Fenac - Interactions | Adverse effects | Use

This article was medically reviewed by M.Pharm, Marko Tanaskovic on August 12, 2018. To read more about an author, click here.

Fenac is a medicine available in Australia and contains Diclofenac as an active pharmaceutical ingredient. It belongs to the group of non-steroidal anti-inflammatory drugs (NSAIDs). It is used to relieve pain and inflammatory processes in the following diseases:

  • Rheumatoid arthritis - a chronic autoimmune disease in characterized by swelling of the joints, joint stiffness and loss of joint function
  • Osteoarthritis - a disease characterized by wearing of protective cartilage on the ends of bones and most often affects the wrists, hips and knees.
  • Various types of mild to moderate pain (headache, dental pain, shoulder pain, back pain, soft tissue injuries such as sprains and strains)
  • Inflammation of the tendon (tendinitis)
  • Inflammation of the tendons and their sheaths (tenosynovitis)
  • Inflammation of fluid-filled sac which is located inside the joints (i.e. Bursitis)
  • Mild to moderate postoperative pain


Fenac is contraindicated in the following conditions:

  • If you have or have ever had bleeding in the stomach or intestines caused by non-steroidal anti-inflammatory drugs
  • If you have or have ever had recurrent ulcer
  • If you are pregnant or breastfeeding
  • If you have severe kidney impairment
  • If you have severe liver damage
  • If you suffer from heart disease
  • If you are allergic to any drugs from the group of NSAIDs


Extra precaution is required in the following situations:

  • If you have a porphyrin metabolism disorder (porphyria)
  • If you have a disease of the circulatory system. This drug can inhibit platelet aggregation therefore may affect the coagulation of blood.
  • If you have had a stroke or heart attack
  • If you suffer from systemic lupus erythematosus
  • If you have high blood pressure
  • If you are a smoker
  • If you are diabetic
  • If you have more than 60 years

Fenac, pregnancy and breastfeeding

AU TGA classifies this drug to the group C, since clinical studies in animals have shown that the use of this drug during pregnancy may cause premature closure of the ductus arteriousus as well as to postpone labor. Testing on animals has shown that this drug can inhibit platelet aggregation and cause kidney damage in newborns whose mothers took this medication during pregnancy. For these reasons, the use of Fenac during pregnancy must be avoided.

This drug has a negative impact on fertility in women and should be avoided in women who are trying to become pregnant.

Its use during breastfeeding should be avoided due to limited data on safety.

Dosage instructions

The usual dose in adults is 100 mg once daily. Swallow the tablet whole with plenty of liquid. It is recommended to swallow the tablet during or immediately after a meal, in order to reduce the risk of gastrointestinal side effects.

The maximum daily dose is 200 mg.

It is recommended to use smaller doses (50 mg daily) in patients above the age of 60.


Fenac should not be administered concurrently with the following drugs:

  • Medications with a positive inotropic effect used for the treatment of heart failure (e.g. digoxin)
  • Anti-coagulants (e.g. warfarin, heparin, and acenocoumarol)
  • Water pills (diuretics)
  • Drugs that increase the plasma levels of potassium (spironolactone, triamterene, amiloride, trimethoprim, cyclosporin, etc.)
  • ACE inhibitors (ramipril, enalapril, lisinopril, cilazapril, captopril and others)
  • Beta blockers (propranolol, bisoprolol, carvedilol, atenolol, etc.)
  • Anxiolytics and antidepressants from the group of selective serotonin reuptake inhibitors (sertraline, fluoxetine, paroxetine and fluvoxamine)
  • Fluoroquinolones (ciprofloxacin, ofloxacin and norfloxacin)
  • Cholesterol-absorption inhibitors (e.g. cholestyramine and colestipol)
  • Drugs used for the treatment of diabetes mellitus type 2

Adverse effects

Possible adverse effects of Fenac are given in the table below:

Frequently (occurring in 1-10% of patients) Rare (occurring in 0.1-0.01% of patients) Very rare (occurring in less than 0.01% of patients) Incidence not known
Slightly increased levels of AST and ALT in blood Fluid retention Paraesthesia Optical neuritis
Vertigo Allergic reactions (including anaphylactic shock) Thrombocytopenia and inhibition of platelet aggregation Weakness
Headache Hepatic impairment Vision impairment (double vision or blurred vision) Sensibility disorders
Dizziness Gastric ulcer including vomiting of blood and the presence of blood in stool Hepatic necrosis Confusion
Gastrointestinal adverse reactions (diarrhea, abdominal pain, vomiting, loss of appetite and gases) Difficulty breathing Pneumonitis Hallucinations


  1. PIL

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