Mefenamic Acid Dosage

Medically reviewed by Drugs.com. Last updated on May 20, 2022.

Usual Adult Dose for Pain

Initial dose: 500 mg orally once
Following initial dose: 250 mg orally every 6 hours as needed
Duration of therapy: Usually not to exceed 1 week

Use: For the relief of acute pain

Usual Adult Dose for Dysmenorrhea

Initial dose: 500 mg orally once
Following initial dose: 250 mg orally every 6 hours as needed
Duration of therapy: 2 to 3 days

Comments:

• Treatment should begin at the onset of bleeding and associated symptoms.

Use: For the treatment of primary dysmenorrhea

Usual Pediatric Dose for Pain

14 years or older:

• Initial dose: 500 mg orally once
• Following initial dose: 250 mg orally every 6 hours as needed
• Duration of therapy: Usually not to exceed 1 week

Use: For the relief of acute pain

Usual Pediatric Dose for Dysmenorrhea

14 years or older:

• Initial dose: 500 mg orally once
• Following initial dose: 250 mg orally every 6 hours as needed
• Duration of therapy: 2 to 3 days

Comments:

• Treatment should begin at the onset of bleeding and associated symptoms.

Use: For the treatment of primary dysmenorrhea

Renal Dose Adjustments

Preexisting renal disease: Contraindicated

Liver Dose Adjustments

• Dose adjustments may be required in patients with liver dysfunction, however, no specific guidelines have been suggested; caution is recommended.

• Patients who have an abnormal liver test or who develop signs or symptoms of liver dysfunction should be evaluated for hepatic dysfunction.
• If liver disease develops or if systemic manifestations such as eosinophilia or rash occur, this drug should be discontinued.

Dose Adjustments

Elderly: Consider lower doses due to the increased risk of concomitant disease states and the increased risk of adverse events. Clinical studies did not include a sufficient number of patients aged 65 years or older to determine if these patients respond differently.

Precautions

US BOXED WARNINGS: RISK OF SERIOUS CARDIOVASCULAR AND GASTROINTESTINAL EVENTS:

• Nonsteroidal anti-inflammatory drugs (NSAIDs) cause an increased risk of serious cardiovascular (CV) thrombotic events, myocardial infarction and stroke, which can be fatal. This risk may occur early in treatment and may increase with duration of use.
• This drug is contraindicated in the setting of coronary artery bypass graft (CABG) surgery.
• NSAIDs cause an increased risk of serious gastrointestinal (GI) adverse events including bleeding, ulceration, and perforation of the stomach or intestines, which can be fatal. These events can occur at any time during use and without warning symptoms. Elderly patients and patients with a prior history of peptic ulcer disease and/or GI bleeding are at a greater risk for serious GI events.

CONTRAINDICATIONS:

• Hypersensitivity to any of the ingredients
• History of asthma, urticaria, or other allergic-type reactions after aspirin or other NSAIDs; severe, sometimes fatal anaphylactic reactions have been reported in such patients.
• In the setting of coronary artery bypass graft (CABG) surgery

Safety and efficacy have not been established in patients younger than 14 years.

Consult WARNINGS section for additional precautions.

Dialysis

Data not available

Other Comments

Administration advice:

• Take orally with food or milk.

General:

• Prior to initiating treatment, the potential benefits and risks of this drug should be weighed against other treatment options.
• The lowest effective dose for the shortest duration consistent with individual patient treatment goals should be used.
• There is an increased risk of heart attack, heart failure, and stroke when taking nonsteroidal anti-inflammatory drugs (NSAIDs); these events may occur at any time during treatment and risk increases with long term use, a history of cardiovascular (CV) disease or risk factors for CV disease, and higher doses.

Monitoring:

• Cardiovascular: Monitor blood pressure closely during initiation and throughout course of therapy.
• Gastrointestinal: Monitor for signs/symptoms of gastrointestinal bleeding.
• Renal function: Monitor renal status, especially in patients with conditions where renal prostaglandins have a supportive role in the maintenance of renal perfusion.
• Monitor blood counts, renal, and hepatic function periodically for patients receiving long-term therapy.

Patient advice:

• Patients should seek medical advice for signs and symptoms of gastrointestinal events, adverse skin reactions, allergic reactions, hepatotoxicity, or unexplained weight gain or edema.
• Patients should seek medical attention immediately if signs/symptoms of cardiovascular events occur including, shortness of breath, slurred speech, chest pain, or weakness on one side of the body.
• Patients should talk to their health care provider if they are pregnant, planning to become pregnant, or breastfeeding; NSAIDs should not be used at 20 weeks or later in pregnancy unless specifically advised to do so by their health care professional.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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