How does this medication work? What will it do for me?

This medication belongs to the class of medications known as non-steroidal anti-inflammatories (NSAIDs). It is used to treat mild to moderate pain with inflammation. It may be used for muscle aches and pains, tooth extraction, and symptoms of rheumatoid arthritis and osteoarthritis. It works by relieving pain and reducing inflammation. Diflunisal produces significant pain relief within one hour and maximum relief after 2 to 4 hours. Pain relief lasts for 8 to 12 hours.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking 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 take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

Nu-Diflunisal is no longer being manufactured for sale in Canada. For brands that may still be available, search under diltiazem. This article is being kept available for reference purposes only. If you are using this medication, speak with your doctor or pharmacist for information about your treatment options.

How should I use this medication?

The recommended adult dose of diflunisal for the treatment of rheumatoid arthritis and osteoarthritis ranges from 500 mg to 1,000 mg daily, in two divided doses with food or milk.

For the relief of pain associated with other types of inflammation, the usual dose is 500 mg every 12 hours. In some cases, such as for seniors or people with a low body weight, a smaller dose of 250 mg every 12 hours may be used.

Diflunisal produces significant pain relief within one hour and maximum relief after 2 to 4 hours. Pain relief lasts for 8 to 12 hours. Do not crush or chew the tablets.

Many things can affect the dose of 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 taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take 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, protect it from moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Diflunisal should not be taken by anyone who:

  • is allergic to diflunisal or to any of the ingredients of the medication
  • is currently taking NSAIDs
  • is planning to have or recently had heart bypass surgery
  • currently has or recently had inflammatory diseases of the stomach and intestines such as stomach or intestinal ulcer or ulcerative colitis
  • has had an allergic reaction to ASA or other anti-inflammatory medications
  • has high levels of potassium in the blood
  • has severely impaired or deteriorating kidney function
  • has significant liver impairment or liver disease

What side effects are possible with this medication?

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.

  • abdominal or stomach cramps, pain, or discomfort (mild to moderate)
  • diarrhea
  • dizziness, drowsiness, or lightheadedness
  • headache (mild to moderate)
  • heartburn, indigestion, nausea, or 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:

  • bladder pain
  • bleeding from cuts or scratches that lasts longer than usual
  • bleeding or crusting sores on lips
  • bloody or cloudy urine or any problem with urination, such as difficult, burning, or painful urination
  • burning feeling in throat, chest, or stomach
  • change in urine colour or odour
  • confusion, forgetfulness, mental depression, or other mood or mental changes
  • cough or hoarseness
  • decreased hearing, any other change in hearing, or ringing or buzzing in ears
  • difficulty swallowing
  • eye pain, irritation, dryness, redness, or swelling
  • frequent urge to urinate
  • hallucinations
  • headache (severe), throbbing, or with stiff neck or back
  • increased blood pressure
  • light-coloured stools
  • muscle cramps, pain, or weakness
  • numbness, tingling, pain, or weakness in hands or feet
  • pain in lower back or side (severe)
  • sudden, large increase or decrease in the amount of urine or loss of bladder control
  • swelling of face, feet, or lower legs
  • swelling of lips or tongue
  • swollen or painful glands (especially in the neck or throat area)
  • swelling or tenderness in upper abdominal or stomach area
  • thirst (continuing)
  • unexplained runny nose or sneezing
  • unexplained, unexpected, or unusually heavy vaginal bleeding
  • unusual tiredness or weakness
  • weight gain (rapid)
  • yellow eyes or skin

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

  • abdominal or stomach pain, cramping, or burning (severe)
  • bloody or black, tarry stools
  • blurred vision or any change in vision
  • chest pain
  • convulsions (seizures)
  • fainting
  • fast or irregular breathing
  • fast, irregular heartbeat or pulse
  • fever with or without chills
  • hive-like swellings (large) on face, eyelids, mouth, lips, or tongue
  • hives, itching of skin, or any other skin problem (such as blisters, redness or other colour change, tenderness, burning, peeling, loosening or splitting of fingernails)
  • nausea, heartburn, or indigestion (severe and continuing)
  • pinpoint-sized red spots on skin
  • puffiness or swelling of the eyelids or around the eyes
  • shortness of breath, troubled breathing, wheezing, or tightness in chest
  • sores, ulcers, or white spots on lips or in mouth
  • spitting up of blood
  • trouble speaking
  • unexplained nosebleeds
  • unusual bleeding or bruising
  • vomiting of blood or material that looks like coffee grounds

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.

Are there any other precautions or warnings for 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.

