Metronidazole: is it an antibiotic? See what it is for and how to use it

The body’s immune system has as its main role the protection against harmful agents to the organism.

However, in cases of infections caused by the attack of external agents, such as bacteria and protozoa, there is often a need to use medications to combat the problem.

Thus, among the therapeutic resources that can be used is Metronidazole, a drug used in the treatment of various infections caused by some bacteria and protozoa.


What is Metronidazole?

Metronidazole is an antibiotic, used as an active ingredient in medicines.

It is used to treat infections caused by some bacteria and protozoa,

como a Gardnerella vaginalis e Trichomonas vaginalis .

It is used in the treatment of gastrointestinal, vaginal infections and skin problems, providing antibacterial and antiprotozoal action.

Its administration can be oral, by means of tablets, or topical, with ointment or vaginal gel – each of which has different indications. In general, the active ingredient is indicated for people over 12 years old.

In addition, there is also the injectable version, applied intravenously, used only in a hospital environment.

The choice of form of use will vary according to the patient’s clinical condition, being possible the administration of a single dose (administered only once) or daily doses, for a few days.

Is it antibiotic?

-Yeah . Metronidazole is an antibiotic medication, with antiparasitic activity.

Drugs antibiotics are those with potential to destroy or inhibit the growth of bacteria harmful to health without damaging the human body.

They act only against bacteria, not being used to fight viruses or fungi.

In general, there are two types of antibiotics:

  • Bactericide: directly kills bacteria;
  • Bacteriostatic: prevents the proliferation of bacteria, so that the body’s own immune system can fight infection.

Metronidazole is a bactericidal antibiotic, that is, it directly destroys bacteria.

What is metronidazole indicated for?

Metronidazole is indicated for the treatment of some pathologies caused by different bacteria and fungi. It is used to fight infections of the digestive and genital system, such as Giardiasis , Amebiasis , Trichomoniasis and vaginitis. More specifically, medication is indicated for:

He was gardening

Giardiasis is an infection caused by the protozoan Giardia lamblia , which settles in the small intestine or biliary tract of the human body.

It is transmitted through contaminated food or water. It can also occur through direct contact with people, for example, by touching the contaminated hand.

In addition, it can be propagated through contaminated waste. It is generally more common in people who do not have good hygiene conditions or live in regions without sanitation.

In general, symptoms include:

  • Tiredness;
  • Weight loss;
  • Sickness;
  • Swelling;
  • Abdominal cramps;
  • Diarrhea;
  • Eructation with bad taste (belch).


Amoebiasis is an infection in the large intestine caused by the protozoan Entamoeba histolytica .

It is transmitted through contaminated water or food and also through direct contact with contaminated fecal material.

When they appear, the first symptoms are:

  • Diarrhea with colic;
  • Tiredness;
  • Abdominal discomfort;
  • Stools with blood or mucus;
  • Pain in the rectum during bowel movement;
  • Excessive gases;
  • Chills;
  • Slimming;
  • Colitis (inflammation of the colon).


Trichomoniasis is a disease caused by the protozoan Trichomonas vaginalis .

It is a sexually transmitted disease (STD), that is, it is transmitted through unprotected sexual intercourse with an infected person.

In rare cases, propagation can occur through contaminated objects and toilet seat.

In general, in women, the protozoan usually settles in the lower genital tract (vulva, vagina, cervix and urethra). In men, on the inside of the penis, the urethra.

Symptoms are usually:

In women:

  • Smelly discharge;
  • Genital redness;
  • Feeling of urinary urgency;
  • Bleeding and vaginal itching;
  • Inflammation of the vaginal area.

In men:

  • Discharge with unpleasant smell;
  • Itch;
  • Burning sensation when urinating or during ejaculation;
  • Urinary urgency.

Read more: What is the best ointment for smelly discharge?


Vaginitis is an inflammation of the vaginal mucosa and, in some cases, the vulva (outside of the genital region).

It is caused by the bacteria Gardnerella vaginalis , which is naturally part of the woman’s intimate region.

Despite being a microorganism naturally present in the genital region, when there is an imbalance of flora, there may be a predominance of this bacterium and the manifestation of vaginitis.

In general, the main symptoms of the pathology are:

  • Abnormal vaginal discharge;
  • Vaginal itching;
  • Burning sensation;
  • Bad smell in the intimate area.

Anaerobic bacteria infections

Anaerobic bacteria are those that grow in the presence of low concentrations or absence of oxygen.

Some of them can cause gastrointestinal or pelvic infections in women. Such cases can be treated with Metronidazole.

