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Generic Name: ivermectin
Brand Name: Stromectol
Drug Class: Anthelmintics
What is ivermectin, and what is it used for?
Ivermectin is an antiworm (anthelmintic) medication used to treat intestinal strongyloidiasis and river blindness (onchocerciasis), types of diseases caused by parasitic roundworm (nematode) infestations. Ivermectin belongs to the drug class avermectins, a group of broad-spectrum antiparasitic agents, and is used off-label in the treatment of many types of worm and mite infections.
Intestinal strongyloidiasis is caused by the larvae of Strongyloides stercoralis, which are present in the soil in free form, and penetrate the skin when people come into contact with them. The larvae migrate through the bloodstream into the lungs from where they get coughed up and swallowed, and reach the intestines, to grow into adult worms and lay eggs. The eggs hatch and the newly hatched larvae are shed in the stools, but some of the larvae reenter the colon and cause auto reinfection. Strongyloidiasis is prevalent in tropical and subtropical regions of the world and is also reported during the summer months in temperate regions.
River blindness is caused by Onchocerca volvulus species of nematodes, and is transmitted by the bite of infected blackflies, a type of biting insect found near fast-flowing streams in tropical regions in Africa, a few countries in South America, and Yemen. When a blackfly bites an infected human, the larvae get into the fly, develop inside, migrate to its proboscis, and get into the next human the infected blackfly bites. The larvae mature into adults, live in fibrous nodules under the skin, mate and reproduce, and can cause blindness if they get into the eyes.
Ivermectin binds to the parasite’s nerve and muscle cell membranes and increases their permeability to chloride ions, leading to paralysis and death of the parasites. Ivermectin can kill only the intestinal stages of the Strongyloides stercoralis worms, and the larvae stage of Onchocerca volvulus, but not the adult Onchocerca worms, which have to be surgically removed from the subcutaneous tissue.
Ivermectin was developed as a veterinary anthelmintic, but is also used to treat humans as well. The two formulations are different and humans should not use the veterinary formulation, the dosage can be highly toxic to humans. The FDA has not authorized or approved ivermectin for the treatment or prevention of COVID-19 in people or animals. Current data do not show evidence of safety and efficacy of ivermectin for these indications.
Uses of ivermectin include:
FDA-approved:
- Intestinal strongyloidiasis caused by Strongyloides stercoralis
- Onchocerciasis/river blindness caused by Onchocerca volvulus
Off-label uses include:
- Head lice infestation (pediculosis capitis)
- Eye-lid inflammation (blepharitis) caused by Demodex folliculorum mites
- Ascariasis cause by intestinal roundworm Ascaris lumbricoides
- Filariasis caused by Mansonella ozzardi or Mansonella streptocerca
- Scabies caused by Sarcoptes scabiei
- Gnathostomiasis caused by Gnathostoma spinigerum
- Cutaneous larva migrans caused by hookworms
- Trichuriasis caused by whipworms, Trichuris trichiura
- Filariasis caused by Wuchereria bancrofti
Warnings
- Do not use ivermectin in patients who are hypersensitive to any of its components
- Ivermectin used in the treatment of onchocerciasis may cause severe allergic response known as Mazzotti reaction with symptoms such as skin rash, hives, itching, fever, lymph node swelling, and inflammations in eye or joints; patient should be monitored for such reactions and treated with supportive care
- Neurotoxicity has been reported with the use of ivermectin treatment in onchocerciasis; if neurological symptoms develop, discontinue therapy and provide supportive care
- There are rare reports of patients with onchocerciasis who are also infected with eyeworm (Loa loa) developing brain disease (encephalopathy) spontaneously or with ivermectin treatment; use with caution in patients who have had exposure to Loa loa-endemic areas, after pretreatment assessment for loiasis, and monitor after therapy
- Repeated stool examination is necessary to establish clearance of infection in strongyloidiasis
- Ivermectin does not kill the adult Onchocerca volvulus worms; repeated follow-up and retreatment are required
- There have been rare reports of increased blood clotting time; avoid concurrent use with blood thinners such as warfarin
- Immunocompromised patients may require repeated treatment and suppressive therapy to control extraintestinal strongyloidiasis
QUESTION
Ringworm is caused by a fungus.
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What are the side effects of ivermectin?
Common side effects of ivermectin include:
- Mazzotti reaction in treatment of onchocerciasis including:
- Itching (pruritus)
- Rash with raised lesions (papular rash)
- Rash with pustules (pustular rash)
- Hives (urticaria)
- Skin (swelling) edema
- Fever
- Joint pain (arthralgia)
- Inflammation of the synovial membrane on joints (synovitis)
- Enlargement and tenderness of lymph nodes in:
- Armpits (axillary nodes)
- Neck (cervical nodes)
- Groin (inguinal nodes)
- Ophthalmic reactions including:
Less common side effects of ivermectin include:
- Abdominal pain
- Nausea
- Vomiting
- Diarrhea
- Constipation
- Loss of appetite (anorexia)
- Elevated levels of liver enzymes AST and ALT
- Decrease in white cell count
- Increase in hemoglobin
- Increase in eosinophil immune cell count (eosinophilia)
- Low red blood cell count (anemia)
- Low count of leukocyte immune cells (leukopenia)
- Weakness (asthenia)
- Fatigue
- Dizziness
- Drowsiness (somnolence)
- Tremor
- Vertigo
- Headache
- Muscle pain (myalgia)
- Peripheral edema
- Facial edema
- Drop in blood pressure when getting up after sitting or lying down (orthostatic hypotension)
- Rapid heart rate (tachycardia)
Rare side effects of ivermectin include:
- Abnormal sensation in the eyes
- Eyelid edema
- Inflammation of various tissues in the eyes including:
- Cornea (keratitis)
- Conjunctiva (conjunctivitis)
- Anterior uvea (uveitis)
- Choroid (choroiditis)
- Choroid and retina (chorioretinitis)
- Conjunctival hemorrhage (with onchocerciasis)
- Loss of vision
- Low blood pressure (hypotension)
- Worsening of bronchial asthma
- Severe skin reactions such as:
- Toxic epidermal necrolysis
- Stevens-Johnson syndrome
- Seizures
- Depression of central nervous system
- Impaired coordination, balance, and speech (ataxia)
- Disorientation
- Confusion
- Stupor
- Coma
- Brain damage (encephalopathy)
- Liver inflammation (hepatitis)
- Elevation of bilirubin
This is not a complete list of all side effects or adverse reactions that may occur from the use of this drug.
