What Are the Most Common Ivermectin Side Effects?

Ivermectin is a drug that kills certain parasitic roundworms. Common ivermectin side effects include dizziness and gastrointestinal upsets. Some other adverse effects can occur, and many of these are associated with the death of the roundworms rather than directly with the drug.

Roundworms that ivermectin can target include the threadworm that causes strongyloidiasis and the parasite that causes onchocerciasis, a disease also known as rive blindness. In the case of strongyloidiasis, the worms live in the intestinal tract, but with onchocerciasis, the worms travel around the body and reside under the skin. Ivermectin can also treat scabies or lice infestations.

A typical dose of ivermectin is one tablet on an empty stomach. Repeat doses are necessary in the treatment of onchocerciasis and may also be required for some strongyloidiasis infections. Although the drug kills the adult threadworms of strongyloidiasis, it only kills the immature worms that cause onchocerciasis. The most common ivermectin side effects are gastrointestinal in nature, with the patient experiencing diarrhea and feelings of nausea. Dizzy spells can also result from taking the drug.

While not directly attributable to the drug, the death of the worms in the body can also provoke some other ivermectin side effects. In the three days directly after taking the drug, itchiness, fever, and skin rash can occur. Muscle aches and headaches can also be ivermectin side effects. Even though a doctor's advice is necessary if these side effects occur, most of the time, the issues are easily soothed with a painkiller or an antihistamine drug. The risk of these common adverse reactions correlates with the level of infection and the amount of worms present in the body.

Patients under ivermectin treatment may also experience vomiting, pain in the stomach area, or constipation. The chest may also hurt, and the drug may cause one area of the body to tremor uncontrollably. Unusual tiredness or loss of strength can also occur.

Onchocerciasis treatment side effects can differ. With this disease, administration of the drug can result in swelling of the joints and of the lymph glands, along with faster-than-usual heartbeats. The eyes can also be affected and can become swollen, red, and painful. Swelling can also occur in the extremities of the body and in the face. Many people, however, suffer no side effects from taking the ivermectin medication or only experience the milder, more common symptoms.