Some of the bacteria of this type that can cause pathologies are:

  • Bacteroides fragilis;
  • Fusobacterium sp;
  • Clostridium sp;
  • Eubacterium sp;
  • Anaerobic coconuts.

Presentation: What are the options for Metronidazole?

The medicine Metronidazole has different presentations, which can be used according to the patient’s clinical condition.

They are:


The tablet version is one of the most common of Metronidazole. It is usually sold in doses of 250mg and 400mg.

Metronidazole tablets combined with other medications are included in the protocol for the treatment of infections and parasites in the digestive system, pelvic inflammatory disease and urethritis ( inflammation of the urethra ) in men, although it is not the main indication of the package inserts.

It is indicated for adult and pediatric use over 12 years.

Ointment / cream

Metronidazole in the form of a cream or ointment (topical use) is generally indicated for skin-related infections, such as rosacea treatment – a condition that causes redness in the dermis. For gynacological infections, gynecological ointment is the only presentation indicated for treatment.

In general, it has concentrations of 100mg / g or 125mg / g.

The cream version is usually accompanied by another substance, Nystatin, which is an active ingredient with antifungal potential.

Together, these substances act to fight infections.

In ointment or cream form, in general, Metronidazole is indicated for adult use.


The Metronidazole gel presentation is, in general, indicated for the treatment of pathologies in the female intimate region, such as trichomoniasis.

It is usually available in concentrations of 100mg / g or 500mg / 5g.

This version is suitable for adult use.


Oral suspension is a type of presentation in which the package may contain the ready-made product straight from the laboratory or just a powdered bottle and instructions for preparation.

In general, this version is one that, when left to stand, leaves visible particles mixed in the liquid, or deposited at the bottom of the flask. Therefore, the liquid must be stirred well before being administered.

To be marketed as an oral suspension, the substance used as an active ingredient must be insoluble in water, which does not occur with Metronidazole.

Therefore, in this presentation, the substance Benzoilmetronidazole, a derivative of Metronidazole, is used.

It has the same effects.

In general, each mL contains 40mg of Benzoilmetronidazole, which corresponds to 25mg of Metronidazole.

It is generally indicated for pediatric use over 1 year, for the treatment of gastro-intestinal infections.

Injectable Solution

The version in solution for injection is indicated for cases in which there is no recommendation or the patient is unable to receive the medication orally.

It is used for the treatment of infections by anaerobic bacteria and for the prevention and treatment of post-surgical infections, both for adults and children.

The administration of this version is only done in a hospital environment, by qualified professionals.

How to take according to the package leaflet?

The way in which the medicine is used varies according to its presentation: tablet, cream, gel or oral suspension.

It is worth remembering that, despite the information described below, it is important to follow the medical guidance for use .

In addition, doses and treatment periods may vary according to the patient’s clinical condition.

In general, according to the package leaflet, the form of administration is:


In the tablet version, the package insert indicates to ingest the medicine together with water.

The dosage may vary according to the condition to be treated. She can be:


For the treatment of Trichomoniasis, the dosage recommended by the package insert is:

Amount (mg)FrequencyTime course
250mg2 times a dayfor 10 days
400mg2 times a dayfor 7 days

If administration is done in a single dose, the recommended is an intake of 2g.

Vaginitis and Urethritis

In the case of pathologies of the intimate region caused by the bacteria Gardnerella vaginalis , such as vaginitis and urethritis, the recommended dosage is:

  • Between 400mg to 500mg a day, 2 times a day, for a period of 7 days.

If the indication is a single dose, the administration of 2g is indicated on the first and third day of treatment.

He was gardening

To treat Giardiasis, it is recommended to administer:

  • 250mg of Metronidazole, 3 times a day, for 5 days.


In the case of Amebiasis, the use may vary according to the clinical picture:

  • Intestinal amebiasis: 500mg, 4 times a day, for 5 to 7 days;
  • Hepatic amebiasis: 500mg, 4 times a day, for 7 to 10 days.

Anaerobic bacteria infections

To treat infections by anaerobic bacteria, according to the package insert, the indicated is:

  • 1 400mg tablet, 3 times a day, for 7 days.

In this case, it is recommended to eat after meals.

Ointment / Cream

The administration in ointment or cream is, in general, done to treat gynecological infections. The packages are accompanied by applicators.

In general, it is recommended to use 1 full applicator, preferably at night, for a period of 10 to 20 days, depending on medical advice.

To apply the medication, the steps are:

  1. Remove the cap from the tube and completely screw the applicator to the tip of the tube;
  2.  With one hand, hold the tube and, with the other, pull the plunger of the applicator until the end;
  3. With the plunger pulled and in the horizontal position, tighten the tube so that the gel fills the applicator cannula;
  4. Remove the applicator from the tube and close it;
  5. Insert the applicator deep into the vaginal cavity and push the plunger until the applicator is completely empty.

