Ornidazole

What Is Ornidazole?

Ornidazole is a prescription antimicrobial medicine. It belongs to a group called nitroimidazoles, which treat infections caused by certain parasites (protozoa) and certain bacteria that grow without oxygen (anaerobic bacteria). It is related to metronidazole and tinidazole. It is sold under various brand names and as generics in many countries in Europe, Asia, Africa, and Latin America. Ornidazole is not FDA-approved in the United States, so its approved uses and product labeling depend on the country where it is prescribed.

Approved Uses (Vary by Country)

Where it is licensed, ornidazole is commonly approved to treat:

• Amoebiasis, an intestinal infection with Entamoeba histolytica, including amoebic dysentery and amoebic liver abscess
• Giardiasis, an intestinal infection caused by Giardia
• Trichomoniasis, a sexually transmitted infection of the urogenital tract, in patients and their sexual partners
• Bacterial vaginosis
• Anaerobic bacterial infections, such as certain infections of the abdomen, pelvis, and gynecologic tract
• Prevention of anaerobic infection around some surgeries, especially abdominal and gynecologic procedures

Other Prescribed Uses

Some specialists prescribe ornidazole for other anaerobic or protozoal infections, including some dental infections, based on individual circumstances. These decisions belong to the treating specialist.

Available Forms and Strengths

• Tablets: commonly 250 mg, 500 mg, and 1,000 mg (strengths vary by country)
• Oral suspension or syrup: available in some countries
• Intravenous (IV) solution: commonly 500 mg per 100 mL, given in a hospital or clinic for more serious infections

In some countries, ornidazole is sold in fixed-dose combination products with other medicines (for example, certain antibiotics). This page describes ornidazole as a single ingredient. Combination products have their own labeling, and you should read it separately.

Available forms and strengths can vary by manufacturer and country.

What Is the Recommended Dosage of Ornidazole?

There is no single dose that fits everyone. The prescribed dose and length of treatment depend on several factors:

• The condition being treated. Some infections are treated with a single dose or a short course. Others need treatment for several days.
• Age. Children are usually dosed by body weight.
• Body weight.
• Liver function. People with severe liver disease may need a lower dose or less frequent dosing.
• Kidney function. Dose changes are usually not needed for reduced kidney function, but patients on dialysis may need dosing adjusted around their sessions.
• Sexual partners. For sexually transmitted infections such as trichomoniasis, partners are often treated at the same time.

Ornidazole comes as tablets, liquid (in some countries), and IV solution. Tablets are usually taken with or after food to reduce stomach upset.

Always take ornidazole exactly as your licensed medical specialist or pharmacist instructs. Do not change the dose, stop early, or extend treatment on your own, even if symptoms improve. Stopping too soon can allow the infection to return or make it harder to treat.

How Ornidazole Works

Ornidazole enters certain parasites and anaerobic bacteria. Inside these organisms, it is chemically changed into reactive forms that damage the organism’s genetic material (DNA). This stops the organism from surviving and multiplying. Human cells and organisms that use oxygen normally do not change ornidazole in the same way, which is why it targets these specific germs.

Ornidazole treats infections caused by susceptible organisms, and it helps the body clear the infection. How well it works depends on the type of organism, the location of the infection, and the person’s overall health. It does not work against viral infections, fungal infections, or bacteria that need oxygen to grow.

Is a Prescription Required to Buy Ornidazole Online?

In most countries where it is sold, ornidazole is a prescription-only medicine. In the United States, it is not an FDA-approved product, so it is generally not available through U.S. pharmacies. A licensed healthcare professional should evaluate you before it is prescribed.

Depending on the infection, the specialist may be:

• A primary care physician
• An infectious disease specialist
• A gastroenterologist (for intestinal infections)
• A gynecologist or urologist (for genital infections)
• A surgeon (when used around surgery)

Only buy ornidazole from a licensed pharmacy in your country that requires a valid prescription. Be careful with websites that sell it without one or that ship medicines from overseas without verification. Counterfeit, expired, or improperly stored products can be unsafe. Products labeled for animals are not approved for people and should never be used.

Side Effects of Ornidazole

Most people tolerate ornidazole well, but side effects can occur.

Common Side Effects

• Nausea or vomiting
• Metallic or unpleasant taste in the mouth
• Stomach pain or upset stomach
• Headache
• Dizziness or sleepiness
• Tiredness
• Dark or reddish-brown urine (usually harmless, caused by the medicine)
• Mild rash or itching

These are often mild. Talk to your pharmacist or doctor if they bother you or do not go away.

Serious Side Effects

Serious reactions are uncommon but possible. Get medical help right away if you notice:

• Numbness, tingling, burning, or weakness in the hands or feet (possible nerve problems)
• Seizures, confusion, severe dizziness, loss of balance, tremor, or trouble speaking
• Yellowing of the skin or eyes, dark urine with pale stools, or severe stomach pain (possible liver problems)
• Swelling of the face, lips, tongue, or throat, or trouble breathing (allergic reaction)
• Severe skin reactions, such as blistering, peeling, or sores in the mouth
• Fever, sore throat, or unusual bruising or bleeding (possible blood count changes)
• Severe mood changes or hallucinations

Call emergency services if you have trouble breathing or think you are having a life-threatening reaction.

