Ivermectin Withdrawal Times: Meat, Milk and Egg Intervals From Every U

A withdrawal interval is the number of days that must pass between the last dose of a drug and the moment an animal is slaughtered or its milk or eggs enter the food supply. For ivermectin in the United States, that number is not a single figure: it is set product by product, species by species and route by route, and across FDA-approved ivermectin products it runs from 5 days for medicated swine feed under 21 CFR 558.300(e)(1) to 180 days for the sustained-release cattle bolus under 21 CFR 520.1197(d)(3). If you want to know which products those intervals attach to, start from the approved-product index and match the exact product in your hand, because a paste, an injection and a pour-on with the same active ingredient carry three different numbers.

Beef cattle in a corral chute at a working ranch, illustrating the pre-slaughter withdrawal period after ivermectin treatment

Two absences matter as much as the numbers. No FDA-approved ivermectin product in the US has an established milk withholding period — the labels and the regulations say a milk withdrawal time "has not been established" and then prohibit the use instead, for example at 21 CFR 522.1192(e)(2)(iii). And because ivermectin is not approved for any poultry species in the US, there is no egg or meat residue tolerance for poultry and no label anywhere that states an egg interval, as the authors of a 2025 Frontiers in Veterinary Science residue study state in their introduction. This page sets out what each US label and regulation actually says, dated, with the primary source for each figure.

Key takeaways

The ivermectin withdrawal time depends on the product, not the drug: cattle carry 35 days by injection (21 CFR 522.1192(e)(2)(iii)), 48 days by pour-on (21 CFR 524.1193(d)(3)), 24 days by the 0.153% oral paste (21 CFR 520.1192(e)(2)(iii)), 21 days for the ivermectin–clorsulon injection (21 CFR 522.1193(e)(3)) and 180 days for the sustained-release bolus (21 CFR 520.1197(d)(3)).
There is no ivermectin milk withdrawal on any approved US product. Dairy use is barred outright rather than timed.
Ivermectin withdrawal period sheep: 11 days before slaughter (21 CFR 520.1195(e)(2)(iii)). The sheep drench label carries no milk statement of any kind.
There is no ivermectin egg withdrawal because there is no poultry approval and no egg tolerance.
Any use outside the label — a different species, dose, route or frequency — is extralabel use under 21 CFR 530.3(a), the label interval no longer applies, and a veterinarian must establish a substantially extended withdrawal period under 21 CFR 530.20(a)(2)(ii).

What a withdrawal interval is and who sets it

A farm medicine cabinet holding plain unlabelled livestock drug bottles and dosing equipment of the kind that carry different ivermectin withdrawal intervals

FDA's Center for Veterinary Medicine sets withdrawal intervals as part of approving a new animal drug application, and for ivermectin most of them are then codified in Title 21 of the Code of Federal Regulations, so the number is regulatory text rather than a manufacturer's preference. The yardstick behind the number is a residue tolerance. Under 21 CFR 556.344(a), the acceptable daily intake for total residue of ivermectin is 5 µg/kg of body weight per day, and 21 CFR 556.344(b) sets tolerances for the marker residue 22,23-dihydroavermectin B_1a in five food-producing species: American bison liver 15 ppb, cattle liver 1.6 ppm and cattle muscle 650 ppb, reindeer liver 15 ppb, sheep liver 30 ppb, and swine liver and muscle 20 ppb each.

A withdrawal interval is therefore a residue-depletion period tied to a tolerance in a named target tissue. It is not a half-life, and the two are different magnitudes. The human label for STROMECTOL (ivermectin) tablets, in the DailyMed SPL version published 24 April 2025, gives a plasma half-life in man of approximately 18 hours; that figure has nothing to do with how long residues persist in a bullock's liver.

The master table: product, species, route, meat withdrawal, milk statement

Dairy cows being milked in a parlour, illustrating why ivermectin products carry no milk withholding period and are barred in dairy cattle

Every figure below is from the eCFR text or the DailyMed label cited in the last column. Intervals are pre-slaughter unless the wording is otherwise.

