8 Diclofenac Side Effects to Be Aware of: Nausea Swelling, and More

Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) that’s used to treat pain and inflammation. It comes in many dosage forms, such as oral tablets (Cataflam) or capsules (Zipsor), oral or topical solutions, and an oral powder (Cambia). It’s also available as a topical gel, topical patch (Flector, Licart), and eye drops.

Most forms of diclofenac are available by prescription only. But a topical gel (Voltaren Gel) is available over the counter (OTC). Each dosage form has a unique dosage. And each carries a risk for certain side effects. For instance, heartburn and nausea are common with oral forms of diclofenac. But what other side effects are possible?

Good to know: Topical forms of diclofenac have a lower risk of side effects compared with oral forms. This is because the body absorbs less medication through the skin or eyes compared with taking it by mouth. Here, we focus primarily on side effects related to oral diclofenac.

Diclofenac side effects at a glance

Many common diclofenac side effects are digestive-related. But other side effects are possible. Mild side effects can often be managed at home, while serious side effects may require medical care.

Common or mild diclofenac side effects include:

• Nausea

• Vomiting

• Heartburn

• Headache

• Stomach pain or upset

• Constipation

• Diarrhea

• Dizziness

• Itching

• Swelling

• Tinnitus (ringing in the ears)

• Increased blood pressure

• Mildly elevated potassium levels

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Rare but serious diclofenac risks and side effects include:

• Higher risk of bleeding

• Severely elevated potassium levels

• Liver damage

• Kidney damage

• Severe skin rashes

• Allergic reactions

• Worsening of heart failure

• Low red blood cell counts (anemia)

This medication also has a few boxed warnings. This is the FDA’s strictest warning for medications. While rare, these side effects can be life-threatening. Diclofenac has the following boxed warnings:

• Heart attack

• Stroke

• Blood clots

• Higher risk of death for people who recently had a heart attack or heart bypass surgery

• Gastrointestinal bleeding, ulcers, and tears

This isn’t a full list of all possible diclofenac side effects. Always contact your healthcare team about unusual or severe side effects — even if they’re not listed here. Below, we detail eight diclofenac side effects you should know about.

1. Stomach upset

NSAIDs are known for causing digestive side effects. These include heartburn, nausea, and diarrhea. Digestive side effects can range from mild to serious.

Managing mild stomach side effects can be as simple as taking your diclofenac doses with food. Having something in your stomach might reduce feelings of stomach upset.

EXPERT PICKS: WHAT TO READ NEXT

• People who shouldn’t take diclofenac: Learn which people should avoid nonsteroidal anti-inflammatory drugs (NSAIDs) such as diclofenac.

• Recommended dosages: Read about the typical diclofenac dosages recommended for each version of the medication.

• What to avoid: Pharmacists review notable diclofenac interactions that can raise your risk of certain side effects.

While taking diclofenac, it’s also best to avoid drinking alcohol. This combination can worsen digestive side effects. It also raises your risk of serious stomach issues, such as bleeding or ulcers (more on this later).

If you have stomach pain that becomes bothersome or won’t go away, let your healthcare team know. This can be a symptom of potentially serious problems. In that case, seek medical help right away.

2. Headache

Sometimes, diclofenac is used to treat headaches. So it may seem strange that headaches are a possible side effect. But taking too much diclofenac (or taking it too frequently) can cause a rebound headache.

Rebound headaches can happen if you take diclofenac to treat headaches frequently or at higher doses than recommended. You may notice that you have more headaches than before (possibly every day). Your headaches may also return after diclofenac wears off.

Rebound headaches are usually treated by stopping the medication causing them. But speak to your healthcare team before stopping diclofenac. They may want to make adjustments to other headache treatments you may be using. This may include starting or changing medications that help prevent headaches.

3. Tinnitus (ringing in the ears)

Several medications can cause tinnitus (ringing in the ears), including NSAIDs such as diclofenac. In one study, people who took NSAIDs several times a week were more likely to have tinnitus than those who only took them occasionally.

