Consumer medicine information

Fasigyn tablets



Brand name


Active ingredient





Consumer medicine information (CMI) leaflet

Please read this leaflet carefully before you start using Fasigyn tablets.

What is in this leaflet

This leaflet answers some common questions about Fasigyn. It does not contain all the available information.

It does not take the place of talking to your doctor or pharmacist.

All medicines have risks and benefits. Your doctor has weighed the risks of you taking Fasigyn against the benefits they expect it will have for you.

If you have any concerns about taking this medicine, ask your doctor or pharmacist.

Read this leaflet carefully before starting Fasigyn and keep it with your medicine. You may need to read it again.

What Fasigyn is used for

Fasigyn is used to

  • treat certain infections of the male and female genital systems, liver and bowel
  • prevent certain infections that may occur during surgery.

Fasigyn is an antibiotic, which belongs to a group of medicines called nitroimidazoles.

Fasigyn works by killing or stopping the growth of bacteria causing your infection.

Fasigyn will not work against viral infections such as colds or flu.

Your doctor, however, may prescribe Fasigyn for another purpose.

Ask your doctor if you have any questions about why Fasigyn has been prescribed for you.

This medicine is available only with a doctor's prescription.

Before you take Fasigyn

When you must not take it

Do not take Fasigyn if you are allergic to:

  • Fasigyn
  • any ingredients listed at the end of the leaflet
  • or related medicines such as Simplotan, Flagyl, Metrogyl and Metozine (not all brands given)

If you are not sure if you are allergic to any of the above, ask your doctor.

Symptoms of an allergic reaction include:

  • asthma, wheezing or shortness of breath
  • swelling of the face, lips or tongue which may lead to difficulty swallowing or breathing
  • hives, itching, skin rash or redness of skin
  • fainting, light-headedness

Do not take Fasigyn if you have a history of any blood disorder.

Do not take Fasigyn if you have any disease of the brain, spinal cord or nerves.

Do not take Fasigyn if you are pregnant or intend to become pregnant. Your doctor will discuss the risks and benefits of taking Fasigyn during pregnancy (pregnancy up to four months).

If you are a woman of child-bearing age, make sure you do not become pregnant while taking Fasigyn.

Do not take Fasigyn if you are breastfeeding. Like many other medicines, Fasigyn passes into breast milk and may harm your baby.

Do not breastfeed your baby while taking, and until at least three days after stopping Fasigyn.

If you are not sure whether you should be taking Fasigyn, talk to your doctor.

Do not take Fasigyn if the expiry date (EXP) or use by date printed on the pack has passed. If you take this medicine after this date, it may not work.

Do not take Fasigyn if the packaging is torn or shows signs of tampering. If this is the case, return it to your pharmacist.

If you are not sure whether you should start taking Fasigyn, talk to your doctor.

Before you start to take it

You must tell your doctor if:

  1. you have any allergies to:
  • any other medicines
  • any other substances, such as foods, preservatives or dyes
  1. you are pregnant or intend to become pregnant
Like most other medicines, Fasigyn is not recommended in pregnancy. However, your doctor will discuss the possible risks and benefits of taking Fasigyn during pregnancy.
  1. you are breastfeeding or plan to breast-feed
Like most other medicines, Fasigyn is not recommended in breast-feeding. However, your doctor will discuss the possible risks and benefits of taking Fasigyn during breast-feeding.
  1. you have or have had any other medical conditions, including any kidney problems
  2. you drink alcohol, even occasionally. Do not drink during and for 3 days after stopping treatment with Fasigyn.
If you drink alcohol with Fasigyn it may make you feel sick, vomit, have stomach cramps, headache or flushing.

If you have not told your doctor about any of the above, tell them before you are given Fasigyn.

Taking other medicines

Tell your doctor if you are taking any other medicines, including medicines you buy without a prescription from a pharmacy, supermarket or health food shop.

Some medicines may interfere with Fasigyn. These include:

  • warfarin or other medicines used to prevent blood clots

These medicines may be affected by Fasigyn or may affect how well it works.

Your doctor or pharmacist has more information on medicines to be careful with or avoid while taking Fasigyn.

Do not take medicines that contain alcohol (eg cough syrups) while using, or for three (3) days after stopping Fasigyn.