Product (application)	Species and route	Meat withdrawal	Milk statement	Primary source
IVOMEC Injection, 1% (NADA 128-409)	Cattle, subcutaneous, 200 mcg/kg (1 mL per 110 lb)	35 days	"Because a withdrawal time in milk has not been established, do not use in female dairy cattle of breeding age."	DailyMed SPL, label Rev. 08/2023, SPL effective 1 July 2026; 21 CFR 522.1192(e)(2)(iii)
IVOMEC Injection, 1% (NADA 128-409)	Swine, subcutaneous, 300 mcg/kg (1 mL per 75 lb)	18 days	None — the swine limitation is that one sentence	21 CFR 522.1192(e)(3)(iii)
IVOMEC Injection (Special Minor Use)	Reindeer and American bison, subcutaneous, 200 mcg/kg	56 days (label: "8 weeks (56 days)"); the regulation words the bison clause as 56 days of last treatment	None stated	21 CFR 522.1192(e)(4)(iii) and (e)(5)(iii)
IVOMEC Plus (ivermectin 1% + clorsulon 10%, NADA 140-833)	Cattle, subcutaneous, 1 mL per 110 lb	21 days	No milk withdrawal established; barred in female dairy cattle of breeding age	DailyMed SPL, label Rev. 06/2024; 21 CFR 522.1193(e)(3)
IVOMEC Pour-On, 5 mg/mL (NADA 140-841)	Cattle, topical, 1 mL per 22 lb (0.5 mg/kg)	48 days	Regulation: "Do not use on female dairy cattle of breeding age or on calves to be processed for veal."	DailyMed SPL, label Rev. 07/2024; 21 CFR 524.1193(d)(3)
IVOMEC Cattle Paste 0.153% (NADA 137-006)	Cattle, oral, 23 mg per 250 lb	24 days	No milk withdrawal established; barred in female dairy cattle of breeding age	21 CFR 520.1192(e)(2)(iii)
IVOMEC Sustained-Release Bolus, 1.72 g (NADA 140-988)	Ruminating calves over 12 weeks, 275–660 lb, oral bolus	180 days	No milk withdrawal time established	21 CFR 520.1197(d)(3)
IVOMEC Drench for Sheep, 0.08% (NADA 131-392)	Sheep, oral drench, 200 mcg/kg (3 mL per 26 lb)	11 days	No milk or dairy wording appears anywhere on the label or in 21 CFR 520.1195	DailyMed SPL, label Rev. 10/2024, SPL effective 31 October 2025; 21 CFR 520.1195(e)(2)(iii)
IVOMEC Premix for Swine, Type A article 2.72 g/lb (NADA 140-974)	Swine, medicated feed, 0.1 mg/kg body weight per day for 7 consecutive days	5 days	Not applicable	21 CFR 558.300(a) and (e)(1)
Equine paste 1.87% (e.g. ZIMECTERIN, NADA 134-314) and ivermectin meal 0.6%	Horses, oral, 91 mcg/lb (200 mcg/kg) paste; 136 mcg/lb (300 mcg/kg) meal	None — the food supply is closed instead: "Do not use in horses intended for human consumption."	Not applicable	21 CFR 520.1192(e)(1)(iii); 21 CFR 520.1194

Generics carry the same figures. On DailyMed, ivermectin injections under ANADA 200-429, ANADA 200-437 and ANADA 200-447 all state 35 days for cattle, 18 days for swine and 56 days for reindeer and bison; the ivermectin–clorsulon injection under ANADA 200-450 states 21 days; the sheep drench under ANADA 200-327 states 11 days; and the cattle pour-ons under ANADA 200-348 and ANADA 200-318 both state 48 days. One caution worth naming: the Privermectin Drench for Sheep SPL on DailyMed (SPL revised 9/2024) is a carton panel that carries no residue warning at all, even though it is approved under ANADA 200-327 — the absence of a printed interval on a package panel is not the absence of an interval.

The two screwworm emergency authorizations do not change the number

FDA issued an Emergency Use Authorization for IVOMEC injection against New World screwworm in cattle on 5 February 2026 (EUA 006689) and a second for generic Bimectin injection on 27 August 2026 (EUA 006729). Both fact sheets state that cattle must not be slaughtered for human consumption within 35 days of treatment, and FDA's FOI summary for EUA 006689 says plainly that the 35 days is the period "established under NADA 128-409." The EUAs are stricter than the approved label in one respect: they state that treated calves and calves born to treated cows must not be processed for veal. The 15 July 2026 EUA for Ivermectin Liquid for Horses sets no withdrawal period and instead bars use in horses intended for human consumption.

Products that must not be used in lactating dairy animals, and why

Backyard laying hens and a goat in a small farmyard, species for which no ivermectin egg or milk withdrawal interval exists in the United States

The reason there is no ivermectin milk withdrawal is stated on the labels themselves. Because a withdrawal time in milk was never established, the label cannot offer a discard period, so it removes the animal from dairy production instead. That prohibition appears on the IVOMEC injection, IVOMEC Plus and IVOMEC Pour-On labels on DailyMed and in the regulations for the 0.153% cattle paste (21 CFR 520.1192(e)(2)(iii)) and the sustained-release bolus (21 CFR 520.1197(d)(3)). Reading a milk restriction as "a few days off the tank" is the most consequential misreading available on these labels.

