The side effects listed in the prescribing information for ivermectin include dizziness, itching, nausea, diarrhea, belly pain, tiredness, sleepiness and rash. Rarer but serious reports include changes in consciousness or confusion, seizures, liver problems and severe skin reactions, and people treated for river blindness can have a reaction to dying parasites called the Mazzotti reaction.

Ivermectin is a prescription antiparasitic. The 24 mg scored ivermectin tablet Get It Prescribed provides is a compounded preparation that is not FDA-approved and is not a generic of or substitute for the brand-name 3 mg ivermectin tablet. Whether to prescribe it, and at what dose, is decided by a licensed provider who reviews your health history first. This article is general education, not a substitute for that review.

How ivermectin works

Ivermectin binds to glutamate-gated chloride channels found in the nerve and muscle cells of certain parasites, causing paralysis and death of the organism. Because mammals largely lack these channels and the drug does not readily cross the human blood-brain barrier, it is selective for the parasite rather than the host. You can read more about the science on the ivermectin medication page and see how the overall service works at how it works.

Common side effects

The prescribing information for the brand-name ivermectin tablet lists the side effects reported in clinical studies of people treated for intestinal strongyloidiasis. Each was reported in fewer than 3 in 100 patients:

• Dizziness, sleepiness, vertigo or tremor
• Nausea, vomiting, diarrhea, constipation, loss of appetite or belly pain
• Tiredness or weakness
• Itching, rash or hives

Tell your provider about any side effect that bothers you or does not go away. The prescribing information says the brand-name tablet should be taken on an empty stomach with water; follow the directions on your own prescription label.

The Mazzotti reaction

When ivermectin is used to treat onchocerciasis, the die-off of microfilariae can trigger fever, rash, swollen lymph nodes, and joint pain — known as a Mazzotti reaction. The prescribing information describes these as the body's reaction to dying parasites, and notes they would not be expected in people treated for strongyloidiasis. The prescribing clinician watches for them when relevant. Read more about this use in onchocerciasis and river blindness.

Neurologic effects and who needs extra caution

The prescribing information describes rare reports of changes in consciousness, ranging from drowsiness to stupor or coma, along with confusion and disorientation, including in people who did not have Loa loa infection; very rarely these have been fatal. Separately, people with onchocerciasis who are also heavily infected with Loa loa have rarely developed a serious brain reaction (encephalopathy). Other rare reports since the medicine was marketed include seizures, low blood pressure on standing, worsening asthma, liver inflammation and severe skin reactions such as Stevens-Johnson syndrome. Anyone with a history of central nervous system conditions, or significant time spent in West or Central Africa, should discuss this directly with their provider before treatment, since it affects candidacy.

Table: what the prescribing information reports

| Category | Examples | What to do | |---|---|---| | Reported in clinical studies (each in fewer than 3 in 100 patients) | Dizziness, itching, nausea, diarrhea, tiredness, rash | Tell your provider, especially if it persists | | Mazzotti reaction (river blindness treatment only) | Itching, rash, fever, joint pain, swollen lymph nodes | Follow your clinician's instructions; report severe reactions | | Rare but serious | Confusion or changes in consciousness, seizures, severe skin reactions, liver problems, worsening asthma | Seek medical attention promptly |

When to contact your provider

Reach out if side effects do not improve, worsen, or if you notice signs of an allergic reaction such as swelling, difficulty breathing, or a spreading rash. Because ivermectin can interact with other medications, always keep your provider updated — see our overview of drug interactions and who should not take these medications.

Reporting and follow-up

If you experience an unexpected reaction, tell your prescribing provider so it can be documented and, if appropriate, reported through FDA MedWatch. Understanding pricing and availability for follow-up visits can help you plan next steps if adjustments are needed. For background on the medicine itself, see what ivermectin is and what it is used for.

Related questions

What are the side effects of ivermectin?

The prescribing information lists dizziness, itching, nausea, diarrhea, belly pain, tiredness, sleepiness and rash among the side effects reported in clinical studies, each in fewer than 3 in 100 patients. Rare but serious reports include confusion or changes in consciousness, seizures, liver problems and severe skin reactions. Tell your provider about any side effect, and get urgent care for confusion, trouble breathing or a spreading rash.

Can I take ivermectin with food?

The prescribing information says the brand-name ivermectin tablet should be taken on an empty stomach with water, since food can significantly increase absorption. Do not change how you take it without checking with your prescribing provider, since your dose was calculated with a specific administration method in mind.

Is dizziness after ivermectin dangerous?

Dizziness is one of the side effects most often reported in the prescribing information. However, if dizziness is severe, persistent, or paired with confusion or trouble standing, contact your provider promptly, since these can occasionally signal a more significant neurologic reaction that needs evaluation.

Can side effects mean the medication isn't working?

No. Side effects reflect how your body responds to the drug (or, in parasitic infections, to dying organisms), not a measure of effectiveness. Only your provider, using your specific clinical picture, can assess whether treatment achieved its intended purpose.

Do side effects mean I should stop taking it?

Do not stop or change your dose without talking to your provider first. Report side effects so they can advise whether to continue, adjust, or discontinue treatment based on your full medical picture.

Sources

• DailyMed: ivermectin tablet prescribing information — prescribing information, adverse reactions, and warnings.
• MedlinePlus — Ivermectin — patient-friendly summary of side effects and precautions.
• CDC: Clinical Overview of Strongyloides — background on a labeled indication for ivermectin.