Adult: 200 mg as a single dose at the onset of symptoms, may repeat after 1-2 hours, if necessary.
Administration
Tolfenamic acid Should be taken with food.
Contraindications
Hypersensitivity. Active or history of recurrent peptic ulcer, current or history of gastrointestinal bleed or perforation associated with previous NSAID treatment, history of asthma, urticaria, or other allergic-type reactions following intake of aspirin or other NSAIDs; severe heart failure. Severe renal and hepatic impairment. Pregnancy (3rd trimester).
Special Precautions
Patient with hypertension, oedema, recent MI, mild to moderate CHF, ischaemic heart disease; history of gastrointestinal disorders (e.g. ulcerative colitis, Crohn's disease); other forms of asthma; porphyria, peripheral arterial disease, connective tissue disorder, cerebrovascular disease, coagulation defects, risk factors for CV events. Dehydrated patients. Not recommended for the treatment of perioperative pain in CABG setting. Mild to moderate renal and hepatic impairment. Elderly. Pregnancy (1st and 2nd trimester) and lactation.
Adverse Reactions
Significant: Sodium and fluid retention, CNS effects (e.g. drowsiness, dizziness, blurred vision), decreased platelet adhesion and aggregation, prolonged bleeding time, reduced prostaglandin synthesis, decreased female fertility, precipitation of renal failure, elevated transaminase, jaundice. Rarely, severe blood dyscrasias (e.g. agranulocytosis, thrombocytopenia, aplastic anaemia). Blood and lymphatic system disorders: Neutropenia, haemolytic anaemia. Cardiac disorders: Cardiac failure. Ear and labyrinth disorders: Tinnitus, vertigo. Gastrointestinal disorders: Nausea, vomiting, diarrhoea, flatulence, constipation, dyspepsia, abdominal pain, melaena, haematemesis, ulcerative stomatitis, exacerbation of colitis and Crohn's disease. General disorders and administration site conditions: Oedema, fatigue. Immune system disorders: Hypersensitivity. Nervous system disorders: Headache, hyperaesthesia, tremor. Psychiatric disorders: Depression, confusion, euphoria, hallucinations. Renal and urinary disorders: Dysuria (more common in males), urine discolouration. Respiratory, thoracic and mediastinal disorders: Asthma, pulmonary infiltration. Skin and subcutaneous tissue disorders: Photosensitivity. Vascular disorders: Hypertension. Potentially Fatal: Increased risk of serious CV thrombotic events including MI and stroke; gastrointestinal inflammation, ulceration, bleeding, and perforation; exfoliative dermatitis, Stevens-Johnson syndrome, toxic epidermal necrolysis; bronchospasm. Rarely, liver reactions (e.g. fulminant hepatitis).
Patient Counseling Information
This drug may cause drowsiness, dizziness, blurred vision, and other neurologic effects, if affected, do not drive or operate machinery.
Monitoring Parameters
Monitor CBC, kidney function (e.g. serum BUN, creatinine, urine output), liver function, and blood pressure; weight and oedema. Observe for bleeding, bruising, and gastrointestinal effects (e.g. abdominal pain, bleeding, dyspepsia).
Overdosage
Symptoms: Headache, nausea, vomiting, epigastric pain, gastrointestinal bleeding. Rarely, diarrhoea, disorientation, excitation, coma, drowsiness, dizziness, tinnitus, fainting. Occasionally, convulsions. In cases of significant poisoning, acute renal failure and liver injury may occur.
Management: Symptomatic and supportive treatment. Activated charcoal or gastric lavage (in adults) may be considered within 1 hour of ingesting a potentially toxic or life-threatening overdose. Maintain adequate urine output. Closely monitor renal and hepatic function. Observe patients for at least 4 hours after ingestion of toxic amounts. Treat frequent or prolonged seizures with IV diazepam. Additional measures should be determined by the patient's clinical status.
Drug Interactions
May decrease therapeutic effect of antihypertensive agents and diuretics. May increase the risk of nephrotoxicity with diuretics, ciclosporin, and tacrolimus. May exacerbate cardiac failure, decrease GFR, and increase serum glycoside levels with cardiac glycosides. May increase the effect of lithium. May reduce methotrexate elimination. May decrease the effect of mifepristone. Increased risk of gastrointestinal ulceration or bleeding with corticosteroids. May enhance the effects of anticoagulants (e.g. warfarin). Increased risk of gastrointestinal bleeding with antiplatelet agents and SSRIs. Increased risk of haematological toxicity with zidovudine.
Action
Description: Overview: Tolfenamic acid, an anthranilic acid derivative related to mefenamic acid, is a non-steroidal anti-inflammatory drug (NSAID). Mechanism of Action: Tolfenamic acid inhibits prostaglandin biosynthesis and leukotriene formation. It has antipyretic, analgesic, and anti-inflammatory properties. Pharmacokinetics: Absorption: Rapidly and completely absorbed from the gastrointestinal tract. Bioavailability: 85%. Time to peak plasma concentration: 60-90 minutes. Distribution: Enters breast milk. Plasma protein binding: 99%. Metabolism: Metabolised in the liver; undergoes conjugation with glucuronic acid. Excretion: Via urine (90% as conjugate); faeces (10%). Elimination half-life: Approx 2 hours.
Chemical Structure
Tolfenamic acid Source: National Center for Biotechnology Information. PubChem Compound Summary for CID 610479, Tolfenamic Acid. https://pubchem.ncbi.nlm.nih.gov/compound/Tolfenamic-Acid. Accessed Jan. 28, 2026.
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