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Rx pill pad and prescription pad: Diclofenac side effects and how to avoid them
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Diclofenac side effects and how to avoid them

Gastrointestinal problems, heart problems, and skin and drug reactions are some common diclofenac side effects
Karen Berger medical writer and reviewer headshot
By | Nov. 8, 2022

Common diclofenac side effects | Serious side effects | Gastrointestinal problems | Heart problems | Allergic, skin, or drug reactions | Side effects timeline | Contraindications | Warnings | Interactions | How to avoid side effects | How to treat side effects

Diclofenac is a prescription drug that is part of a class of medications called non-steroidal anti-inflammatory drugs, or NSAIDs. If you have ever had any type of back pain, inflammation, or other injury, you may have taken an NSAID. Some popular NSAIDs include oral tablets like aspirin, Advil and Motrin (ibuprofen), and naproxen, among others. NSAIDs like diclofenac can help with pain, inflammation, and fever. Diclofenac works by preventing enzymes called COX-1 and COX-2 from making prostaglandin. Prostaglandin causes pain, inflammation, and fever. By decreasing the production of prostaglandin, symptoms of pain, inflammation, and fever can improve. 

There are various forms of diclofenac. This article will focus on oral diclofenac sodium. Diclofenac sodium is a prescription medicine that is approved by the FDA. Diclofenac may sometimes be referred to as the brand-name drugs Voltaren (delayed-release tablets) and Voltaren-XR (extended-release tablets). However, these brand names are no longer available in the US—only the generic versions of oral diclofenac are available. Diclofenac sodium is used to treat symptoms of various conditions such as:

For reference, there are different forms of diclofenac. Other forms of this medication that are available by prescription include:

  • Arthrotec (diclofenac/misoprostol): treats symptoms of osteoarthritis and rheumatoid arthritis and includes misoprostol to protect the stomach
  • Cambia (diclofenac powder): treats acute migraine headache
  • Cataflam (diclofenac potassium tablets): treats symptoms of osteoarthritis, rheumatoid arthritis, menstrual pain, mild to moderate pain
  • Diclofenac gel: a topical diclofenac gel that treats joint pain
  • Flector (diclofenac) transdermal patch: treats acute pain
  • Pennsaid (diclofenac) solution: treats symptoms of knee osteoarthritis
  • Solaraze (diclofenac) topical gel: treats actinic keratosis
  • Voltaren (diclofenac) ophthalmic (eye drops): treats eye inflammation after cataract surgery; also is used before and after corneal refractive surgery
  • Zipsor: (diclofenac capsules): treats mild to moderate pain 
  • Zorvolex (diclofenac capsules): treats mild to moderate pain and symptoms of osteoarthritis

Diclofenac is also available over-the-counter as a topical medication to treat joint pain. Some medications that are available OTC and contain diclofenac include Voltaren Arthritis Pain, Aspercreme Arthritis Pain, Dr. Scholl’s Arthritis Pain Reliever, and Salonpas Arthritis Pain Relief Gel. 

Common side effects of diclofenac

Patients who take diclofenac may experience stomach problems as a common side effect—this may include indigestion, stomach pain, nausea, vomiting, diarrhea or constipation, and/or gas. 

Other common side effects of oral diclofenac include:

  • Headache
  • Dizziness 
  • Skin reactions such as rash, itching, hives
  • Increased liver function tests
  • Drowsiness 
  • Swelling of the extremities (legs, ankles, feet, hands, arms)
  • Ringing in the ears 
  • Bruising
  • Sun sensitivity (patients should avoid the sun as much as possible when taking diclofenac and use extra caution when in the sun, wearing protective clothing and applying sunscreen)
  • Delayed ovulation (women who are trying to conceive or having trouble conceiving should consult their health care provider for medical advice)

Serious side effects of diclofenac

Before taking diclofenac, tell your doctor about any medical conditions you have, as well as family history and medical history. Serious possible side effects of oral diclofenac may include:

Diclofenac and gastrointestinal problems

Any NSAID, including diclofenac, can cause serious gastrointestinal (GI) problems including inflammation, bleeding, ulceration (sores), and perforation (holes) of the stomach, esophagus, or intestines, which can cause death. These events can happen at any time, with or without warning symptoms. Only about 20% of patients who take an NSAID and develop a GI complication have symptoms. In clinical studies, ulcers, bleeding, and perforation due to NSAIDs occurred in about 1% of patients who took an NSAID for three to six months, and in about 2-4% of patients who took an NSAID for one year. 

