Along with their useful effects, most medicines can cause unwanted side effects although not everyone experiences them. The unwanted effects often improve as your body adjusts to the new medicine, but please speak with your doctor or pharmacist if they continue or become troublesome. You will find a full list of possible side effects in the Patient Information Leaflet (PIL) supplied with your medicine.

Stop taking Mefenamic Acid if you experience any of the following reactions, and seek medical help immediately:

Allergic Reactions:

• Difficulty in swallowing or breathing, swelling of the face, lips, throat or tongue
• Severe skin itching with a red rash or raised bumps
• Blistering of the eyes, mouth, or genital area, with patch areas of peeling skin or rash

Other Reactions:

• Diarrhoea
• Passing blood in your faeces (stools/motions), or tar-like black faeces
• Vomiting blood or dark particles which look like coffee grounds

Seek immediate medical attention if you have any of the below symptoms:

• Indigestion or heartburn, pain in your stomach or abdominal area, feeling sick (nausea), vomiting
• Unusual bleeding or bruising, such as nose bleeds, pinpoint red spots on the skin, purple bruise-like rash in the mouth or on the skin
• Feeling tired, breathless, or looking pale, which may be signs of anaemia
• Fever, sore throat, mouth ulcers, repeated or persistent infections, which may be signs of low levels of white blood cells
• Seizures (fits)
• Headache, nausea, vomiting, tiredness, or muscle cramps which may be signs of low sodium levels
• Sudden headache, stiff neck, fever, sensitivity to bright lights, drowsiness, muscle pain, with or without rash
• Fever, rash, nausea, aches or pains, changes in amount of urine passed, passing red urine, passing urine at night, which may be signs of changes in your kidneys
• Sudden loss of or blurred vision, loss of colour vision, eye pain which worsens on movement of the eye
• Headache, especially on waking in the morning, which may be due to high blood pressure
• Pain behind the ribs which spreads towards the back and is worse when lying down, nausea, vomiting, fever, which may be due to inflammation of your pancreas
• Yellowing of the eyes or skin, pale faeces and dark urine, unexplained and persistent nausea, stomach problems, appetite loss, or unusual tiredness, which may be due to changes in your liver

Tell your doctor if you get any of the following side effects:

• Vertigo (head spinning)
• Fatty faeces
• Sweating
• Palpitations (rapid heartbeat)
• Mental confusion
• Appetite loss
• Constipation or bloating
• Blurred vision, eye irritation
• Feeling ill (malaise)
• Tinnitus (buzzing or ringing in the ears)
• Tingling or numbness of the hands or feet
• If you have diabetes, sudden and poor blood sugar control – your doctor or pharmacist can help measure your blood sugar levels
• Asthma, or asthma which may be worse than usual
• Swelling of your hands or around your ankles/feet
• Mouth pain, which may show as pain or ulcers of the tongue, cheeks, lips, throat or gums
• Dizziness, drowsiness, feeling lethargic and tired
• Symptoms of low blood pressure, e.g. light-headedness
• Reactions to the sun such as red, painful, or swollen skin. Whilst taking Mefenamic Acid, do not use a sun bed, sunbathe, or expose your skin to artificial ultraviolet (UV) light
• Depression
• Inability to sleep
• Hallucinations
• Nervousness
• Ear pain