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Ivermectin - Uses, Dosage, Side Effects, Drug Warnings, and Precautions

Published on Sep 14, 2021   -  8 min read


Ivermectin is an anthelmintic drug that is highly effective against scabies, parasitic roundworm infections, onchocerciasis, strongyloidiasis, pediculosis, etc. Learn about its uses, dosage, drug warnings, side effects, precautions, drug interactions, and more.



Ivermectin is a prescription drug, and it is available as an oral tablet, topical cream, and lotion. This drug is absorbed from the gastrointestinal tract (oral) and is widely distributed in the body but does not enter the CNS (central nervous system). Instead, it enters the breast milk (less than 2%) and is excreted via feces and urine (less than 1%).

Ivermectin is an antiparasitic drug useful in treating round tapeworm infections, strongyloidiasis, and other parasitic infections. This drug has replaced Diethylcarbamazine for onchocerciasis. One dose of Ivermectin is given at 6 to 12 months intervals to produce a long-lasting reduction of Mycosis fungoides counts in the eye and skin without affecting the adult worm. Ivermectin is the only oral drug effective in scabies and pediculosis.


Ivermectin tablet contains,

  1. Active Ingredient: Ivermectin.

  2. Inactive Ingredients:

Ivermectin cream contains,

  1. Cetyl alcohol.

  2. Stearyl alcohol.

  3. Methyl parahydroxybenzoate.

  4. Propyl parahydroxybenzoate.

  5. Propylene glycol.

Drug Group:

Ivermectin belongs to the class of drugs called anthelmintics and is an extremely potent semisynthetic derivative of the anti-nematodal groups obtained from Streptomyces avermitilis. It is an antiparasitic medication that helps to treat infections of certain parasites in the body and is highly effective against scabies and pediculosis as well.

What Is Ivermectin Used For?

  1. It is the drug of choice for the single-dose treatment of onchocerciasis and strongyloidiasis.

  2. It is microfilaricidal (minute larvae of a filaria) but not macrofilaricidal and is highly useful in treating certain parasitic roundworm infections (Ascaris lumbricoides).

  3. Ivermectin is also highly effective in cutaneous larva migrans and ascariasis, while efficacy against Enterobius and Trichuris is moderate.

  4. It has been used as an add-on drug to Albendazole or Mebendazole in heavy trichuriasis.

  5. Certain types of insects, notably scabies and head lice, are killed by Ivermectin. A single dose of 0.2 mg/kg (12 mg in adults) has cured up to 91 to 100 % of patients with scabies.

  6. Also, AIDS patients with scabies have responded to the treatment.

  7. Nematodes start to develop tonic paralysis when exposed to Ivermectin, and so, this drug works by paralyzing and killing the parasites.

  8. Ivermectin is the only orally administered drug used for ectoparasitosis.

  9. Most cases of head or body lice have also been successfully treated.

  10. Only limited use of Ivermectin has been made in scabies and pediculosis because of the availability of efficacious topical agents.

How Does Ivermectin Work?

Ivermectin belongs to antiparasitic drugs, and these classes of drugs work similarly and are used to treat similar conditions. The oral tablet of Ivermectin works by binding to the parts of the parasite and starts to paralyze and kills the parasite. Also, this drug stops adult parasites from making larvae for a while and treats the infection.

It starts acting through a special type of glutamate-gated calcium channel, which is found only in invertebrates (nerve and muscle cells). This leads to an increase in the permeability of cell membranes to chloride ions with hyperpolarization of the nerve or muscle cell and, ultimately, leads to the death of the parasite. But these channels are not involved in the motor control of flukes and tapeworms.

Onset Of Action:

Ivermectin is well absorbed orally and reaches its peak plasma concentrations after 4 hours of taking the drug. It is sequestered in the liver and fat and has a half-life of 18 hours after oral administration. This drug has a high protein binding capacity of about 93 %, and the CYP3A4 isoenzyme metabolizes it, but no drug interactions related to this isoenzyme are known.

Expiry Date:

Avoid taking this medicine after it expires. You can verify the expiry date printed on the back of the pack before taking medicine.

What Is the Dosage and Administration of Ivermectin?

Dosage and administration of Ivermectin depends on the following,

Dosage of Ivermectin

Points to Remember:

How to Use Ivermectin?

  1. Before using the medicine, read the package label and follow all the instructions.

  2. Avoid taking this medicine in larger or smaller amounts or longer than the recommended period.

  3. The drug is taken orally, 1 hour before food or 2 hours after the food as directed by the doctor.

  4. This medication is taken on an empty stomach with a glass full of water (240 milliliters).

  5. Ivermectin is taken as a series of doses or a single dose or as directed by the doctor but is usually taken as a single dose.