Individuals with a history of stomach problems such as ulcers or bleeding have more than 10 times the risk for developing GI complications from an NSAID than those who do not have risk factors. Other risk factors include:

Those who take NSAIDs should be prescribed the lowest effective dose for the shortest possible time and should be closely monitored. 

Diclofenac and heart problems

NSAIDs, including diclofenac, can increase the risk of serious heart events, such as heart attack and stroke, which can cause death. Individuals with heart disease or other risk factors have a higher incidence of serious heart events. These complications can occur early in treatment, or at any time. As with GI problems, patients who take NSAIDs should be prescribed the lowest effective dose for the shortest time and should be closely monitored. 

NSAIDs should never be used before or after coronary artery bypass graft (CABG) surgery. In most cases, NSAIDs should not be used after a heart attack. 

Diclofenac and allergic, skin, or drug reactions

NSAIDs like diclofenac can cause a severe allergic reaction. Patients who experience signs of an allergic reaction, such as hives, difficulty breathing, or swelling of the face, lips, tongue, or throat, should get emergency medical help. 

Diclofenac can cause serious or life-threatening skin reactions that require emergency medical attention. Patients should be alert to fever, burning eyes, sore throat, red or purple rash (or any kind of skin rash), and/or blistering or peeling skin. These symptoms require emergency medical attention. 

Diclofenac may also cause a serious drug reaction that could potentially affect many parts of the body. Symptoms may include rash, fever, swollen glands, weakness, muscle aches, bruising, or yellowing of the skin or whites of the eyes. 

How soon do diclofenac side effects start?

Many patients have only mild side effects, especially with a short course of treatment. Stomach problems, such as diarrhea, stomach pain, and heartburn, tend to occur fairly quickly in treatment. 

More serious stomach problems like bleeding, perforations, and ulcers, can occur at any time during treatment, with or without warning. Other serious problems like heart attack, blood clots, serious skin reactions, and pancreas, kidney, or liver problems, may occur after a period of time of diclofenac treatment. 

Before taking diclofenac, ask your healthcare provider for more information about risk factors for side effects, what side effects to expect, what to do if they occur, and any other questions you may have. 

How long do diclofenac side effects last?

Mild stomach problems, like heartburn or diarrhea, may go away in a few days as your body adjusts to the medicine. 

Other side effects can be more serious, with longer-lasting effects (see next section). 

If you experience any side effects that cause concern or that do not go away, consult your healthcare provider. Seek emergency medical help if symptoms are more urgent, such as swelling, trouble breathing, or any changes in the skin such as rashes, blistering, or peeling.

What are the long-term side effects of diclofenac?

Many people who take diclofenac will only experience mild side effects. It is important to take diclofenac exactly as prescribed—this may help avoid more severe or long-term side effects or complications. Many side effects are mild and tend to go away as you adjust to the medicine, like stomach upset or drowsiness. 

Some long-term side effects, if diclofenac is taken for a period of time, may include anemia (low red blood cells), kidney problems, and liver problems. However, diclofenac is generally prescribed at the lowest dose and for the shortest time possible, which can help avoid many long-term side effects.

 Serious side effects, including stomach ulcers, bleeding, and perforation, can occur at any time during treatment. These can lead to long-term complications. Heart attacks, strokes, and kidney problems are other possible, but rare, problems that could occur, causing long-term complications. 

