Cataflam Side Effects: What to Expect and When to Call Your Doctor

Like all NSAIDs, Cataflam (diclofenac potassium) comes with a range of possible side effects — from minor stomach discomfort to rare but serious cardiovascular events. Understanding what to expect helps you use the medication safely and know when to seek medical attention.

FDA Boxed Warnings: The Most Important Risks

Cataflam carries two FDA boxed warnings — the most serious type of warning the FDA issues:

Cardiovascular risk: NSAIDs increase the risk of serious cardiovascular thrombotic events, including heart attack and stroke, which can be fatal. This risk may occur early in treatment and may increase with longer use or higher doses. People with existing heart disease are at higher risk.

Gastrointestinal risk: NSAIDs increase the risk of serious GI adverse events including bleeding, ulceration, and perforation of the stomach or intestines, which can be fatal. These events can occur without warning at any time during treatment.

Common Side Effects (Usually Manageable)

Most people taking Cataflam experience mild side effects that improve over time or can be managed. The most common include:

Nausea and stomach upset — take with food or milk to reduce this

Stomach pain or cramping

Diarrhea or constipation

Headache

Dizziness or drowsiness

Increased blood pressure — your doctor may monitor this with long-term use

Mild fluid retention (swelling in the legs)

Elevated liver enzymes — occurs in about 2-4% of patients on long-term diclofenac

Serious Side Effects: Call Your Doctor Right Away

Stop taking Cataflam and contact your doctor immediately if you experience any of the following:

Signs of GI bleeding: Black or tarry stools, vomiting blood or material that looks like coffee grounds, severe stomach pain

Signs of liver problems: Yellowing of the skin or eyes (jaundice), dark urine, severe fatigue, nausea, right upper abdominal pain

Signs of kidney problems: Decreased urination, unusual swelling, or symptoms of high potassium (muscle weakness, tingling, irregular heartbeat)

Skin rash of any kind: NSAIDs can cause rare but fatal skin reactions (Stevens-Johnson Syndrome, toxic epidermal necrolysis). Stop the medication immediately if any rash appears, no matter how mild.

Severe allergic reaction (DRESS): Fever, rash, swollen lymph nodes, organ involvement — requires immediate medical care

Emergency Symptoms: Call 911

Get emergency help immediately if you experience:

Chest pain, pressure, tightness, or pain spreading to jaw or shoulder (heart attack)

Sudden numbness or weakness on one side of the body, trouble speaking, or severe headache (stroke)

Difficulty breathing, throat tightening, severe allergic reaction (anaphylaxis)

Widespread skin blistering or peeling (Stevens-Johnson Syndrome)

How to Reduce Your Risk of Side Effects

You can significantly reduce your risk of Cataflam side effects by following these practices:

Use the lowest effective dose for the shortest time possible

Take with food, milk, or a full glass of water to minimize GI upset

Avoid alcohol — it increases GI bleeding risk

Don't take other NSAIDs (ibuprofen, naproxen, aspirin) at the same time

Tell your doctor about all medications you take, including OTC drugs and supplements

Get periodic blood tests for liver and kidney function if taking long-term

For a full review of medications that interact with Cataflam, see our Cataflam drug interactions guide.