Tinidazole: What is it? How does it work? Side Effects, Action Mechanisms and Warnings

It is an antibiotic that fights bacteria in the body. It is used to treat certain infections such as bowel, vaginal or sexually transmitted infections.

How does it work?

Tinidazole is a synthetic Antiprotozoal agent. It shows activity both in vitro and in clinical infections against the following protozoa: Trichomonas Vaginalis, Giardia duodenalis (also called G. lamblia) and Entamoeba histolytica. It does not seem to have activity against most strains of vaginal lactobacilli.

Mechanism of action

Tinidazole is a prodrug and an antiprotozoal agent. The nitro group of Tinidazole is reduced in Trichomonas by a ferredoxin-mediated electron transport system.

It is believed that the free nitro radical generated as a result of this reduction is responsible for the antiprotozoal activity.

The mechanism by which tinidazole shows activity against the species of Giardia and Entamoeba is not known, although it is probably similar.


It is metabolized significantly in humans before excretion, in part by oxidation, hydroxylation and conjugation.

Tinidazole is the main constituent related to the drug in the plasma after human treatment, together with a small amount of the metabolite 2-hydroxymethyl.

Side effects

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue or throat.

Serious side effects, such as:

  • Fever.
  • Shaking chills.
  • Pains in the body
  • Symptoms of the flu.
  • Numbness.
  • Burning pain or tingling sensation
  • Convulsions

Less serious side effects may include:

  • Itching or vaginal discharge.
  • Nausea, vomiting, loss of appetite, indigestion.
  • Constipation, diarrhea, stomach cramps.
  • Feeling weak or tired
  • Headache, dizziness
  • Metallic or bitter taste in the mouth.

Interactions with other medications

Do not drink alcohol while taking Tinidazole, it can have unpleasant side effects, such as rapid heartbeat, severe nausea, vomiting, sweating and heat or tingling under the skin.

Check the label of the products and other medications you use, such as mouthwash or cough and cold medicines. The alcohol in these products can also cause a reaction if you use them while taking Tinidazole.

Tell your doctor about all other medications you use, especially:

  • Any other antibiotic
  • Anticoagulants such as Warfarin.
  • Cyclosporine.
  • Fluorouracilo.
  • Isoniazid (to treat tuberculosis).
  • Lithium.
  • Grass of San Juan.
  • Tacrolimus.
  • Antidepressants such as Nefazodone.
  • Antifungal medicines such as Clotrimazole, Itraconazole , Ketoconazole or Voriconazole.
  • Barbiturates such as phenobarbital.
  • Medications for the heart or blood pressure such as Diltiazem, Felodipine, Nifedipine, Verapamil and others.
  • HIV drugs such as Atazanavir, Delavirdine, Efavirenz, Etravirine, Fosamprenavir, Indinavir, Nelfinavir, Nevirapine or Ritonavir.
  • Medications for seizures, such as Carbamazepine , Felbamate, Oxcarbazepine, Phenobarbital, Phenytoin or Primidone.


  • Take exactly as prescribed by your doctor. Do not eat larger or smaller amounts or for longer than recommended. Follow the instructions on the medication label.
  • Take tinidazole with meals.
  • Some infections are treated with a single dose.
  • Do not share this medication with another person, even if you have the same symptoms as you.
  • If you are treating a sexually transmitted infection, make sure that your sexual partner seeks medical attention to be treated as well.
  • Take this medication for the full prescribed time. Your symptoms may improve before the infection has completely disappeared, but it is important that you complete your prescription.
  • Tinidazole will not treat a viral infection such as the common cold or the flu.


Keep at room temperature, away from moisture and heat.

Missed dose

Take the missed dose as soon as you remember it. Skip the missed dose if it is almost time for your next scheduled dose. Do not take additional medications to make up for the forgotten dose.

Elimination route

Tinidazole crosses the placental barrier and is secreted in breast milk. It is also excreted by the liver and kidneys, and by the urine mainly as unaltered drug (approximately 20-25% of the administered dose). About 12% of the drug is excreted in the stool.

Warnings and precautions

Seizures and peripheral neuropathy have been reported, the latter characterized mainly by numbness or paresthesia of an extremity in patients treated with Tinidazole.

The appearance of abnormal neurological signs requires the prompt suspension of treatment with Tinidazole.

