Diclofenac can cause side effects that range from mild to serious. Examples of side effects include kidney problems and sleepiness. If diclofenac side effects become difficult to tolerate, talk with your doctor about coping tips or other treatment options.

Diclofenac is used in adults to treat:

Diclofenac comes in several forms:

  • immediate-release (IR) oral tablet, which is released in your body right away
  • delayed-release (DR) oral tablet, which is released once it enters your stomach
  • extended-release (ER) oral tablet, which is slowly released into your body over a long period of time

Diclofenac also comes in other forms, such as eye drops and topical forms, but this article does not cover them. If you have questions about side effects of other forms, talk with your doctor or pharmacist.

Keep reading to learn about the common, mild, and serious side effects diclofenac can cause. To learn more about this medication, including its uses, dosage, and cost, see this diclofenac DR and ER tablets overview.

Diclofenac has boxed warnings. A boxed warning is the most serious warning from the Food and Drug Administration (FDA). For details, see the “Boxed warnings for diclofenac” section.

Diclofenac can cause certain side effects, some of which are more common than others. These side effects may be temporary, lasting a few days to weeks. Talk with your doctor if side effects do not go away, get worse, or become too difficult to tolerate.

Examples of commonly reported side effects for diclofenac IR oral tablet, diclofenac DR oral tablet, and diclofenac ER oral tablet include:

Mild side effects have been reported with diclofenac IR oral tablet, diclofenac DR oral tablet, and diclofenac ER oral tablet. These include:

  • diarrhea
  • constipation
  • flatulence (gas)
  • abdominal pain
  • indigestion
  • sleepiness
  • tinnitus (ringing in the ears)
  • dizziness
  • headache
  • skin rash
  • itchy skin

In most cases, these side effects should be temporary, and some may be easily managed. But if you have symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. Do not stop diclofenac treatment unless your doctor recommends it.

Diclofenac may cause mild side effects other than those listed here. You can also refer to the prescribing information for diclofenac IR oral tablet, diclofenac DR oral tablet, and diclofenac ER oral tablet.

For more information about some of these side effects, see “Tips for managing side effects.”

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Diclofenac may cause serious side effects. The following list may not include all possible serious side effects of the drug. For more information, you can refer to the prescribing information for diclofenac IR oral tablet, diclofenac DR oral tablet, and diclofenac ER oral tablet.

If you develop serious side effects while taking diclofenac, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Serious side effects that have been reported include:

The use of binary terms such as “male” and “female” in this article reflects the language of the sources we’ve used. Unless otherwise noted, it’s unclear whether the research we reference included participants with expansive gender identities.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. Sharing your experience helps make medication safer for everyone by giving doctors and researchers more information about how the drug works in real life. If you develop a side effect during treatment with diclofenac and want to tell the FDA about it, visit MedWatch or call 800-FDA-1088.

Allergic reaction

For some people, diclofenac can cause an allergic reaction.

In general, symptoms of an allergic reaction can be mild or serious.

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms and can determine whether you should continue diclofenac treatment.

If you have symptoms of a severe allergic reaction, such as swelling or difficulty breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you’ve had a serious allergic reaction to diclofenac, they may have you switch to a different treatment.

Diclofenac has boxed warnings. A boxed warning is the most serious warning from the Food and Drug Administration (FDA).

Risk of serious heart and blood vessel problems

Taking nonsteroidal anti-inflammatory drugs (NSAIDs), including diclofenac, can increase your risk of serious heart and blood vessel problems. This risk is highest when you first start treatment and may increase the longer you take the drug.

Examples of serious heart and blood vessel problems are heart attack and stroke. Signs and symptoms of these conditions may include chest pain, shortness of breath, and weakness in one side of the body.

Other factors that may increase your risk of heart and blood vessel problems include:

  • having a history of heart disease or risk factors for heart disease
  • taking diclofenac within 14 days of having heart bypass surgery
  • taking a high dose of diclofenac
  • taking diclofenac for a long time

Due to this risk, your doctor will likely prescribe diclofenac at the lowest effective dose and for the shortest time needed. If you’ve recently had heart bypass surgery, they’ll likely not prescribe diclofenac.

If you develop any signs or symptoms of heart or blood vessel problems, call 911 or your local emergency number right away.

Risk of serious digestive problems

NSAIDs, such as diclofenac, can increase your risk of serious digestive problems. Examples include bleeding, holes, and ulcers (sores) in your digestive tract. These side effects can occur at any time during treatment and may occur without any warning signs.

Certain factors can increase your risk of digestive problems from diclofenac, including:

Because of this risk, your doctor will likely prescribe diclofenac at the lowest effective dose for the shortest time needed. It’s recommended to only take one NSAID at a time.

Talk with your doctor right away if you develop any symptoms of serious digestive problems. They’ll likely order tests to determine the cause of your symptoms. Your doctor may also discuss whether you’ll need to stop taking diclofenac.

There may be things you can do to help make certain Diclofenac side effects more manageable. If you have ongoing, worsening, or bothersome side effects, talk with your doctor or pharmacist. They can suggest tips for managing them or recommend other available treatment options for your condition.

Sleepiness

Sleepiness was a side effect reported in studies of diclofenac IR oral tablet, diclofenac DR oral tablet, and diclofenac ER oral tablet. Steps you can take to manage symptoms associated with this side effect include:

  • practicing good sleep hygiene, such as keeping to a consistent schedule
  • maintaining a balanced diet
  • staying physically active

Diarrhea

Diarrhea was a common side effect reported in studies of diclofenac IR oral tablet, diclofenac DR oral tablet, and diclofenac ER oral tablet. Steps you can take to manage symptoms associated with this side effect include:

  • staying hydrated
  • taking over-the-counter medications, such as bismuth subsalicylate (Pepto-Bismol) and loperamide (Imodium)
  • avoiding fried or greasy foods

Here are answers to some commonly asked questions about diclofenac’s side effects.

Is weight gain a side effect of diclofenac?

Not likely. Weight gain wasn’t reported in studies of diclofenac IR oral tablet, diclofenac DR oral tablet, and diclofenac ER oral tablet.

But, fluid buildup has occurred in people taking diclofenac oral tablet. In some cases, fluid buildup can lead to weight gain.

If you experience weight gain while taking diclofenac, talk with your doctor.

How long do side effects of diclofenac typically last?

Most side effects of diclofenac should be mild and temporary. They should go away within a few days to weeks.

If you experience side effects that are bothersome or do not go away, talk with your doctor or pharmacist.

Consider the following important information before taking diclofenac.

Diclofenac has a boxed warning. A boxed warning is the most serious warning from the FDA. For details, see the “Boxed warnings for diclofenac” section.

Other precautions

Before taking diclofenac, discuss your health history with your doctor. Diclofenac may not be right for you if you have certain medical conditions or other factors affecting your health. Be sure to talk with your doctor if any of the following apply to you:

  • kidney problems
  • high blood pressure
  • recent heart attack
  • heart failure
  • previous allergic reaction to this or a similar drug
  • pregnancy
  • breastfeeding
  • alcohol consumption

There are also a few factors that are a contraindication to taking diclofenac oral tablets. A contraindication is a factor or condition that could prevent your doctor from prescribing a drug due to the risk of harm. If this applies to you, your doctor likely won’t prescribe diclofenac oral tablet. Those factors or conditions include:

  • recent or planned heart surgery called coronary artery bypass graft (CABG)
  • asthma, hives, or other allergic reactions after taking NSAIDs

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.