Mefenamic acid: Uses, Side Effects & Safety

What it is and what it's used for

Mefenamic acid is a pain-relieving and anti-inflammatory medicine belonging to the NSAID (non-steroidal anti-inflammatory drug) family, in a subgroup known as the fenamates. It is best known for relieving period pain (primary dysmenorrhoea) — the cramping pain many women and girls experience during menstruation. It is also used for short-term relief of mild to moderate pain such as headache, dental pain, muscle pain, and pain after minor injury, and to reduce inflammation.

In India, mefenamic acid is generally a prescription medicine (Schedule H) and should be taken on a doctor's advice. It is meant for short courses — for example, a few days during a period — not for daily, long-term pain relief. Combination products that pair mefenamic acid with paracetamol or with dicyclomine (for stomach cramps) are also sold in India, but they are different products and should not be confused with plain mefenamic acid.

How it works (simple language)

Mefenamic acid works by blocking the body's production of substances called prostaglandins, which are chemicals that cause pain, cramping, swelling, and inflammation. During menstruation, the uterus produces extra prostaglandins, which make it contract strongly and cause cramp pain; by lowering these chemicals, mefenamic acid eases the cramps as well as other pain and inflammation. It also has a mild fever-reducing effect, though it is not normally used just for fever.

Dosage forms available in India (general info only)

Mefenamic acid is commonly available in India as 250 mg and 500 mg tablets, and as a suspension for children and others who cannot swallow tablets. A well-known Indian brand name is Meftal (Blue Cross), though brands vary by pharmacy. Combination brands such as Meftal Spas (mefenamic acid with dicyclomine) are also widely sold, but they contain an extra active ingredient, so always check the pack to see exactly which product you have.

Never decide the dose yourself from this article. Always follow your doctor's prescription or the directions on the pack, and check with your pharmacist if you are unsure — especially for children, where the dose depends on the child's weight and age.

Side effects

Common: Stomach pain, nausea, vomiting, diarrhoea, constipation, heartburn, indigestion, headache, dizziness, and drowsiness.

Serious — seek medical care: Stomach bleeding (black stools, vomiting blood or material that looks like coffee grounds), severe stomach pain, signs of kidney problems (very little urine, swelling of the legs or face), signs of liver problems (yellowing of the skin or eyes, dark urine, unusual tiredness), signs of a heart problem (chest pain, shortness of breath), severe skin rash or peeling, allergic reactions (rash, swelling of the face or lips, difficulty breathing), and unusual bruising or bleeding. Seek emergency care immediately if any of these occur.

Precautions and warnings

• Short courses only: Mefenamic acid is meant for a few days at a time. Longer use greatly increases the risk of stomach bleeding, kidney damage, and heart problems.
• Stomach and gut risk: Avoid it if you have active stomach ulcers or stomach bleeding, and be cautious if you have a history of ulcers or take blood thinners, steroids, or other NSAIDs at the same time.
• Kidney risk: It can harm the kidneys, especially in older adults, people who are dehydrated, and those with existing kidney or heart disease. Drink enough fluids unless your doctor has told you to restrict fluids.
• Heart and blood pressure: Like other NSAIDs, it may raise blood pressure and increase the risk of heart attack or stroke, particularly with higher doses or longer use. People with heart disease should use it only on a doctor's advice.
• Bleeding risk: It can increase bleeding, so tell your doctor before any surgery or dental procedure, and avoid it if you have a bleeding disorder.
• Asthma warning: People with asthma that is worsened by aspirin or other NSAIDs should avoid mefenamic acid, as it can trigger breathing difficulty.
• Alcohol: Avoid alcohol while taking it, as it increases the risk of stomach irritation and bleeding.

Interactions (general)

Mefenamic acid can interact with blood thinners (such as warfarin), other NSAIDs, aspirin, steroids, some blood pressure medicines (ACE inhibitors, diuretics), lithium, and methotrexate. Taking it together with other NSAIDs or steroids raises the risk of stomach bleeding. Always tell your doctor about ALL medicines you take, including herbal and ayurvedic products, and avoid alcohol during treatment.

Pregnancy and breastfeeding (general guidance)

Mefenamic acid should be avoided in pregnancy, especially in the third trimester, as it may harm the unborn baby and affect labour. It is generally not recommended while breastfeeding either. If you are pregnant, planning pregnancy, or breastfeeding, consult your doctor first before taking this medicine.

Storage

Store at room temperature, away from moisture and direct sunlight. Keep out of reach of children. Do not use after the expiry date printed on the pack, and dispose of expired tablets safely rather than flushing them down the drain.

When to see a doctor

See a doctor if: your period pain does not improve within a couple of days, your pain keeps coming back every month and is severe, you develop stomach pain, black stools, vomiting blood, swelling, reduced urination, or a rash. Seek emergency care immediately for chest pain, shortness of breath, severe stomach pain, signs of an allergic reaction, or uncontrolled bleeding.

FAQs

1. Is mefenamic acid good for period pain?

Yes, period pain is one of the main uses of mefenamic acid, and it is often chosen for this purpose because it targets the prostaglandins that cause menstrual cramps. It is usually taken for just a few days during the period, starting when the pain begins or shortly before, as advised by your doctor. If your period pain is very severe every month, talk to your doctor rather than simply repeating the medicine, as there may be an underlying cause to check.

2. Can I take mefenamic acid on an empty stomach?

It is usually best taken with food or milk to reduce stomach irritation, but always follow the directions your doctor or pharmacist gives you. If you notice stomach pain, heartburn, or nausea, tell your doctor rather than continuing on your own.

3. Is mefenamic acid the same as Meftal Spas?

No. Plain mefenamic acid (for example, Meftal) contains only mefenamic acid, while Meftal Spas is a combination product that also contains dicyclomine, which relaxes stomach and gut cramps. The two products are used for different kinds of cramp pain, so always check the pack and take only the product your doctor prescribed.

4. Can children take mefenamic acid?

Mefenamic acid is available as a suspension for children, but children should take it only on a doctor's advice, with the dose worked out from the child's weight and age. Never give a child an adult tablet or guess the dose, and seek medical advice if a child has a fever, stomach pain, or vomiting while taking it.