Candidiasis vaginal

The use of this drug can cause vaginitis. In a clinical study of 235 women who received Tinidazole for bacterial vaginosis, a vaginal fungal infection developed in 11 (4.7%) of all study subjects.

Carcinogenesis, impairment of fertility

It has been reported that Metronidazole, a chemically related drug, is carcinogenic in mice and rats, but not in hamsters.

In several studies, Metronidazole showed evidence of pulmonary, hepatic and lymphatic tumors in mice and mammary and hepatic tumors in female rats.

Carcinogenicity studies with Tinidazole have not been reported in rats, mice or hamsters.

In a 60-day fertility study, Tinidazole reduced fertility and produced testicular histopathology in male rats at a dose level of 600 mg daily (approximately 3 times the highest human therapeutic dose based on conversions of body surface area) .

Spermatogenic effects resulted from dose levels of 300 and 600 mg daily. The level of adverse reaction not observed for testicular and spermatogenic effects was 100 mg daily (approximately 0.5 times the highest human therapeutic dose based on conversions of body surface area).

Use in specific populations

The pregnancy:

The use of tinidazole in pregnant patients has not been studied. Since Tinidazole crosses the placental barrier and enters the fetal circulation, it should not be administered to pregnant patients in the first trimester.

Toxicity studies of embryo-fetal development in pregnant mice indicated embryo-fetal toxicity or malformations at the highest dose level of 2,500 mg (approximately 6.3 times the highest human therapeutic dose based on conversions of body surface area).

In a study with pregnant rats, a slightly higher incidence of fetal mortality was observed at a maternal dose of 500 mg (2.5 times the highest human therapeutic dose based on conversions of body surface area).

No biologically relevant neonatal development effects were observed in rat neonates after maternal doses as high as 600 mg (the human therapeutic dose 3 times higher than the body surface area conversions).

Nursing mothers:

Tinidazole is excreted in breast milk in concentrations similar to those observed in serum. It can be detected in breast milk up to 72 hours after administration.

It is recommended to stop breastfeeding during treatment with Tinidazole and for 3 days after the last dose.

Pediatric use:

Apart from the use in the treatment of Giardiasis and Amebiasis in pediatric patients older than three years of age, the safety and effectiveness of Tinidazole in pediatric patients has not been established.

Geriatric use:

Clinical studies of Tinidazole did not include a sufficient number of subjects 65 years of age or older to determine whether they respond differently to younger subjects.

In general, the selection of doses for an elderly patient should be prudent, reflecting the greater frequency of decreased hepatic, renal or cardiac function, and concomitant disease or other pharmacological treatment.

Renal insufficiency:

Because the pharmacokinetics of Tinidazole in patients with severe renal impairment is not significantly different from that of healthy subjects, it is not necessary to adjust the dose in these patients.

Patients undergoing hemodialysis:

If Tinidazole is administered on the same day as before hemodialysis, it is recommended to administer an additional dose of the drug equivalent to half the recommended dose after the end of the hemodialysis .

Liver failure:

There are no data on the pharmacokinetics of Tinidazole in patients with hepatic impairment. A reduction in the elimination of Metronidazole (a chemically related drug) has been reported in this population. The usual recommended doses of Tinidazole should be administered with caution in patients with hepatic dysfunction.


You should not use this medication if you are allergic to Tinidazole or Metronidazole, or if you are in the first 3 months of pregnancy.

You should not breast-feed a baby while taking Tinidazole. However, you can start breastfeeding again 3 days after taking the last dose.

If you use a breast pump during your treatment, throw out the milk you collect while taking Tinidazole. Do not give it to your baby.

Before taking this drug, tell your doctor if you have kidney disease (or if you are on dialysis), epilepsy or other seizure disorder, a blood cell disorder such as anemia or low platelets, or a weak immune system.

Take this medication for the full prescribed time. Your symptoms may improve before the infection has completely disappeared. Tinidazole will not treat a viral infection such as the common cold or the flu.

Do not drink alcohol while using this medication, and at least wait 3 days after you finish your alcohol treatment.

A drug similar to Tinidazole has caused cancer in laboratory animals. It is not known if Tinidazole would have the same effect in animals or in humans. Talk to your doctor about your individual risk.

To make sure you can safely take Tinidazole, tell your doctor if you have any of these other conditions:

  • Kidney disease (or if you are on dialysis ).
  • Epilepsy or other seizure disorder.
  • Disorder of blood cells, such as anemia or low platelets.
  • Weak immune system