Diclofenac contraindications

Before using diclofenac, patients should consult their healthcare provider, and review their medical conditions and history. Diclofenac is not safe for everyone to take. It is contraindicated (should not be taken) for certain individuals. Diclofenac should not be used in:

  • People who are allergic to diclofenac, any NSAID, or any ingredient in the medication
  • People with aspirin-induced or NSAID-induced asthma or hives
  • People with aspirin triad (individuals who have all 3: aspirin or NSAID allergy, asthma, and sinus disease with nasal polyps)
  • People who are undergoing CABG surgery (heart bypass surgery)
  • People with severe kidney disease/poor kidney function
  • Pregnant women starting at 30 weeks of pregnancy (diclofenac could harm the unborn baby)

Diclofenac may or may not be used in certain other patients. If it is used, diclofenac should be used cautiously and with close monitoring. These individuals include:

  • Pregnant women before 30 weeks of pregnancy
  • Older adults
  • Debilitated (in a weakened state) patients 
  • People with kidney problems
  • People with liver disease/liver problems
  • People with asthma
  • People who have had a recent heart attack
  • People with heart disease (cardiovascular disease), or who are at risk for heart disease due to risk factors or a family history of heart disease
  • People with high blood pressure
  • People with congestive heart failure (CHF)
  • People with fluid retention
  • People with blood clotting disorders
  • People with a history of GI bleeding or ulcers
  • People who smoke or use alcohol
  • People who are dehydrated
  • Women who are trying to conceive
  • People who take diclofenac for a long time (this increases the risk of serious complications)

Diclofenac warnings

Diclofenac black box warning

A black box warning is the strongest warning required by the United States Food and Drug Administration (FDA). Diclofenac—as well as all NSAIDs—have a black box warning. This warning states:

  • NSAIDs cause an increased risk of serious heart and clotting complications, including heart attack and stroke, which can cause death. This risk can occur early in treatment and may increase the longer the medication is taken. 
  • Diclofenac should not be taken before or after CABG surgery.
  • NSAIDs cause a greater risk of serious GI problems including bleeding, ulcers, and perforation of the stomach or intestines, which can cause death. These can occur at any time during diclofenac use, with or without warning symptoms. Certain patients are at higher risk, including older adults and patients with a history of ulcers or GI bleeding. 

Is diclofenac a controlled substance?

Diclofenac is not a controlled substance and is not habit-forming. Other NSAID treatment options are not controlled substances, either.

Diclofenac overdose

Taking too much diclofenac may cause low energy, drowsiness, nausea, vomiting, and abdominal pain. Other problems that may occur in rare cases include GI bleeding, high blood pressure, kidney problems, respiratory depression, and coma. If you think you took too much diclofenac, consult your healthcare provider right away, or call Poison Control at 1-800-222-1222. If your symptoms are severe or life-threatening, call 911 and go to the emergency room. 

Diclofenac interactions

Before taking diclofenac, tell your healthcare professional about any allergies to medications and all the medications you take. This includes prescription and OTC drugs, vitamins, and supplements.

Some interactions with diclofenac include:

  • Toradol (ketorolac) should never be taken with diclofenac. The combination could increase the risk of GI ulcers, perforation, and bleeding, which could be life-threatening. This combination could also cause high blood pressure, kidney problems, and other complications. 
  • Avoid consuming alcohol while taking diclofenac. The combination of diclofenac and alcohol can increase the risk of GI ulcers, perforation, and bleeding, which could be life-threatening. 
  • While taking diclofenac, avoid excessive caffeine intake, which could increase the risk of high blood pressure.
  • Diuretics (water pills) combined with diclofenac could increase the risk of kidney problems. If the combination cannot be avoided, kidney function should be closely monitored.
  • Diclofenac combined with certain medications can increase the risk of bleeding. These drugs include blood thinners, antiplatelet drugs, selective serotonin reuptake inhibitor (SSRI) antidepressants, and serotonin norepinephrine reuptake inhibitor (SNRI) antidepressants. Patients who take a combination of one of these drugs with diclofenac will be closely monitored for signs of bleeding. 
  • Diclofenac can interact with ACE inhibitors, angiotensin receptor blockers, or beta-blockers. These drugs may not work as well to control blood pressure when taken with an NSAID like diclofenac. In some patients, this combination can worsen kidney function or cause kidney failure. This includes patients who are older adults, volume-depleted (including those who take diuretics), or who have kidney problems. If these drugs are used together, depending on the risk factors, the healthcare professional will monitor blood pressure and kidney function on a regular basis, and ensure the patient is adequately hydrated. 

