Conditions and symptoms
What Is the Mazzotti Reaction? River Blindness Treatment
Mazzotti reaction · say it: mah-ZOT-ee ree-AK-shunAlso written: Mazzotti-type reaction, Mazzotti test reaction, post-treatment reaction
Short answer
The Mazzotti reaction is an inflammatory reaction after treatment for river blindness or similar worm infections, as many worm larvae die at once.
What it means
The Mazzotti reaction happens after treatment for onchocerciasis (river blindness) and some related worm infections. As the medicine kills large numbers of microfilariae (tiny worm larvae) in the skin, the body reacts to the dying larvae with inflammation. Symptoms can include itching, rash, fever, headache, joint and muscle pain, swollen, tender glands, swelling of the skin, a fast heartbeat and dizziness on standing. It usually appears within a day or two of treatment. Severe symptoms, such as fainting or trouble breathing, need urgent medical help.
Ivermectin and diethylcarbamazine labels describe it so that people and health workers know it can happen and is linked to the treatment working, especially in people with heavier infections. It is usually short-lived. Labels also note eye symptoms and the need for care in people with very high levels of a related worm, Loa loa.
The Mazzotti reaction is not an allergy to the medicine itself; it is a reaction to the dying parasites. It is named after Luigi Mazzotti, the doctor who described it.
Where you may see it
- The 'Adverse Reactions' and 'Warnings' sections of ivermectin labels
- Mass treatment programme information for communities
- Tropical medicine clinic notes
📄 How it looks on a report
Mazzotti-type reactions, including pruritus, rash, fever and lymph node tenderness, may occur after treatment of onchocerciasis.
🙅 What it does not mean
- It does not mean you are allergic to the medicine.
- It does not mean the treatment has failed; it often happens because the larvae are being killed.
- It is not something to ignore if it becomes severe; dizziness, fainting or breathing trouble need urgent care.
🎯 Check yourself
Which of these is the right meaning of “Mazzotti reaction”?
🗒️ Questions to ask your doctor
💊 Medicines whose labels mention “Mazzotti reaction”
Plain-English explanations of each medicine, from its official FDA label.
- Ivermectin
An antiparasitic medicine, sometimes called a worm-killing medicine (anthelmintic), that the FDA lists as an antiparasitic and pediculicide
🔗 Read more from trusted sources
- “Mazzotti reaction” on MedlinePlus ↗
US National Library of Medicine
Seeing this word on your own report? Get every line of it explained, free.
Explain my report🧩 Related words
🔎 Look up another word
More words: conditions and symptoms
General information about a medical word, not advice about your own results. Ask the clinician who ordered the test what it means for you.