Drowsiness/reduced awareness: Headache, dizziness, lightheadedness, and confusion have been reported by some people using this medication. Avoid operating machinery or motor vehicles or doing other potentially hazardous tasks until you determine how this medication affects you.

Fluid and electrolyte balance: Fluid retention and edema have been reported with use of this medication. People who have the following conditions should be monitored by their doctor while taking this medication:

  • certain heart conditions (e.g., congestive heart failure)
  • high blood pressure
  • kidney disease or impaired kidney function
  • liver disease
  • recovering from surgical operations under general anesthesia
  • other conditions that might lead to fluid retention

There is a risk of high blood potassium with treatment with diflunisal. People most at risk are seniors, those having conditions such as diabetes or kidney failure, and those taking beta-adrenergic blockers, angiotensin converting enzyme (ACE) inhibitors, or some diuretics (water pills).

Heart problems: NSAID medications may increase the risk of heart attacks, strokes, and blood clots. The risk is greater with higher doses and long-term use. People at risk of heart problems, such as those with high blood pressure, high cholesterol, diabetes, peripheral arterial disease, heart failure, or coronary artery disease, 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 the signs of an infection, such as a fever.

Kidney function: Long-term use of diflunisal may lead to a higher risk of reduced kidney function. This is most common for people who already have kidney disease, liver disease, or heart failure; for people who take diuretics (water pills); and for seniors.

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 problems: Stomach ulcers, perforation, and bleeding from the stomach have been known to occur while taking diflunisal. These complications can occur at any time, and are sometimes severe enough to require immediate medical attention. The risk of ulcers and bleeding are increased in people taking higher doses of diflunisal for longer periods of time.

Diflunisal should be taken under close medical supervision by people prone to irritation of the stomach and intestines, particularly those who have had a stomach ulcer, bloody stools, or diverticulosis or other inflammatory disease of the stomach or intestines (such as ulcerative colitis or Crohn's disease). In these cases, your doctor must weigh the benefits of treatment against the possible risks.

Stop taking the medication and contact your doctor immediately if you experience symptoms or signs suggestive of stomach ulcers or bleeding in the stomach (black, tarry stools). These reactions can occur at any time during treatment without warning.

Pregnancy: This medication is not recommended for use during pregnancy as its safety has not been established.

Breast-feeding: This medication passes into breast milk and should not be used by breast-feeding mothers.

Children: ASA has been associated with Reye's syndrome and because diflunisal has similarities to ASA, an association with Reye's syndrome is also possible. Talk to your doctor if your child, adolescent, or teen has influenza, infections of the upper espiratory tract, and chickenpox, as these conditions may increase the risk of Reye's syndrome. Diflunisal is not recommended for children under 12 years of age. The safety, effectiveness, and dosages of this medication for this age group have not been established.

Seniors: Seniors appear to have a higher risk of side effects. They should use the lowest effective dosage under close medical supervision.

What other drugs could interact with this medication?

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

  • acetaminophen
  • alcohol
  • angiotensin II receptor blockers (ARBs; e.g., candesartan, irbesartan)
  • angiotensin converting enzyme (ACE) inhibitors (e.g., ramipril)
  • antidiabetes medication (e.g., glyburide, gliclazide)
  • beta-blockers (e.g., metoprolol, atenolol)
  • bisphosphonates (e.g., alendronate, etidronate, pamidronate, risedronate, zoledronic acid)
  • cholestyramine
  • colestipol
  • corticosteroids (e.g., prednisone)
  • cyclosporine
  • desmopressin
  • diuretics (water pills; e.g., furosemide, hydrochlorothiazide, spironolactone)
  • digoxin
  • fluoroquinolone antibiotics (e.g., ofloxacin, ciprofloxacin)
  • herbal medications that affect blood clotting (e.g., ginkgo biloba, garlic, ginger, ginseng, glucosamine)
  • lithium
  • medications used to treat stomach or intestinal ulcers, reflux, or excessive acidity (e.g., ranitidine, omeprazole, esomeprazole, pantoprazole)
  • medications that affect blood clotting, such as acetylsalicylic acid (ASA, aspirin), clopidogrel, enoxaparin, dalteparin, heparin, lepirudin, tinzaparin, or warfarin
  • methotrexate
  • other NSAIDs (e.g., naproxen, indomethacin)
  • other products containing diflunisal
  • pentoxifylline
  • phenytoin
  • potassium supplements
  • probenecid
  • pemetrexed
  • SSRIs (e.g., paroxetine, fluoxetine, citalopram, sertraline)
  • sulfinpyrazone
  • tacrolimus
  • tricyclic antidepressants (e.g., amitriptyline, doxepin, imipramine)
  • 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.