Three wording details are easy to miss. First, the pour-on regulation at 21 CFR 524.1193(d)(3) is blunter than its label, simply barring use on female dairy cattle of breeding age. Second, the approved labels restrict by breeding age, while the screwworm EUA fact sheets restrict by lactation status — "female dairy cattle producing milk for human consumption" — which is a narrower class. Third, sheep are not covered either way: the American Consortium for Small Ruminant Parasite Control notes in its sheep dewormer chart, last updated November 2024, that it provides no milk withholds because uniform milk withholds have not been established in sheep. Dairy goats are a separate problem again, covered in our note on dairy goats and the FARAD problem.

Species with no interval because there is no approval

A livestock producer writing treatment and withdrawal dates in a paper record book on a farm office desk

Goats. An Animal Drugs @ FDA advanced search for ivermectin with species "Goats" returned zero applications when retrieved on 28 September 2026. All ivermectin use in goats is extralabel. The ACSRPC goat dewormer chart (last updated November 2024) recommends, for the sheep drench used extra-label in goats at 0.4 mg/kg orally, a 20-day meat withdrawal and a 20-day milk withdrawal — and the same chart states those times are based on the most current information available from the Food Animal Residue Avoidance Databank and may change as new pharmacologic information is obtained. They are guideline recommendations derived from FARAD, not regulatory withdrawal periods.

Poultry. The 2025 pilot study by Mercer and colleagues in Frontiers in Veterinary Science (12:1527808, published 6 February 2025) states that ivermectin is not approved for use by any route in any poultry species in the US, that there is no tolerance for egg or meat residues, and that any use is extralabel. The tolerance list at 21 CFR 556.344(b) confirms the regulatory half of that: it names only bison, cattle, reindeer, sheep and swine. In that study, eight 78-week-old hens received injectable ivermectin topically over the jugular vein at 0.4 mg/kg every 7 days for two doses; egg yolk residues peaked at a geometric mean 3.54 ng/g at 6.6 days after the final dose, and residues persisted at low concentrations for up to 71 days. The authors' estimated egg yolk withdrawal intervals ranged from 57 days to 102 days depending on method, with the FDA tolerance limit method giving 81 days and the half-life multiplier method 96 days — and they state the study design does not meet EMA or FDA requirements for drug approval. More on why laying hens have no interval at all.

Horses. Every approved equine ivermectin dosage form substitutes a food-use prohibition for a withdrawal period, including the 1.87% paste (21 CFR 520.1192(e)(1)(iii)) and the meal (21 CFR 520.1194). And FDA's screwworm drug page, retrieved 28 September 2026, states that no medicated feeds containing ivermectin or doramectin are approved for any indication for cattle or wildlife in the US — a sentence limited to cattle and wildlife, since the swine slaughter withdrawal for the approved 5-day feed premix is a genuine exception.

Extra-label use: why the label interval no longer applies and FARAD must be consulted

Extralabel use is defined at 21 CFR 530.3(a) as use not in accordance with the approved labeling, including use in unlisted species, for unlisted indications, at other dosages, frequencies or routes, and deviation from the labeled withdrawal time. Part 530 implements the Animal Medicinal Drug Use Clarification Act of 1994 (Pub. L. 103-396), published at 61 FR 57743 on 7 November 1996 and effective 9 December 1996. Its scope provision, 21 CFR 530.1, limits it to use by or on the lawful order of a licensed veterinarian within a valid veterinarian-client-patient relationship, and 21 CFR 530.11(a) states that extralabel use by a lay person is not permitted except when under the supervision of a licensed veterinarian. Extralabel use in or on animal feed is not permitted at all under 21 CFR 530.11(b).

Where extralabel use is permitted in food animals, 21 CFR 530.20(a)(2) requires the veterinarian to make a careful diagnosis, establish a substantially extended withdrawal period supported by appropriate scientific information, maintain identification of the treated animals, and assure that no illegal residues occur. That clause is the origin of every extended interval you will see quoted for goats or poultry. Ivermectin itself is not on the prohibited list at 21 CFR 530.41(a). FARAD, the USDA-supported Food Animal Residue Avoidance Databank, is the service veterinarians use to obtain those extended-interval recommendations; a number from FARAD is a recommendation to a veterinarian, and this page does not reproduce FARAD outputs as regulatory intervals.