Drug Interactions

Ornidazole can change how some other medicines work, and some medicines can change how the body handles ornidazole. Major categories include:

• Alcohol. Avoid alcohol during treatment and for at least 48 hours after the last dose, unless your specialist or the product label says otherwise. Other nitroimidazoles can cause flushing, nausea, vomiting, and rapid heartbeat when combined with alcohol.
• Blood thinners (such as warfarin and other coumarin-type medicines), which may increase bleeding risk. Blood tests are often used to adjust the dose.
• Muscle relaxants used in surgery (such as vecuronium), whose effects may be prolonged
• Seizure medicines (such as phenytoin and phenobarbital), which may change levels of ornidazole or the other medicine
• Disulfiram, used to treat alcohol dependence. Combining it with nitroimidazoles has been linked to confusion and psychosis.
• Lithium, since some nitroimidazoles can raise lithium levels
• Rifampin, an antibiotic that may lower levels of some nitroimidazoles
• Stomach acid medicines such as cimetidine, which may raise ornidazole levels
• Other medicines that can affect nerves or the liver, since side effects may add up

Tell your provider about all over-the-counter medicines, vitamins, supplements, and herbal products. Also mention any products that contain alcohol, such as some liquid cough and cold medicines.

Give your licensed medical specialist and pharmacist a complete, up-to-date list of everything you take. This list is not complete, so always check before starting or stopping any medicine.

Safety & Important Considerations

• Nervous system conditions: Ornidazole can affect the nervous system. It is used with caution, or avoided in some labeling, in people with epilepsy, multiple sclerosis, or other brain or nerve disorders. Report new numbness, tingling, balance problems, or seizures promptly.
• Liver disease: Ornidazole is processed mainly by the liver. People with liver disease may need a lower dose and closer monitoring.
• Kidney disease: Dose changes are usually not needed, but dialysis can remove the medicine from the blood, so timing of doses may matter.
• Blood disorders: Use caution in people with a history of blood disorders. Blood counts may be checked, especially with longer or repeated treatment.
• Long or repeated courses: Longer treatment raises the chance of nerve-related side effects. Your specialist may limit how long the medicine is used.
• Alcohol: Avoid alcohol during treatment and for at least 48 hours afterward.
• Pregnancy: Nitroimidazoles are generally avoided in the first trimester, and later use is decided by weighing benefits and risks. Tell your provider if you are pregnant, may become pregnant, or are trying to conceive.
• Breastfeeding: Ornidazole passes into breast milk. Your provider may advise pausing breastfeeding during treatment or choosing another medicine.
• Children: Ornidazole is used in children, with weight-based dosing determined by a specialist.
• Older adults: Older adults may be more sensitive to nervous system effects and often take multiple medicines, which raises the chance of interactions.
• Driving and machinery: Ornidazole can cause dizziness or sleepiness. Use caution until you know how it affects you.
• Sexual partners: For sexually transmitted infections, follow your specialist’s advice about treating partners and avoiding sexual contact until treatment is complete.

Who This Medication Is For

Ornidazole is prescribed for adults and children who have a confirmed or strongly suspected infection caused by a susceptible parasite or anaerobic bacterium, within its approved indications in their country. It may also be used to help prevent infection around certain surgeries. Whether it is appropriate depends on the type of infection, medical history, other medicines, and test results.

Who Should Not Take Ornidazole

Ornidazole is not suitable for everyone. Do not take it if:

• You have had an allergic reaction to ornidazole. Tell your provider if you have reacted to other nitroimidazoles such as metronidazole, tinidazole, or secnidazole, since cross-reactions can occur.
• You have been told by your specialist that you have a condition that makes it unsafe for you, such as certain brain or nerve disorders. Some product labels list epilepsy or multiple sclerosis as reasons to avoid it.

Use extra caution and discuss risks with your provider if you have:

• Liver disease
• Nerve or brain disorders, including a history of seizures
• A history of blood disorders
• Kidney disease requiring dialysis
• Pregnancy (especially the first trimester), plans for pregnancy, or breastfeeding
• Regular alcohol use

What to Do If You Miss a Dose

• Take the missed dose as soon as you remember.
• If it is almost time for your next dose, skip the missed one and go back to your regular schedule.
• Do not take two doses at once to make up for a missed dose.
• If you are unsure what to do, or you are taking a single-dose or short regimen, contact your licensed medical specialist or pharmacist. Missed doses can affect how well the infection is treated.

Related medications to Ornidazole

Other medicines exist for these infections, and the right one depends on the type and location of the infection. Only a licensed specialist can decide whether a different medicine is appropriate.

Other nitroimidazoles (same class):

• Metronidazole
• Tinidazole
• Secnidazole

Medicines from other classes, depending on the infection:

• Paromomycin, iodoquinol, and nitazoxanide, used for some intestinal parasite infections
• Clindamycin, used for some anaerobic infections and bacterial vaginosis
• Other antibiotics chosen by a specialist based on the bacteria involved

Do not switch or stop ornidazole without talking to your licensed medical specialist.

Storage Instructions

• Tablets: Store at room temperature, generally below 86°F (30°C), in the original container. Keep them dry and protected from moisture and light. Avoid storing them in a bathroom.
• Oral liquid (if prescribed): Keep tightly closed and follow the pharmacy label for storage and for how long to keep it. Shake well before each use if directed.
• IV solution: This is stored and handled by healthcare professionals. It should be protected from light and not frozen.
• Child safety: Keep all medicines out of reach and sight of children and pets, preferably in a locked or high cabinet.
• Do not use medicine past its expiration date. Ask your pharmacist about safe disposal of unused or expired medicine.

Disclaimer:

This page is for educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Patients must consult a licensed medical specialist, such as a primary care physician, infectious disease specialist, gastroenterologist, or gynecologist, depending on the type of infection, before starting, changing, or stopping treatment. Treatment decisions must be based on a full clinical evaluation by a qualified specialist. Information about dosing, strengths, and safety may change, so always follow the guidance of your prescriber and the current product labeling.