Tinnitus from diclofenac often goes away if you stop taking it. But tinnitus can have many possible causes. So it may not always be related to diclofenac.

If you have tinnitus, you may be able to wait a day or two to see if the symptoms resolve on their own. But if they aren’t going away or are getting worse, check with your healthcare team. They may recommend changing your medication regimen or getting a hearing evaluation.

4. Swelling

While taking NSAIDs such as diclofenac, your body tends to hold on to more fluid. This can cause fluid buildup, leading to swelling, particularly in your legs and ankles.

In many cases, swelling from diclofenac is mild and resolves on its own. But if you have a condition such as heart failure or kidney disease, swelling can make your condition worse.

If you experience sudden weight gain and swelling, talk to your healthcare team for next steps. These are possible signs of fluid retention. Depending on your situation, they may suggest stopping diclofenac.

5. High blood pressure

Diclofenac can raise your blood pressure, partially due to fluid buildup, as discussed above. Typically, this increase is small. And your blood pressure should return to normal if you stop taking diclofenac. Diclofenac also seems to have less of an effect on blood pressure than other NSAIDs.

This side effect can be more of an issue if you already have hypertension (high blood pressure). And your prescriber may ask you to check your blood pressure at home if you’re taking diclofenac regularly.

6. Kidney damage

Diclofenac can affect how well your kidneys work. It can temporarily reduce blood flow to the kidneys. For most people, this isn’t a problem. But people with kidney disease may be more sensitive to these effects.

Your risk for kidney damage may also be higher if you also take certain other medications. These include blood pressure medications, such as angiotensin converting enzyme (ACE) inhibitors, and/or diuretics (“water pills”).

Your prescriber may ask you to avoid diclofenac if you have kidney problems. They’ll likely also routinely check your kidney function if you take diclofenac regularly.

7. Stomach bleeding or ulcers

Diclofenac has a boxed warning for gastrointestinal (GI) bleeding, tears, and ulcers. Taking higher doses for longer periods of time may raise your risk for this side effect.

You’re also more likely to have bleeding or ulcers if you:

• Have a history of stomach bleeding or ulcers

• Are older than 60

• Drink more than three alcoholic beverages per day

• Take blood thinners, such as warfarin (Coumadin, Jantoven)

• Take corticosteroids (“steroids”), such as prednisone

While you’re taking diclofenac, your prescriber may also recommend a medication to protect your stomach. This could be an H2 blocker, such as famotidine (Pepcid AC), or a proton pump inhibitor, such as omeprazole (Prilosec).

8. Heart problems

As mentioned above, fluid buildup caused by diclofenac may worsen heart failure. But other serious heart problems are also possible. NSAIDs can raise the risk of unwanted blood clots, which can lead to a heart attack or stroke. This is a boxed warning for diclofenac.

People who have recently had a heart attack or heart bypass surgery should avoid diclofenac and other NSAIDs. These groups of people have a higher risk of fatal heart complications when taking NSAIDs. If this applies to you, discuss with your healthcare team if or when you can safely take these medications again.

Taking diclofenac at the lowest dose needed for the shortest time possible helps lower the risk of serious heart-related side effects. But some people may need to take higher doses or need to take it long term. Your healthcare team can help you weigh your personal risks and benefits of long-term diclofenac treatment.

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Written by:

Austin Ulrich, PharmD, BCACP

Austin Ulrich, PharmD, BCACP, is a board-certified ambulatory care clinical pharmacist. In his early career, he provided direct patient care in a variety of settings, including hospital and community pharmacies, and in a primary care clinic as a clinical pharmacist.

Edited by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Reviewed by:

Joshua Murdock, PharmD, BCBBS

Joshua Murdock, PharmD, BCBBS, is a licensed pharmacist in Arizona, Colorado, and Rhode Island. He has worked in the pharmacy industry for more than 10 years and currently serves as a pharmacy editor for GoodRx.

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