Do not reuse applicators. For each administration, use a new applicator.


Metronidazole in gel form can be used to treat infections in the female intimate region (gynecological gel) or for skin conditions, such as rosacea (dermatological gel).

Therefore, there is the gynecological and dermatological gel, being different products, however, both with Metronidazole as an active ingredient.

In general, the dosage varies depending on the treatment:

Vaginal infections

In the case of vaginal infections, the administration of the gel version is similar to that of the cream.

It is recommended to use 1 applicator per day, preferably at night, for 10 to 20 days.

The application steps are:

  1. Remove the cap from the tube and completely screw the applicator to the tip of the tube;
  2. With one hand, hold the tube and, with the other, pull the plunger of the applicator until the end;
  3. With the plunger pulled and in the horizontal position, tighten the tube so that the gel fills the applicator cannula;
  4. Remove the applicator from the tube and close it;
  5. Insert the applicator deep into the vaginal cavity and push the plunger until the applicator is completely empty.

Do not reuse applicators. For each administration, use a new applicator.


For topical treatment of rosacea, it is indicated that, with the skin properly cleaned and dry, it is administered:

  •  A thin layer of the gel in the affected region, 2 times a day (morning and night), for a period of 3 to 4 months.

Treatment time may vary according to the patient’s clinical condition and medical indication.


The oral suspension version is generally used for pediatric treatments, in the case of gastro-intestinal infections.

According to the package insert, it is recommended to administer orally, using the doser that comes with the package.

The dosage may vary according to the problem treated:

He was gardening

In the case of Giardiasis, the package insert indicates that the dose is:

  • For children aged 1 to 5 years: 5mL, twice a day, for 5 days;
  • For children from 5 to 10 years: 5mL, 3 times a day, for 5 days.


For the treatment of Amebiasis, the use may vary according to the clinical picture:

  • Intestinal amebiasis : 0.5mL / kg, 4 times a day, for 5 to 7 days;
  • Hepatic amebiasis : 0.5mL / kg, 4 times a day, for 7 to 10 days.

When does Metronidazole start taking effect?

The time to onset of the effects of Metronidazole may vary depending on the form of administration chosen. In general, the tablet and oral suspension versions have effects more quickly.

The maximum absorption time of Metronidazole, that is, the time it takes the drug to be fully absorbed by the body, for each presentation is:

  • Tablet: 1 to 2 hours;
  • Ointment / cream: 8 to 12 hours;
  • Gel: 8 to 12 hours;
  • Oral suspension: approximately 1 hour.

Despite this, it is worth mentioning that the symptoms will not necessarily disappear soon after the onset of the action.

The time for the complete elimination of the pathology can vary according to the clinical picture and response of the organism.

Who is using Metronidazole tablet may have a relationship?

It depends . In the package insert there is no contraindication for sexual intercourse during oral use. However, in some cases, it may be recommended to avoid the act.

If the patient is undergoing gastrointestinal treatments, for example, having sex while using the pill, in general, will not interfere with the effectiveness of the medication.

However, if the pathology is related to infections in the genital area, it is recommended to avoid sexual intercourse, as this can stimulate the worsening of the infectious condition.

In addition, sex during an intimate infection can facilitate the spread of other sexually transmitted diseases.

Thus, although the sexual act does not necessarily interfere with the effectiveness of Metronidazole tablet, it is worth waiting for the pathology to be completely treated in order to have the relationship.

Does it have side effects?

Like other medicines, Metronidazole can cause side effects in some people.

However, it is worth remembering that each organism reacts differently to medication. That way, not all people will necessarily suffer from the adverse symptoms.

In addition to fever , a general reaction of the body, the specific side effects are:

Gastrointestinal disorders

Among the gastrointestinal changes are:

  • Epigastric pain (stomach pain);
  • Oral mucositis (inflammation of the soft tissues of the mouth);
  • Pancreatitis (inflammation of the pancreas);
  • Anorexia;
  • Nausea;
  • Threw up;
  • Diarrhea;
  • Changes in taste;
  • Discoloration of the tongue;
  • Feeling of rough tongue.

Read more: Anorexia: what it is, symptoms and treatment

Disorders of the immune system

The immune system can be affected by side effects. The main reactions are:

  • Angioedema (presence of skin edema);
  • Anaphylactic shock (severe allergic reaction).