Call your doctor for medical advice about serious side effects or adverse reactions. You may also report side effects or health problems to the FDA at 1-800-FDA-1088.
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What are the dosages of ivermectin?
Tablet
- 3 g
Adult and pediatric:
Strongyloidiasis of the Intestinal Tract
- Under 15 kg: Safety and efficacy not established
- 15-24 kg: 3 mg orally once
- 25-35 kg: 6 mg orally once
- 36-50 kg: 9 mg orally once
- 51-65 kg: 12 mg orally once
- 66-79 kg: 15 mg orally once
- Over 80 kg: 200 mcg/kg orally once
Dosing considerations
- In general repeat doses are not necessary. Perform stool examinations to verify eradication of infection.
River Blindness (Onchocerciasis)
- Under 15 kg: Safety and efficacy not established
- 15-25 kg: 3 mg orally; may repeat in 3-12 months
- 26-44 kg: 6 mg orally; may repeat in 3-12 months
- 45-64 kg: 9 mg orally; may repeat in 3-12 months
- 65-84 kg: 12 mg orally; may repeat in 3-12 months
- 85 kg and greater: 150 mcg/kg orally; may repeat in 3-12 months
Dosing considerations
- Note: Does not treat adult worms (must be surgically excised)
Off-label uses
Adult:
Head Lice (Pediculosis capitis)
- 200 mcg/kg orally once; may require 1-2 additional doses repeated after 7 days
Blepharitis (Demodex folliculorum)
- 200 mcg/kg orally once as a single dose, THEN repeat dose once in 7 days
Filariasis Due to Mansonella ozzardi
- 6 mg orally as a single dose
Filariasis Due to Mansonella streptocera
- 150 mcg/kg as single dose
Scabies Due to Sarcoptes scabiel
- Immunocompromised patients: 200 mcg/kg as a single dose; may repeat in 14 days if necessary
Gnathostomiasis Due to Gnathostoma spinigerum
- 200 mcg/kg as a single dose
Administration
- Take on an empty stomach
- Monitor: Stool exams (strongyloidiasis)
Overdose
- Overdose of ivermectin can cause gastrointestinal symptoms including nausea, vomiting, diarrhea and abdominal pain, breathing difficulties, and neurological symptoms that can include seizure, dizziness, weakness, and blindness.
- Overdose is treated with symptomatic and supportive care that may include intravenous fluids, electrolytes, and respiratory support.
- Any undigested drug in the gastrointestinal tract may be eliminated with induced vomiting, gastric lavage, and purgatives.
What drugs interact with ivermectin?
Inform your doctor of all medications you are currently taking, who can advise you on any possible drug interactions. Never begin taking, suddenly discontinue, or change the dosage of any medication without your doctor’s recommendation.
- Ivermectin has no known severe interactions with other drugs.
- Serious Interactions of ivermectin include:
- erdafitinib
- lasmiditan
- quinidine
- sotorasib
- tepotinib
- Ivermectin has moderate interactions with at least 50 different drugs.
- Ivermectin has no known mild interactions with other drugs.
The drug interactions listed above are not all of the possible interactions or adverse effects. For more information on drug interactions, visit the RxList Drug Interaction Checker.
It is important to always tell your doctor, pharmacist, or health care provider of all prescription and over-the-counter medications you use, as well as the dosage for each, and keep a list of the information. Check with your doctor or health care provider if you have any questions about the medication.
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Pregnancy and breastfeeding
- There are no adequate and well-controlled studies on the safety of ivermectin use during pregnancy.
- Animal studies show fetal risk at doses that are toxic to the mother. Avoid use or use with caution if maternal benefits outweigh fetal risks.
- Ivermectin is present in breast milk in low concentrations. Use in nursing mothers only when the risk of delayed treatment outweighs the possible risk to the breastfed infant.
What else should I know about ivermectin?
- Take ivermectin exactly as prescribed, on an empty stomach
- Ivermectin does not kill the adult worms in onchocerciasis infection. Follow up with your healthcare provider until the infection is fully cleared.
- Ivermectin only kills the Strongyloides worms in the intestinal stage. Follow up for post-treatment stool examinations to make sure the infection is cleared.
- Never self-medicate with veterinary formulations of ivermectin either by ingestion, inhalation, injection, or exposure to body surfaces. Animal doses can be highly toxic to humans and can lead to life-threatening adverse effects.
- Do not self-medicate for prevention or treatment of COVID-19. Current data does not show evidence of the safety and efficacy of ivermectin for this viral infection.
- Store ivermectin safely out of reach of children
- In case of accidental overdose, immediately seek medical help or contact Poison Control