Talk to your doctor about the need for an additional method of contraception while taking Fasigyn. Some antibiotics may decrease the effectiveness of some birth control pills, although this has not been shown with Fasigyn.

How to take Fasigyn

Follow all directions given to you by your doctor or pharmacist carefully. They may differ from the information contained in this leaflet.

If you do not understand the instructions on the pack, ask your doctor or pharmacist for advice.

How much to take


Fasigyn is usually given as a single dose of four tablets, to be taken at the same time.

However, depending on your condition and how you react to the medicine, your doctor may ask you to take some other dose or take it for a longer time.


For children, the dose depends on body weight.

How long to take

Your doctor will tell you how long you need to keep taking Fasigyn.

In some cases, you may need to take Fasigyn for up to ten days.

How to take it

Swallow the tablets with liquid

When to take it

Take Fasigyn during or immediately after a meal. If taken on an empty stomach, it may cause stomach upset, nausea or vomiting.

If you forget to take it

If you are taking more than a single dose of Fasigyn and if it is almost time for your next dose, skip the dose you missed and take your next dose when you are meant to.

Otherwise, take it as soon as you remember, then go back to taking it as you would normally.

Do not try to make up for missed doses by taking more than one dose at a time. This may increase the chance of you getting an unwanted side effect.

If you are not sure what to do, check with your doctor or pharmacist.

If you have trouble remembering to take your Fasigyn, ask your pharmacist for some hints.

If you take too much (overdose)

Immediately telephone your doctor or Poisons Information Centre (telephone in Australia - 13 11 26) for advice, or go to Accident and Emergency (Casualty) at your nearest hospital if you think you or anyone else may have taken too much Fasigyn. Do this even if there are no signs of discomfort or poisoning. You may need urgent medical attention.

Keep telephone numbers of these places handy.

If you take too many tablets, you may get an upset stomach, diarrhoea or skin rashes.

While you are taking Fasigyn

Things you must do

If you become pregnant while taking Fasigyn, tell your doctor immediately.

If you get a sore, white mouth or tongue while taking, or soon after stopping Fasigyn, tell your doctor or pharmacist.

If you get vaginal itching, burning or a white discharge while taking, or soon after stopping Fasigyn, tell your doctor or pharmacist. This may mean you have a yeast infection called thrush. Sometimes use of Fasigyn allows yeast to grow and the above symptoms to occur. Fasigyn does not work against yeast.

If you are about to be started on any new medicines, tell your doctor or pharmacist that you are taking Fasigyn.

Tell all doctors, dentists and pharmacists who are treating you that you are taking Fasigyn.

Things you must not do

Do not give Fasigyn to anyone else, even if they have the same condition as you.

Do not use Fasigyn to treat any other medical complaints unless your doctor tells you to.

Side effects

Check with your doctor as soon as possible if you have any problems while taking Fasigyn, even if you do not think the problems are connected with the medicine or are not listed in this leaflet. Like other medicines, Fasigyn can cause some side effects. If they occur, most are likely to be minor and temporary. However, some may be serious and need medical attention.

Ask your doctor or pharmacist to answer any questions you may have.

Tell your doctor if you notice any of the following and they worry you:

  • generally feeling unwell
  • a metallic taste in the mouth
  • loss of appetite, feeling sick, stomach pain, diarrhoea or constipation
  • dark coloured urine
  • oral thrush - white, furry, sore tongue and mouth
  • vaginal thrush - sore and itchy vagina and/or discharge

These side effects are usually mild.

See your doctor immediately and before you take your next dose of Fasigyn if you notice any of the following:

  • asthma, wheezing or shortness of breath
  • hives, itching or skin rash
  • swelling of the face, lips or tongue which may lead to difficulty swallowing or breathing
  • fainting
  • tingling or numbness of the hands or feet, or muscle weakness

Tell your doctor immediately or go to Accident and Emergency (Casualty) at your nearest hospital if you notice any of the following:

  • headache, dizziness, a spinning sensation, shaky or unsteady movements
  • unusual tiredness or flu-like illness

These side effects are rare but may be serious and need urgent medical attention.

Other side effects not listed above may also occur in some patients.

Tell your doctor if you notice any other effects.

After using Fasigyn


Keep Fasigyn in its original packaging until it is time to use it. If you take Fasigyn out of its packaging, it may not keep as well.

