, itchy skin rash, nasal polyps, or shortness of breath and wheezing, you should not use this medication. If you experience symptoms of a severe allergic reaction (e.g., hives; difficulty breathing; wheezing; swelling of the face, tongue, or throat), get immediate medical attention.

In rare cases, Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS syndrome) may occur. This reaction involves symptoms including fever, swollen glands, yellowing of the skin or eyes, flu-like symptoms with skin rash or blistering, or other organ involvement. Get immediate medical attention if you have symptoms of a severe allergic reaction.

Asthma: People who have or have had asthma should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed. If you have any unusual difficulty breathing while using this medication, contact your doctor immediately.

Drowsiness/reduced alertness: Some people have reported headache, dizziness, lightheadedness, and confusion while using this medication. Avoid operating motor vehicles and doing other potentially hazardous activities until you have determined how this medication affects you.

Heart Problems: When taken by mouth, diclofenac can cause fluid retention and edema (swelling). This can lead to high blood pressure or worsening of heart failure. If you have a history of heart disease or have risk factors for heart disease (e.g., high blood pressure, high cholesterol, diabetes, smoking, kidney disease), discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Hepatic porphyria: This medication may trigger an attack in people with a liver condition known as hepatic porphyria. People with this condition should discuss with their doctor how this medication may affect their medical condition, how their medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Infection: This medication may mask some of the signs of infection, such as fever.

Kidney function: People with reduced kidney function may need lower doses and more frequent medical checkups while using this medication.

Liver function: This medication may cause liver problems. If you have a liver condition, you may need more frequent checkups with your doctor. If you develop signs of a liver problem (such as yellow skin or eyes, dark urine, pale stools, abdominal pain, or itchy skin), stop taking the medication and see your doctor as soon as possible.

Stomach: Stomach ulcers and bleeding from the stomach have been known to occur when diclofenac is taken by mouth. These complications can occur at any time and are sometimes severe enough to require immediate medical attention. Although these reactions have not been known to occur with diclofenac topical solution, you should seek medical attention immediately if you notice any signs of bleeding (such as dark, tarry stools, blood in the stools, or vomiting material that looks like coffee grounds).

Sun sensitivity: This medication may make your skin more sensitive to the sun. While you are using this medication, avoid excessive sun exposure, including tanning beds and sun lamps. If you experience sunburn with itching, swelling, and blistering, stop using this medication and contact your doctor.

Vision: Other medications in the same family as diclofenac may cause vision changes such as blurred or decreased vision. If you notice vision changes, stop using the medication and check with your doctor.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If diclofenac is taken during the earlier stages of pregnancy, there is also an increased risk of miscarriage. Use of diclofenac at 20 weeks or later in pregnancy may increase the risk of kidney damage and complications due to low amniotic fluid in the developing baby. When diclofenac is taken during the last 3 months of pregnancy, there is an increased risk of the child developing heart problems and the mother having a longer labour to deliver the baby. If you become pregnant while taking this medication, contact your doctor as soon as possible. If you become pregnant while using this medication, stop using it immediately and call your doctor.

Breast-feeding: It is not known if diclofenac topical solution passes into breast milk. This medication is not recommended for breast-feeding women.

Children: Diclofenac topical solution should not be used by children.

Seniors: Seniors may have a higher risk of side effects with this medication. Seniors may need lower doses of this medication and more frequent medical checkups.

There may be an interaction between diclofenac and any of the following:

• alcohol
• alpha agonists (e.g., clonidine, methyldopa)
• alpha blockers (e.g., alfuzosin, doxazosin, silodosin, tamsulosin)
• angiotensin converting enzyme inhibitors (ACEIs; captopril, ramipril)
• angiotensin receptor blockers (ARBs; e.g., candesartan, irbesartan, losartan)
• beta-adrenergic blockers (e.g., atenolol, propranolol, sotalol)
• bisphosphonates (e.g., alendronate, etidronate, pamidronate, risedronate, zoledronic acid)
• calcium channel blockers (e.g., amlodipine, diltiazem, nifedipine, verapamil)
• celecoxib
• corticosteroids (e.g., prednisone, hydrocortisone, methylprednisolone)
• cyclosporine
• deferasirox
• digoxin
• diuretics (water pills; e.g., furosemide, hydrochlorothiazide, triamterene)
• fludrocortisone
• fluoroquinolone antibiotics (e.g., ofloxacin, ciprofloxacin)
• herbal medications that affect blood clotting (e.g., ginkgo biloba, garlic, ginger, ginseng, glucosamine)
• lithium
• medications that affect blood clotting, such as acetylsalicylic acid (ASA, aspirin), apixaban, clopidogrel, enoxaparin, dalteparin, heparin, rivaroxaban, tinzaparin, or warfarin
• methotrexate
• other nonsteroidal anti-inflammatory drugs (NSAIDs; e.g., ibuprofen, naproxen, ketorolac)
• phenytoin
• serotonin/norepinephrine reuptake inhibitors (SNRIs; e.g., desvenlafaxine, duloxetine, venlafaxine)
• selective serotonin reuptake inhibitors (SSRIs; e.g., paroxetine, fluoxetine, citalopram, sertraline)
• tacrolimus
• voriconazole

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

• stop taking one of the medications,
• change one of the medications to another,
• change how you are taking one or both of the medications, or
• leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.