Ivermectin Side Effects: What’s Normal and What’s Not

Ivermectin Side Effects: What’s Normal and What’s Not

Ivermectin is a widely used antiparasitic medication that has proven effective in treating various infections caused by worms, mites, and lice. Originally developed for veterinary use, Iverheal 12 has since become a staple in human medicine for conditions like scabies, strongyloidiasis, and onchocerciasis (river blindness).


Despite its proven benefits, like all medications, ivermectin can cause side effects. Understanding which side effects are normal and which may require medical attention is key to using this drug safely and effectively.


What Is Ivermectin?

Ivermectin works by interfering with the nervous system of parasites, causing paralysis and death of the organisms. In humans, it is most commonly prescribed as an oral tablet, though topical formulations are also available for skin conditions like scabies and head lice.


Its FDA-approved uses include:


Common (Normal) Side Effects of Ivermectin

Most people tolerate ivermectin well, but mild side effects may occur, especially during the first few days of treatment. These are generally short-lived and not cause for alarm.


✅ 1. Dizziness

Some users report feeling lightheaded or dizzy after taking ivermectin. This may be related to the medication’s effect on blood pressure or due to the body's response to the dying parasites.


✅ 2. Nausea or Upset Stomach

Mild gastrointestinal symptoms like nausea, abdominal pain, and diarrhea are common. These usually resolve within a few days without the need for treatment.


✅ 3. Fatigue or Drowsiness

A temporary feeling of tiredness or drowsiness can occur. It’s best to avoid driving or operating heavy machinery until you know how the drug affects you.


✅ 4. Skin Itching and Rash

Mild itching or a rash may appear, particularly when treating skin infestations like scabies. This is often due to the immune system reacting to dead mites or parasites.


✅ 5. Headache

Headaches can happen shortly after taking ivermectin. These are usually manageable with hydration and over-the-counter pain relievers.


Uncommon but Concerning Side Effects

While rare, some side effects may be more severe and warrant medical evaluation, especially if persistent or worsening.


⚠️ 1. Severe Skin Reactions

Although itching is common, intense or worsening rashes, blistering, or peeling may indicate an allergic reaction. Seek medical help if this occurs.


⚠️ 2. Swelling of the Face or Limbs

Swelling, especially around the eyes, lips, or tongue, can be a sign of a serious allergic reaction (angioedema). This requires immediate medical attention.


⚠️ 3. Rapid Heartbeat or Irregular Pulse

Heart palpitations, chest discomfort, or an irregular heartbeat may indicate an adverse reaction and should be evaluated promptly.


⚠️ 4. Neurological Effects

In rare cases, ivermectin may cause confusion, tremors, or seizures, especially when taken in high doses or when used improperly. These are not normal and demand urgent medical care.


⚠️ 5. Severe Eye Problems (for Onchocerciasis Patients)

When treating onchocerciasis, inflammation in the eye can result from dying microfilariae. Symptoms include red eyes, blurred vision, and eye pain. These effects require close monitoring. You can also visit dosepharmacy to get more information about ivermectin.


Mazzotti Reaction: A Special Consideration

A unique and sometimes intense reaction, called the Mazzotti reaction, can occur in individuals being treated for onchocerciasis. This is not a direct drug side effect but a response to the rapid killing of the microfilariae (larval worms).

Symptoms include:

While alarming, this reaction is usually temporary and managed with antihistamines or corticosteroids under medical supervision.


Ivermectin Overdose: What Happens If You Take Too Much?

Taking more ivermectin than prescribed can increase the risk of serious side effects, particularly those affecting the nervous system.

Symptoms of overdose include:

Overdose cases are rare but potentially life-threatening and require immediate emergency care.


Who Is at Higher Risk of Side Effects?

Certain individuals may be more vulnerable to ivermectin side effects, including:


Precautions to Take While Using Ivermectin

To reduce the risk of side effects:


Ivermectin in COVID-19: A Word of Caution

During the COVID-19 pandemic, ivermectin was promoted by some as a potential treatment. However, leading health organizations including the FDA, CDC, and WHO have stated that ivermectin is not approved for COVID-19 treatment and its inappropriate use has led to cases of overdose and hospitalization.


Always consult a healthcare provider before using ivermectin for any condition not officially approved.


When to Call a Doctor

Contact your healthcare provider immediately if you experience:


Final Thoughts

Ivermectin is a highly effective and generally safe medication when used properly for parasitic infections. Mild side effects like dizziness, nausea, and itching are normal and typically go away on their own. However, more serious reactions—such as allergic responses, neurological symptoms, or severe swelling—should not be ignored.


By understanding what to expect and when to seek help, patients can use ivermectin confidently and responsibly. Always follow your doctor’s instructions and never exceed the recommended dosage.