How Long Ivermectin Stays in Your System

According to the prescribing information for the ivermectin tablet, the plasma half-life of ivermectin in people is about 18 hours after a dose by mouth, so the amount in the blood falls by about half roughly every 18 hours. The label also says the body clears ivermectin and its breakdown products almost entirely in the stool over an estimated 12 days, with less than 1% leaving in the urine.

This page explains what those numbers from the label mean, how the body handles ivermectin, and what to know about drug tests and blood work. It is general education, not medical advice, and it does not cover dosing.

What "half-life" means for ivermectin

A medicine's half-life describes how quickly its level in the blood goes down. For ivermectin, the prescribing information gives a plasma half-life of approximately 18 hours following oral administration. In plain terms, about 18 hours after the highest level is reached, roughly half as much is left in the blood, and the level keeps falling by about half over each further stretch of about 18 hours.

The label also reports that, in studies of healthy volunteers who had not eaten, ivermectin reached its highest level in the blood at about 4 hours after the dose. So the level rises over the first few hours and then gradually falls.

Half-life is about the amount in the blood. It is a different measure from how long it takes the body to clear the medicine and its breakdown products completely, which the label describes separately (see the next section).

How the body clears ivermectin

The prescribing information describes three steps:

• Absorbed from the gut. Ivermectin is taken by mouth as a tablet. The label notes that a high-fat meal increased the amount absorbed by about two and a half times compared with taking it on an empty stomach, which is why the label says the tablet should be taken on an empty stomach with water. Follow the directions on your own prescription label.
• Broken down in the liver. The label says ivermectin is metabolized in the liver. Laboratory studies found that it is broken down mainly by an enzyme called CYP3A4, with smaller roles for two other enzymes.
• Removed mostly in stool. Ivermectin and its breakdown products are excreted almost exclusively in the feces over an estimated 12 days. Less than 1% of the dose leaves in the urine.

That last point is why ivermectin is described as leaving the body mostly through the stool rather than the kidneys.

Why the timeline can differ from person to person

The figures on the label are averages from studies, and the label shows that levels varied widely between volunteers. Several things can affect how a medicine is handled in an individual:

• Food. As above, the label reports that a high-fat meal increased absorption.
• Liver function. Because the liver breaks ivermectin down, the label advises that treatment of older adults should be cautious, reflecting the greater frequency of decreased liver, kidney or heart function and of other medicines in that age group.
• Other medicines. Because CYP3A4 is involved, medicines that affect that enzyme may matter. Our page on drug interactions to know about covers what to tell your provider, and MedlinePlus advises telling your doctor and pharmacist about all prescription and nonprescription medicines, vitamins and supplements you take.

Your prescribing provider looks at these factors for you. Don't change how you take the medicine because of a half-life figure.

Pregnancy and breastfeeding

The prescribing information says ivermectin passes into human milk in low concentrations and that it should not be used during pregnancy because safety in pregnancy has not been established. If you are pregnant, could become pregnant or are breastfeeding, tell your provider before treatment. See who should not take these medications for more.

Does ivermectin show up on a drug test?

MedlinePlus explains that drug tests look for illegal drugs and for misuse of certain prescription medicines, such as opioids, barbiturates and benzodiazepines. Ivermectin is an antiparasitic medicine and is not one of the drug types MedlinePlus lists.

MedlinePlus also notes that the type of urine screen often done first can give false positive results, and that a false positive can happen when the test reacts with other chemicals from prescription or over-the-counter medicines. Before any drug test, MedlinePlus advises telling the testing professional about every prescription drug, over-the-counter medicine and supplement you take. MedlinePlus says a positive result is usually followed by a second test to make sure the first one was correct.

Does ivermectin show up in routine blood work?

Routine blood tests measure specific things, not every medicine in your body. According to MedlinePlus:

• A complete blood count (CBC) measures the number and size of your red blood cells, white blood cells and platelets, plus hemoglobin and hematocrit.
• A comprehensive metabolic panel (CMP) measures 14 substances, such as glucose, calcium, electrolytes, proteins and markers of kidney and liver function.

Neither panel measures ivermectin itself. Still, tell the clinician ordering your blood work about any medicine you have taken recently, so they can read the results with the full picture. If you are curious about how blood tests are used to look for parasites, see can a blood test detect parasites?

Getting a prescription through Get It Prescribed

Get It Prescribed is a telehealth service for adults. A licensed provider reviews a written health assessment, including your current medicines, and decides whether ivermectin is appropriate for one of its labeled uses: intestinal strongyloidiasis and onchocerciasis (river blindness). For an overview of the medicine, see what is ivermectin? No prescription is guaranteed, and the provider may recommend testing or an in-person visit instead. How it works shows each step.

The medicines dispensed through Get It Prescribed are compounded preparations made by a licensed compounding pharmacy. They are not FDA-approved, the FDA has not reviewed them for safety, effectiveness or quality, and they are not generics of, or substitutes for, the brand-name products. The figures on this page come from the prescribing information for the brand-name tablet.

The cost is a one-time $50 provider consultation fee, plus $3.00 per ivermectin tablet if a prescription is issued, with the quantity decided by the provider. The service is available in all 50 states and the District of Columbia; some states require a live phone or video visit.

This article is general education, not medical advice. It does not replace an evaluation by a licensed clinician who knows your history.

Related questions

What is the half-life of ivermectin in humans?

The prescribing information gives a plasma half-life of approximately 18 hours after a dose by mouth. That means the level in the blood falls by about half roughly every 18 hours.

How is ivermectin removed from the body?

The label says ivermectin is broken down in the liver and that it and its breakdown products are excreted almost entirely in the stool over an estimated 12 days. Less than 1% of the dose leaves in the urine.

Will ivermectin show up on a drug test?

Ivermectin is not one of the drug types MedlinePlus lists for drug tests, which look for illegal drugs and misuse of medicines such as opioids. Screening tests can give false positives, so tell the testing professional about every medicine you take.

Does food change how much ivermectin is absorbed?

Yes. The prescribing information reports that a high-fat meal increased absorption about two and a half times compared with an empty stomach, and it says the tablet should be taken on an empty stomach with water.

Does ivermectin pass into breast milk?

The prescribing information says it is excreted in human milk in low concentrations. Talk with your provider before treatment if you are breastfeeding.

Sources

• DailyMed: ivermectin tablet prescribing information — plasma half-life about 18 hours; peak level about 4 hours; metabolized in the liver mainly by CYP3A4; excreted almost exclusively in feces over about 12 days, under 1% in urine; high-fat meal raised absorption about 2.5 times; take on an empty stomach with water; excreted in human milk; not for use in pregnancy; caution in older adults.
• MedlinePlus: Ivermectin — how the tablet is taken; tell your doctor and pharmacist about all medicines and supplements.
• MedlinePlus: Drug Testing — what drug tests look for; false positives from other medicines; tell the tester about all medicines.
• MedlinePlus: Complete Blood Count (CBC) — what a CBC measures.
• MedlinePlus: Comprehensive Metabolic Panel (CMP) — the 14 substances a CMP measures.
• FDA: Compounding and the FDA — Questions and Answers — what compounded preparations are and how they are regulated.