What it's for (Indications)
- Mefenamic acid is indicated for the treatment of mild to moderate pain, including headaches, menstrual cramps (primary dysmenorrhea), migraines, pain associated with rheumatoid arthritis, backache, dental pain, post-operative pain, muscular pain, post-partum pain, and osteoarthritis.
- It works by helping to lower prostaglandins in the body, which can relieve menstrual pain and reduce menstrual bleeding.
Dosage Information
| Type | Guideline |
|---|---|
| Standard | For adults and adolescents 14 years of age and older, the recommended initial oral dose is 500 mg, followed by 250 mg every 6 hours as needed. For the treatment of primary dysmenorrhea, the dosage is also 500 mg orally as an initial dose, followed by 250 mg every 6 hours. It is advised to take the dose at the beginning of pain. The use of mefenamic acid is generally discouraged for over 7 days. Always use the lowest effective dose for the shortest duration. Dosage may vary based on individual patient condition, age, and response to treatment; always consult a doctor for precise dosing instructions. |
Safety & Warnings
Common Side Effects
- Common side effects include gastrointestinal disturbances such as stomach upset, gastric intolerance, flatulence, nausea, vomiting, and taste disturbances.
- More serious gastrointestinal effects can include ulcers, bleeding, and perforation.
- Other side effects include skin rash (which may be severe, such as Stevens-Johnson Syndrome), renal impairment (including renal toxicity and hyperkalemia), rise in liver enzymes (including hepatotoxicity and abnormal liver function tests), dizziness, headache, hypertension, heart failure, edema, cardiovascular thrombotic events (e.
- g.
- , chest pain), severe dizziness, trouble breathing, weakness on one side of the body, anaphylactic reactions, and hematologic toxicity (e.
- g.
- , anemia).
- If severe symptoms like chest pain, severe dizziness, trouble breathing, or weakness on one side of the body occur, discontinue use and seek immediate medical attention.
Serious Warnings
- Black Box Warning: WARNING: RISK OF SERIOUS CARDIOVASCULAR and GASTROINTESTINAL EVENTS. Nonsteroidal anti-inflammatory drugs (NSAIDs) cause an increased risk of serious cardiovascular thrombotic events, including myocardial infarction and stroke, which can be fatal. This risk may occur early in treatment and may increase with duration of use. Mefenamic acid is contraindicated in the setting of coronary artery bypass graft (CABG) surgery.
- Use the lowest effective dose for the shortest duration consistent with individual patient treatment goals.
- Mefenamic acid may cause dizziness; therefore, tasks requiring alertness, such as driving or operating machinery, should be avoided immediately after taking this medicine.
- Caution is advised in patients with a history of heart disease (including family history), asthma, allergic reactions, stomach and bleeding disorders, and diabetes.
- Elderly patients should be particularly cautious.
- Patients with severe kidney or liver impairment should avoid this medication; all patients using mefenamic acid should be monitored for renal and hepatic toxicity.
- Alcohol consumption should be avoided or discussed with a healthcare provider.
- Do not take mefenamic acid with antacids unless prescribed by a doctor, and avoid concomitant use with other NSAIDs (e.
- g.
- , ibuprofen, celecoxib) due to an increased risk of gastrointestinal bleeding.
- Mefenamic acid has been associated with serious cardiovascular thrombotic events (myocardial infarction, stroke) and serious gastrointestinal bleeding, ulceration, and perforation, which can be fatal.
- It can also lead to hepatotoxicity, hypertension, heart failure, edema, renal toxicity (including hyperkalemia), anaphylactic reactions, serious skin reactions (e.
- g.
- , Stevens-Johnson Syndrome), and hematologic toxicity.
- During pregnancy and lactation, mefenamic acid should only be used if the potential benefits outweigh the potential risks, and after consulting a doctor, as definitive safety data in these populations are undetermined.
How it Works (Mechanism of Action)
Mefenamic acid is a Non-Steroidal Anti-Inflammatory Drug (NSAID) with analgesic, anti-inflammatory, and antipyretic properties. Its mechanism of action involves the inhibition of cyclooxygenase (COX-1 and COX-2) enzymes, leading to a potent inhibition of prostaglandin synthesis. Prostaglandins are mediators of pain and inflammation; by decreasing their production, mefenamic acid reduces their effects in peripheral tissues.