This is not a full list of drug interactions and others may occur. Consult your healthcare professional for more information about drug interactions with diclofenac.

How to avoid diclofenac side effects

  1. Before taking diclofenac, review your medical history, family history, allergies to medications, and medication list with your healthcare provider. This will ensure that diclofenac is safe for you to take. Only take diclofenac if approved by your healthcare provider. Do not take someone else’s diclofenac, even if they have the same symptoms, because it may not be safe for you. In the same regard, do not share your diclofenac with others, because it may not be safe for them.
  2. Ask your healthcare professional what side effects to expect and what to do if you experience them. Carefully read the prescription label, patient information leaflet, and medication guide. Consult your healthcare provider or pharmacist if you have any questions or concerns. 
  3. Take diclofenac exactly as directed. Do not take more than prescribed, and do not take diclofenac for longer than prescribed. Diclofenac should be taken at the lowest effective dose for the shortest time to avoid complications, so follow your doctor’s directions closely.
  4. Take diclofenac with food. This may decrease the chance of stomach upset. Diclofenac tablets are delayed-release or extended-release and should be swallowed whole. Do not chew, break, or crush diclofenac tablets. 
  5. While taking diclofenac, avoid alcohol and caffeine. Do not start any new medications—including OTC medications—unless approved by your healthcare provider or pharmacist. Some OTC medications contain NSAIDs, and taking diclofenac with other NSAIDs can increase the risk of serious side effects.

How to treat side effects of diclofenac

Report side effects to your prescriber. It is best to report concerning side effects right away (or seek emergency treatment if needed) rather than wait because serious side effects can occur. 

For mild side effects, you can often treat them or use non-medicinal methods until your body adjusts to the medicine. For example, if you experience a headache, you can take Tylenol (acetaminophen)—avoid OTC medications that contain an NSAID such as Advil. Check with your pharmacist if you need help selecting an OTC medicine. Resting in a cool, dark, quiet room and drinking plenty of fluids may help, too. 

Another example is a mild upset stomach. You can take diclofenac with food to lessen the chance of an upset stomach. If you feel nauseous, you can try eating bland foods as well as avoiding foods that are fried or spicy. 

If you experience the following symptoms, call your doctor right away:

  • Skin rash (even a mild rash)
  • Flulike symptoms
  • Swelling, fast weight gain, shortness of breath (these could signal heart problems)
  • Little or no urination, painful/difficult urination, tiredness, shortness of breath, swelling in the arms/legs (these could be symptoms of kidney problems)
  • Nausea, diarrhea, stomach pain, tiredness, itching, dark urine, clay-colored stools, yellowing of the skin or whites of the eyes (these could be symptoms of liver problems)
  • Bloody or tarry stools, coughing up blood or vomit that has a coffee ground appearance (these symptoms could signal internal bleeding)

Other symptoms can be more severe and require emergency medical attention. These may include:

  • Allergic reaction: hives, difficulty breathing, swelling of the face or throat
  • Skin reaction: fever, sore throat, burning eyes, skin pain, red or purple rash, blistering or peeling skin
  • Serious drug reaction: rash, fever, swollen glands, muscle pain, weakness, bruising, yellowing of the skin or whites of the eyes

Signs of a heart attack or stroke: chest pain that spreads to the jaw or shoulder, numbness/weakness on one side of the body, shortness of breath, slurred speech

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