Keep your Fasigyn in a cool, dry place where it stays below 25 degrees Celsius.

Do not store Fasigyn or any other medicine in the bathroom or near a sink. Do not leave it in the car or on a window sill. Heat and dampness can destroy some medicines.

Keep your Fasigyn where young children cannot reach it. A locked cupboard at least one and a half metres above the ground is a good place to store medicines.


If your doctor tells you to stop taking Fasigyn, or the tablets have passed their expiry date, ask your pharmacist what to do with any left over.

Product description

What it looks like

White, round tablets marked FAS 500 on one side and plain on the other, in packs of four.


Fasigyn contains 500 mg of tinidazole per tablet as the active ingredient. It also contains:

  • microcrystalline cellulose
  • alginic acid (400)
  • maize starch
  • magnesium stearate (470)
  • sodium lauryl sulfate
  • hypromellose
  • propylene glycol (1520)
  • titanium dioxide


Fasigyn is supplied in Australia by:

Pfizer Australia Pty Ltd
Sydney NSW 2000

Toll free number: 1800 675 229

Australian Registration Number:

AUST R 48414

This leaflet was revised on November 2019

Published by MIMS February 2020


Brand name


Active ingredient





1 Name of Medicine


6.7 Physicochemical Properties

Fasigyn contains the active ingredient tinidazole. Fasigyn (tinidazole) is a derivative of the substituted imidazole group of compounds. It is a pale yellow crystalline solid that is insoluble in water, but soluble in methanol and chloroform.
Chemical name: 1-(2-ethylsulfonylethyl)-2-methyl-5-nitro-imidazole.
Molecular formula: C8H13N3O4S.
Molecular weight: 247.3.

Chemical structure.

The structural formula of tinidazole is:

CAS number.


2 Qualitative and Quantitative Composition

Fasigyn tablets contain 500 mg of tinidazole.

3 Pharmaceutical Form

White, round, biconvex, film coated oral tablets engraved with "FAS 500" on one side and plain on the other.

5 Pharmacological Properties

5.1 Pharmacodynamic Properties

Mechanism of action.


Fasigyn (tinidazole) has been shown to be effective against Trichomonas vaginalis, Entamoeba histolytica and Giardia lamblia. Minimum inhibitory concentration (MIC) values for Trichomonas vaginalis ranged from 1.25 to 10 microgram/mL when the organism was incubated with tinidazole for six hours and 0.12-1.25 microgram/mL when the incubation period was 3 days. Minimum cidal concentration (MCC) for the same organism ranged from 1.25 to 40 microgram/mL and 1.25-2.5 microgram/mL in the two studies respectively.
The MIC for tinidazole against Entamoeba histolytica trophozoites after 48 hours incubation in Locke's medium was 40 microgram/mL. An MIC of 6.25 microgram/mL has been established for Entamoeba histolytica.
In the absence of suitable laboratory techniques the MIC/MCC for Giardia lamblia is not known.
Fasigyn (tinidazole) has also been shown to be effective against anaerobic bacteria including Bacteroides fragilis, other species of Bacteroides and Fusobacteria sp. Other organisms for which tinidazole is also bactericidal belong to species such as Peptococcus sp., Peptostreptococcus sp., Clostridium sp. (except C. difficile), and Eubacteria sp. Aerobic and facultative aerobic bacteria Arachnia, Propionibacteria and Actinomycetes are resistant to tinidazole.

Clinical trials.

No data available.

5.2 Pharmacokinetic Properties


Following oral administration the drug is rapidly absorbed. In healthy female volunteers given a single oral 2 g dose of tinidazole, peak serum levels of 51 microgram/mL were obtained 2 hours postadministration. At 24 hours mean serum concentration of tinidazole was 19 microgram/mL; at 48 hours, 4 microgram/mL and at 72 hours, 1.3 microgram/mL. The serum half-life of tinidazole is approximately 12.7 hours.