How a withdrawal is calculated, in outline

The outline is the same for every product. A tolerance and a target tissue are fixed — for ivermectin, the marker residue 22,23-dihydroavermectin B_1a and, in cattle, liver at 1.6 ppm under 21 CFR 556.344(b). Animals are dosed at the proposed label rate and route, tissues or milk or eggs are sampled over time, and a statistical method is applied to the depletion curve so that the interval covers a stated upper percentile of the population rather than the average animal.

The poultry study above is a useful illustration of how much the method choice moves the answer, because the authors ran four: the EMA 95/95 method with the limit of detection (0.03 ng/g) as the residue limit gave 102 days; the FDA 95/99 method using the limit of detection as the tolerance gave 81 days; the half-life multiplier method gave 96 days, which is ten times the observed 9.5-day terminal half-life in egg yolk; and the same EMA method with twice the assay's lower limit of quantification (0.15 ng/g) gave 57 days. Same data, a 45-day spread.

Recalculation also happens after approval. FDA reduced the IVOMEC Plus pre-slaughter withdrawal from 49 days to 21 days by supplemental approval announced at 79 FR 64114 on 28 October 2014, and for several years the regulation carried both figures for different sponsors — 21 days for one and 49 days for others in the 2014 amendment, and a residual 49-day entry for one sponsor as late as the amendment at 86 FR 14815 on 19 March 2021. The current eCFR text of 21 CFR 522.1193(e)(3) states a single 21-day figure with no sponsor split.

Residue testing: what USDA FSIS samples and what a violation triggers

Residue enforcement in meat and poultry sits with USDA's Food Safety and Inspection Service under the National Residue Program. FSIS Directive 10,800.1 sets out scheduled sampling and inspector-generated sampling of livestock and poultry carcasses at slaughter, and FSIS Directive 10,800.2 describes the in-plant screening tests and tissue sampling that inspection program personnel carry out, including sampling where there is reason to believe a residue may be present. Confirmatory testing is done in FSIS laboratories, and carcass disposition follows from the result.

On the consequence side, FSIS states on its Chemical Residues and Contaminants page that it posts a weekly Residue Repeat Violators List identifying producers with more than one violation on a rolling 12-month period, and that it shares violation data with EPA and FDA. FDA's own Drug Residues page describes its role in follow-up, including its compliance policy on illegal drug residues in animal-derived foods. In practical terms, the tolerance in 21 CFR 556.344 is the number a laboratory result is measured against; the withdrawal interval is the tool a producer has for staying under it.

Keeping records that will satisfy an inspector

The federal recordkeeping duties in Part 530 fall on the veterinarian, not the producer. Under 21 CFR 530.5(b), a veterinarian must keep all required extralabel-use records for 2 years or as otherwise required by Federal or State law, whichever is greater — so 2 years is a floor. Under 21 CFR 530.12, a drug dispensed for extralabel use must bear or be accompanied by labeling that includes the prescribing veterinarian's name and address, the established name of the drug, directions for use, any cautionary statements, and the veterinarian's specified withdrawal time. And 21 CFR 530.20(a)(2)(iii) requires the veterinarian to maintain identification of the treated animals.

For a producer, the useful discipline follows from those provisions rather than from a federal rule of its own: record the date of treatment, the individual animal or group identification, the product's exact proprietary name and application number, the strength, the route, the dose given, who administered it, and the calculated earliest date the animal may be shipped. Where the use was extralabel, keep the veterinarian's written withdrawal instruction with the treatment record, because the label interval is not the operative number in that case. Buyer and quality-assurance programs frequently ask for more than federal law requires; this page does not attempt to summarise individual scheme requirements.

Common mistakes: the wrong species, the wrong route, the repeat dose

The wrong species

The sheep drench regulation at 21 CFR 520.1195(e)(2)(iii) reads "For use in sheep only. Do not use in other animal species as severe adverse reactions, including fatalities in dogs, may result." The injectable regulation goes further and dictates the label sentence itself: 21 CFR 522.1192(d)(2) requires labeling to bear the precaution that the product should not be used in other animal species as severe adverse reactions, including fatalities in dogs, may result. Separately, the paste section 21 CFR 520.1192 covers two entirely different products: a 1.87% paste for horses with no withdrawal and a food-use ban, and a 0.153% paste for cattle with a 24-day withdrawal. Attaching "24 days" to a horse syringe, or "no withdrawal" to a cattle paste, inverts both.

The wrong route

For the same species and the same active ingredient, the cattle intervals are 24 days orally, 35 days by injection, 48 days by pour-on and 180 days for the bolus. Concentrations differ too — 10 mg/mL for the injection, 5 mg/mL for the topical solution (21 CFR 524.1193(a)) and 0.8 mg/mL for the sheep drench — so volume arithmetic carried across products is wrong twice over. Our page on the cattle pour-on goes through the 48-day figure in detail. The IVOMEC injection label also states that the product is not for intravenous or intramuscular use.