Disorders of the nervous system

Among the side effects that can affect the nervous system are:

  • Neuropathy (disease that affects the nerves);
  • Headaches;
  • Convulsions;
  • Dizziness;
  • Symptoms of encephalopathy (change in the functioning of the brain);
  • Change in gait (difficulty walking);
  • Nystagmus (involuntary and repetitive movement of the eyeball);
  • Dysarthria (difficulty in articulating words);
  • Ataxia (impaired motor coordination);
  • Aseptic meningitis (inflammation of the membranes and tissues that surround the brain).

Psychiatric disorders

Psychiatric disorders that can be caused by the use of Metronidazole are:

  • Depressive mood;
  • Psychotic changes (confusion and hallucinations).

Visual Disorders

Among the side effects that cause changes in vision are:

  • Diplopia (double vision);
  • Myopia (short-sightedness);
  • Decreased visual quality;
  • Change in the visualization of colors;
  • Optic neuropathy (disease that affects the optic nerves).

Ear Disorders

Reactions related to the ear are:

  • Hearing deficiency;
  • Hearing loss;
  • Ringing in the ear.

Disorders of the blood and lymphatic system

The side effects related to blood and lymph that may occur are:

  • Agranulocytosis (decrease in white blood cell count);
  • Neutropenia (decrease in the number of neutrophils – defense cells – in the blood);
  • Thrombocytopenia (decrease in the number of blood platelets).

Hepatobiliary disorders

The liver and bile ducts can also be affected by the use of the medication. The main adverse reactions are:

  • Cholestatic or mixed hepatitis (inflammation of the liver);
  • Injury to liver cells;
  • Jaundice (disease that causes yellowing of the skin and eyes);
  • Increased liver enzymes;
  • Failure of liver function.

Skin disorders

Side effects that can affect the skin and subcutaneous tissues are:

  • Rash (skin rashes);
  • Itching;
  • Blush;
  • Hives (rash);
  • Pustular eruptions (eruptions with pus on the skin);
  • Acute generalized exanthematic pustulosis (a rare disease that causes pustules to appear on the skin, accompanied by high fever and an increase in leukocytes – white blood cells – in the blood);
  • Stevens-Johnson syndrome (blistering of mucous membranes and large areas of the body);
  • Toxic epidermal necrolysis (generalized rash).

Price and where to buy?

The price of Metronidazole can vary according to the geographic region, establishment of purchase and brand indicated on the prescription.

There are different categories for classifying drugs, and the choice may interfere with the final value: reference, generic, similar or interchangeable similar.

To compare prices and make the purchase, it is possible to use the website of Consulta Remédios , which indicates the best prices in different pharmacies in each region.

The available options are:


Reference drugs are those that gave rise to the medication formula. Its effectiveness, safety and quality are scientifically proven and approved by Anvisa.

Metronidazole reference drugs and their prices * are as of:

  • Flagyl Compressed – R $ 16.61;
  • Flagyl Gel Vaginal — R$40,37;
  • Rozex – R $ 48.44.

* Prices consulted in May 2020. Prices may change.


Generic drugs are those that have the same active ingredient, dose, pharmaceutical form, indication and route of administration as the reference, but without the commercial nomenclature.

Thus, it is marketed by the name of the active ingredient.

Some generic options and * values ​​are from:

  • Metronidazole Neo Chemical Tablet – R $ 10.08;
  • Metronidazole Compressed Teuto – R $ 7.59;
  • Metronidazole Prati-Donaduzzi Tablet – R $ 9.48;
  • Metronidazol Gel Vaginal Teuto — R$15,66;
  • Metronidazole Neo Chemical Gel – R $ 20.59;
  • Metronidazol Gel Prati-Donaduzzi – R $ 17.37.

* Prices consulted in May 2020. Prices may change.


Similar are the drugs that have the same efficacy and effect as the reference, however, they may have, for example, different excipients, expiration date, labeling and product size.

Among Metronidazole’s similar options and their initial values ​​* are:

  • Neo Metrodazol — R$13,56;
  • Flagimax Gel — R$27,81.

* Prices consulted in May 2020. Prices may change.

Similar Interchangeable

Interchangeable similars are those that, as well as conventional similars, have proven efficacy and effect similar to the reference drug.

The difference is that these products can replace, at the time of purchase, the reference drugs, even if they have been prescribed in the medical prescription.

Among the options available for interchangeable similars and their prices *, are:

  • Canderm — R$17,82;
  • Helmizol Tablet – R $ 25.75;
  • Trinodazol — R$27,13.
  • Helmizol Gel Vaginal — R$15,10.

* Prices consulted in May 2020. Prices may change.

The use of medications such as Metronidazole is a recurring feature in the lives of some people.

Therefore, it is important that the patient understands the mechanisms and effects of each treatment, so that he / she is aware of the steps to combat a pathology.

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