There is suggestive evidence that peak serum levels may be lower and serum half-life shorter in males than in females. The concentrations of tinidazole in various tissues and fluids of the female genital tract of gynaecological patients after a single 2 g oral dose have been reported. The concentrations in peritoneal fluid obtained at operation 8.5-15 hours after drug intake ranged between 16-40 microgram/mL. Fallopian tube specimens yielded 15-26 microgram/g tissue. Similar levels were obtained in specimens from myometrium, endometrium, vaginal secretions, cervix and omental fat. Cerebrospinal fluid (CSF) concentrations in subjects without meningitis were approximately 88% of the simultaneous serum concentrations.
Tinidazole is bound to plasma proteins to the extent of approximately 12%.

Metabolism and excretion.

It is excreted in the urine primarily as unchanged drug. Approximately 20% of the unchanged drug appears in the urine in 24 hours.

5.3 Preclinical Safety Data


In vitro mutagenicity results with tinidazole were mixed (positive and negative). Tinidazole is mutagenic in the Ames test and was positive for in vivo genotoxicity in the mouse micronucleus assay.


Animal carcinogenic studies are inadequate to exclude tumorigenic potential. However, as other drugs of this class have been shown to be tumorigenic in animals, the benefits and risks from the use of tinidazole should be carefully assessed in each case, particularly in relation to the severity of the disease, the age of the patient or if a longer than usual treatment period is required.

4 Clinical Particulars

4.1 Therapeutic Indications

Fasigyn is indicated for the oral treatment of:
Trichomonas vaginalis infections of the genitourinary tract in both female and male patients. When infection with Trichomonas vaginalis has been confirmed or is suspected, simultaneous treatment of the consort is recommended.
Amoebic dysentery and amoebic liver abscess.
Acute giardiasis and acute amoebic dysentery and amoebic liver disease in children.
The prevention of infection of the surgical site which may be contaminated or potentially contaminated with anaerobic organisms, for example during colonic, gastrointestinal and gynaecological surgery.

4.3 Contraindications

Fasigyn is contraindicated in patients with the following conditions.
1. Hypersensitivity to tinidazole, other 5-nitroimidazole derivatives, or any component of the tablet.
2. Blood dyscrasias or with a history of blood dyscrasias.
3. Active organic diseases of the central nervous system.
4. First trimester of pregnancy (see Section 4.6 Fertility, Pregnancy and Lactation, Use in pregnancy).
5. Nursing mothers, as Fasigyn (tinidazole) is present in breast milk (see Section 4.6 Fertility, Pregnancy and Lactation, Use in lactation).

4.4 Special Warnings and Precautions for Use

Haematological effects.

Fasigyn may produce mild transient leukopenia and neutropenia. It is, therefore, recommended that total and differential leukocyte counts be done before and after treatment with the drug if a second course of therapy is necessary.

Disulfiram-like reaction.

Alcoholic beverages should be avoided during therapy with Fasigyn and for at least 72 hours after discontinuing Fasigyn because of the possibility of a disulfiram-like reaction (abdominal cramps, vomiting, tachycardia and flushing).

Neurological effects.

If, during therapy with Fasigyn, abnormal neurological signs develop, therapy should be promptly discontinued (see Section 4.8 Adverse Effects (Undesirable Effects)).

Bacterial overgrowth.

During treatment with closely related chemical compounds, vaginal and intestinal monilial overgrowth has been reported and may necessitate treatment with nystatin.

Interactions with anticoagulants.

Closely related chemical compounds enhance the activity of warfarin and if Fasigyn is to be given to patients receiving this or other anticoagulants, the dosage of the latter should be recalibrated (see Section 4.5 Interactions with Other Medicines and Other Forms of Interactions).

Administration with food.

It is recommended that tablets be taken during or after a meal.

Use in renal impairment.

Because the drug is excreted in the urine caution should be exercised in patients with impaired renal function if administering a second or additional doses.

Use in the elderly.

No data available.

Paediatric use.

Experience in treating paediatric patients with this drug is relatively limited and information on safety is still incomplete.

Effects on laboratory tests.

No data available.

4.5 Interactions with Other Medicines and Other Forms of Interactions


Concurrent use of tinidazole and alcohol may produce a disulfiram-like reaction and should be avoided (see Section 4.4 Special Warnings and Precautions for Use, Disulfiram-like reaction).


Drugs of similar chemical structure have been shown to potentiate the effects of oral anticoagulants. Prothrombin times should be closely monitored and adjustments to the dose of the anticoagulant should be made as necessary (see Section 4.4 Special Warnings and Precautions for Use, Interactions with anticoagulants).