  6. The dosage of the drug is based on the

  1. Weight of the patient.

  2. Medical condition.

  3. Response to treatment.

  1. It is better to inform your doctor if the condition persists or worsens.

  2. In order to effectively treat the infections, the patient needs to take Ivermectin again after several months to a year.

  3. When you have a weak immune response that is caused by a disease or by certain medications, more than one dose of Ivermectin needs to be taken.

  4. Normally, when a person has a weak immune system, then Ivermectin is taken on a regular basis by following the doctor's instructions.

  5. In order to know that this medicine is working, you may need to provide frequent stool samples.

  6. Always store this medicine at room temperature away from moisture and heat.

Missed Dose:

Ivermectin should be taken as instructed by the doctor, and in case you missed the dose, it can be taken as soon as you remember it. But if it is time for the next dose, you do not want to take the missed dose, and you can continue with your regular dosing schedule. Also, do not take a double dose in order to compensate for a missed one.

What Are the Drug Warnings and Precautions?

  1. Before using Ivermectin, inform your doctor or pharmacist if you have been allergic to this medicine or you have experienced any other allergies because this drug contains inactive ingredients, which may cause allergic reactions or any other problems. So, it is always better to speak to the doctor or pharmacist to know more information.

  2. Before using Ivermectin, you should tell your doctor or pharmacist about your medical history (present and previous), especially liver or kidney diseases.

  3. Ivermectin causes skin problems due to allergic and inflammatory reactions. These allergic reactions will start and look like parasitic infections, so consult your doctor when you experience severe itching, rash, or hives.

  4. If you have been to or lived in West or Central Africa, you may be infected with certain parasites such as Loa loa, African trypanosomiasis, etc., that could cause problems with Ivermectin treatment. These effects could rarely result in serious (possibly fatal) side effects on the brain (such as encephalopathy), so consult your doctor before usage and more information.

  5. This drug results in dizziness. Alcohol or marijuana (cannabis) makes you dizzy, so do not drive, do not use heavy machinery, or do not indulge in things that need alertness. Limit your alcoholic beverages and talk to your doctor if you are using marijuana (cannabis).

  6. Before undergoing any surgery, always inform your doctor or dentist about all the prescription, nonprescription and herbal products you use to avoid future complications.

  7. Ivermectin causes eye problems due to allergic and inflammatory reactions. These allergic reactions will start and look like parasitic infections, so consult your doctor when you experience redness, pain, swelling, and vision changes.

  8. In case of a weakened immune response (such as due to HIV infection), you may need repeat treatments with this medicine. Talk to your doctor for more details.

  9. The safety of Ivermectin in pregnant women and young children is not established.At the time of pregnancy, this medicine should be used when it is absolutely needed, and also discuss the risks and benefits of this medicine before usage with your doctor.

  10. It is said that this medication passes into breast milk and harms nursing infants, so consult with your doctor before breastfeeding.

What Are the Side Effects of Ivermectin?

Some common side effects caused by Ivermectin are,

The following are rare side effects, but stop the drug and seek the doctor’s help if you come across any of the following,

Allergic reactions due to Ivermectin are rare but stop the drug and get emergency medical help if you come across the following symptoms of a serious allergic reaction.

What Are the Drug Interactions of Ivermectin?

  1. The effectiveness of some drugs tends to change when they are taken with any other drugs or herbal products. Drug interactions increase the risk of serious side effects and cause the medicines to work improperly.

  2. Drug interactions do not occur often, and the doctor or pharmacist prevents these interactions by changing the usage of medications or by close monitoring. So, it is important to tell the doctor and pharmacist about the prescription, nonprescription, and herbal tablets you are taking.

  3. While taking medicine, do not suddenly start or stop or change the dosage of any other drugs you are currently taking without the doctor's approval.

  1. The list of drugs that may interact with Ivermectin include,

    1. Barbiturates:

      • Phenobarbital.

      • Butalbital.

    2. Benzodiazepines:

      • Clonazepam.

      • Lorazepam.

    3. Sodium oxybate (GHB).

    4. Valproic acid.

    5. Warfarin.

  1. Always keep a list of all the products you use and share the list with your doctor and pharmacist to avoid risk and serious complications.

What Are the Common Brand or Trade Names of Ivermectin?

The common brand names of Ivermectin are,


Last reviewed at:
14 Sep 2021  -  8 min read




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