Ivermectin

Is ivermectin safe?

Taken as labelled for parasitic infections, yes: it is one of the better-tolerated medicines we score. Stromectol tablets are usually a single dose, and in the label's studies of strongyloidiasis (threadworm) the most common side effects, dizziness and itching, each affected under 3% of people. The real risks come from doses well above the label, repeated dosing for weeks, and animal products. We score it 83, a little below doxycycline (86), mainly because of its overdose record.

Ivermectin was approved by the FDA as Stromectol on 22 November 1996. Its approved uses are narrow:

• Tablets for intestinal strongyloidiasis (about 200 mcg per kg, once) and onchocerciasis, or river blindness (about 150 mcg per kg, once, repeated every 3 to 12 months). Tablets are 3 mg and taken on an empty stomach with water.
• Soolantra 1% cream for the bumps and spots of rosacea (approved 2014).
• 0.5% lotion (Sklice and generics) for head lice, now sold over the counterOver-the-counterA medicine you can buy without a prescription, in a pharmacy or shop, with directions on the pack for safe use without a doctor.More in the glossary in the US.

Side effects at normal doses

For worm infections, side effects are usually mild: dizziness, itching, nausea, diarrhoea or tiredness. People treated for river blindness often get a Mazzotti reaction in the first days, with itching, rash, fever, swollen lymph nodes and joint pain. That is the body reacting to dying parasites rather than to the drug, and it is managed with fluids, antihistamines or steroids.

Two rare warnings stand out. People heavily infected with Loa loa (eye worm), found in parts of West and Central Africa, can develop a serious or fatal brain reaction, so anyone with significant exposure there should be tested first. And the label reports neurotoxicity, from drowsiness to coma and death, in a small number of people without that infection, including some on recommended doses. Most recovered once the drug was stopped.

Ivermectin for COVID-19: what regulators and trials found

Laboratory studies found that ivermectin could block the virus that causes COVID-19, but the EMA noted on 22 March 2021 that this needed concentrations much higher than authorised doses reach. It concluded the data did not support use outside well-designed trials. The FDA said it had not authorised or approved ivermectin for COVID-19 and warned that large doses can be dangerous; that consumer page has since been removed from fda.gov.

The large trials since then are consistent:

Trial	People	Result
TOGETHER (NEJM, 2022)	1,358 on ivermectin or placebo	Hospital or prolonged emergency care in 14.7% vs 16.3%, no clear difference
COVID-OUT (NEJM, 2022)	1,323 analysed	No effect on the main outcome
ACTIV-6 (JAMA, 2022)	1,591 completed	Recovery 12 vs 13 days, not a meaningful difference
ACTIV-6 higher dose (JAMA, 2023)	1,206	11 days in both groups

These trials also showed that short courses near the label dose were well tolerated.

Animal products and poisoning

Demand during the pandemic led some people to take horse and cattle pastes, drenches and injections. These contain far more ivermectin per dose and are not made for humans. At the Oregon Poison Center, 37 people needed medical care for ivermectin toxicity between 14 August 2021 and 31 January 2022: 21 were admitted to hospital and one died. Thirty had neurological symptoms such as confusion, and 17 had taken veterinary products, at higher doses and with more confusion than those on tablets. People who took normal-sized doses daily for weeks also became ill, though less severely. In California, ivermectin calls to poison control rose steadily through 2021.

Without a prescription in some US states

Several US states now let pharmacists dispense ivermectin tablets without a prescription. Texas House Bill 25, passed on 27 August 2025, took effect in December 2025, and news reports name Arkansas, Idaho, Louisiana and Tennessee as earlier states. Bills were filed in more states in 2026. A change in sales rules does not change the label: the approved doses and uses stay the same. Anyone unsure which product or dose fits their situation should talk to a doctor or pharmacist.

How we scored it

Dependence (95), track record (95), serious side effects (85) and interactions (85) are strong for a single-dose drug with decades of mass use. The overdose marginOverdose marginHow far a normal dose is from a harmful one. A wide margin means an accidental extra dose is unlikely to cause serious harm.More in the glossary (68) is the weak point, because large or repeated doses, especially of veterinary products, cause neurotoxicity. Regulatory warnings (75) reflect regulator statements on COVID-19 misuse rather than problems with labelled use.