4.6 Fertility, Pregnancy and Lactation

Effects on fertility.

As with other agents in the 5-nitroimidazole class, tinidazole has been reported to produce testicular and spermatogenic adverse effects in male rats.
(Category B3)
Tinidazole crosses the placental barrier and enters the foetal circulation. Fasigyn is contraindicated during the first trimester of pregnancy. Animal studies suggest that tinidazole may have teratogenic potential. Benefit and risk from its use should, therefore, be carefully assessed and the drug may be used during the second and third trimester with caution and discretion and only if in the judgment of the attending physician the expected benefits outweigh the potential risk.
Tinidazole is secreted in breast milk. In view of its mutagenic potential, breastfeeding is not recommended. Tinidazole may continue to appear in breast milk for more than 72 hours after administration. Women should not breastfeed until at least three days after having discontinued Fasigyn.

4.8 Adverse Effects (Undesirable Effects)

Mild adverse reactions have been reported in about 15% of patients of which the most common were gastrointestinal. Reported mild side effects have generally been infrequent and self limiting.
All adverse reactions are presented in Table 1 by system organ class and frequency.

Reporting suspected adverse effects.

Reporting suspected adverse reactions after registration of the medicinal product is important. It allows continued monitoring of the benefit-risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions at

4.2 Dose and Method of Administration




2 g (4 x 500 mg tablets) orally as a single stat dose.



2 g orally as a single stat dose.


50 mg/kg bodyweight given as a single dose, up to a maximum of 2 g. It may be necessary to repeat this dose once in some cases.

Acute amoebic dysentery.


2 g orally as a single dose for 2 to 3 days. (In the occasional instance when a three day course is ineffective, treatment may be continued for ten days.)


50 mg/kg bodyweight up to a maximum of 2 g, given as a single daily dose on each of three successive days.

Amoebic liver abscess.


2 g orally as a single daily dose for 3 days. (In the occasional instance when a three day course is ineffective, treatment may be continued for five days.)
Total dosage varies, according to the virulence of the Entamoeba histolytica, between 4.5 to 10 g.


50 mg/kg bodyweight, up to a maximum of 2 g, given as a single daily dose on each of five successive days.
In amoebic involvement of the liver the aspiration of pus may be required in addition to therapy with Fasigyn.

Prevention of postoperative infection.


A single oral dose of 2 g approximately 12 hours before surgery.


There is no data available to allow dosage recommendations for children below the age of 12 in the prophylaxis of anaerobic infections.

Dosage adjustment.

Use in renal impairment.

Dosage adjustments in patients with impaired renal function are generally not necessary. However, because tinidazole is easily removed by haemodialysis, patients may require additional doses of tinidazole to compensate.

Method of administration.

Administration with food.

It is recommended that tablets be taken during or after a meal.

4.7 Effects on Ability to Drive and Use Machines

The effect of tinidazole on the ability to drive or operate heavy machinery has not been studied.

4.9 Overdose

Signs and symptoms.

Reports of overdoses in humans with tinidazole are anecdotal and do not provide consistent data regarding the signs and symptoms of overdose.

Treatment of overdosage.

There is no specific antidote for the treatment of overdosage with tinidazole. Treatment is symptomatic and supportive. Tinidazole is easily dialysable.
For information on the management of overdose, contact the Poison Information Centre on 13 11 26 (Australia).

7 Medicine Schedule (Poisons Standard)


6 Pharmaceutical Particulars

6.1 List of Excipients

Microcrystalline cellulose, alginic acid, maize starch, magnesium stearate, sodium lauryl sulfate, hypromellose, propylene glycol, titanium dioxide.

6.2 Incompatibilities

Incompatibilities were either not assessed or not identified as part of the registration of this medicine.

6.3 Shelf Life

In Australia, information on the shelf life can be found on the public summary of the Australian Register of Therapeutic Goods (ARTG). The expiry date can be found on the packaging.

6.4 Special Precautions for Storage

Store below 25°C.

6.5 Nature and Contents of Container

Blister packs of 4.

6.6 Special Precautions for Disposal

In Australia, any unused medicine or waste material should be disposed of by taking to your local pharmacy.

Summary Table of Changes