The repeat dose

Label withdrawal intervals are established for the labeled regimen. The cattle and swine doses are not interchangeable either: 200 mcg/kg subcutaneously in cattle against 300 mcg/kg in swine on the same IVOMEC label. Re-dosing, or dosing more often than the label provides, is extralabel by the definition at 21 CFR 530.3(a), and the label interval stops applying. The poultry data give a sense of the scale involved: two topical doses seven days apart left detectable yolk residues for up to 71 days.

How this page is maintained and dated

This page was compiled from primary sources and reviewed on 28 September 2026. Every interval above comes from the eCFR text of the relevant section of 21 CFR, from the current DailyMed structured product label with its revision date named, or from an FDA emergency use authorization fact sheet with its authorization date named. Where a figure is historical — the 49-day IVOMEC Plus withdrawal, or the split sponsor entries of 2014 and 2021 — it is labelled as superseded and kept only so readers recognise it in older material.

Two things determine when this page changes. The first is the regulation: 21 CFR 522.1192 was last amended at 88 FR 27699 on 3 May 2023, 21 CFR 522.1193 at 86 FR 57997 on 20 October 2021, 21 CFR 524.1193 at 89 FR 42360 on 15 May 2024, 21 CFR 520.1192 at 86 FR 14818 on 19 March 2021 and 21 CFR 520.1197 at 84 FR 39183 on 9 August 2019. The second is the application inventory: an Animal Drugs @ FDA search for ivermectin returned 53 applications on 28 September 2026, of which 46 were approved — 21 NADAs and 25 ANADAs — and 7 carried the status "Voluntary Withdrawn". Emergency use authorizations are time-limited by nature and are dated individually above.

Frequently asked questions

What is the ivermectin slaughter withdrawal for cattle?

It depends on the product. 35 days for the 1% injection (21 CFR 522.1192(e)(2)(iii)), 21 days for the ivermectin–clorsulon injection (21 CFR 522.1193(e)(3)), 48 days for the 5 mg/mL pour-on (21 CFR 524.1193(d)(3)), 24 days for the 0.153% oral paste (21 CFR 520.1192(e)(2)(iii)) and 180 days for the 1.72 g sustained-release bolus (21 CFR 520.1197(d)(3)).

How long after ivermectin can I sell the milk?

No approved US ivermectin product answers that question with a number, because no milk withdrawal time was established for any of them. The labels and regulations instead bar the use in female dairy cattle of breeding age. There is no compliant way to derive a discard period from the label.

What is the ivermectin egg withdrawal for backyard hens?

There is none on any US label, because ivermectin is not approved in poultry and there is no egg tolerance. The only published US estimates are from the 2025 pilot study described above, which put the egg yolk interval between 57 and 102 days depending on method — estimates from eight hens, which the authors state do not meet FDA or EMA requirements for approval. Any use in laying hens is extralabel and requires a veterinarian.

Is the withdrawal period for sheep really only 11 days?

For the approved 0.08% oral drench at the labeled 200 mcg/kg, yes — 11 days before slaughter, stated both on the DailyMed label (revised 10/2024) and at 21 CFR 520.1195(e)(2)(iii). The ACSRPC sheep chart, updated November 2024, records the same 11 days. That figure belongs to the drench used as labeled in sheep and to nothing else.

Do the screwworm emergency authorizations shorten the withdrawal?

No. Both cattle EUA fact sheets — 5 February 2026 for IVOMEC and 27 August 2026 for Bimectin — state a 35-day pre-slaughter period, and FDA's FOI summary for the first says it is the interval already established under NADA 128-409. The EUAs are in one respect stricter, excluding calves born to treated cows from veal production.

Is a withdrawal interval the same as a half-life?

No, and mixing them is the commonest error in this subject. A half-life describes elimination kinetics in one matrix; a withdrawal interval is a regulatory period built on a tolerance, a target tissue and a statistical method. The one place the two legitimately meet is the half-life multiplier method, which in the poultry study multiplied the 9.5-day egg yolk terminal half-life by ten to give 96 days.

Can I just use an animal product on a person?

FDA states in its consumer update on ivermectin and COVID-19, content current as of 5 April 2024, that animal ivermectin products are different formulations from those approved for humans, that their safety in humans is not known because they have not been tested in humans, and that medications intended for animals should never be used on people. Every product discussed on this page is labeled for animal use only and none is approved for human use.

Ivermectin Withdrawal Times: Meat, Milk and Egg Intervals From Every US Label