Educational information, not medical advice — ask your doctor or midwife.
Latrodectus mactans is a homeopathic remedy made from the black widow spider. Homeopaths have given it for sharp chest pain that spreads down the arm. It comes as sugar pills, granules or liquid drops.
It is made by serial dilution: the starting material is watered down again and again, with shaking at each step. At the usual 30C strength, no measurable trace of the spider is left. What you take is sugar, or alcohol and water.
Trials have not told this remedy apart from a placebo (a dummy pill with no medicine in it). Long use in homeopathy is a record of custom, not proof that it acts in the body. Chest pain can mean a heart attack, so do not treat it at home.
No one has shown a way this remedy could act in the body.
Homeopathy rests on an old idea called like cures like. A thing that causes symptoms in a well person is said to ease the same symptoms in a sick person. A real black widow bite causes gripping chest and belly pain, so the diluted spider is given for pain that feels like that.
The next step is the problem. The material is watered down so far that none of it is left. Homeopaths say the water keeps a trace of the original, but chemistry and physics do not support that idea.
You will see it as small sugar pills, tiny granules, or liquid drops in alcohol and water.
Strengths are written as a number and a letter, such as 6C, 30C or 200C. The bigger the number, the more it has been watered down. 30C is the strength most often sold in shops.
Low strengths and mother tinctures are not shop products and are not for home use. Sugar pills usually contain lactose (milk sugar). Drops usually contain alcohol.
The remedy entered homeopathic practice in the United States in the late 1800s. Homeopaths gave the watered-down spider to healthy people and wrote down what they felt. Those notes became the symptom picture still used today.
It has always been a small, rarely used remedy. Its name in homeopathic books is tied mainly to chest pain.
Some reactions to Latrodectus mactans need urgent care. Call your local emergency number or go to an emergency department straight away — do not wait to see whether it passes.
Call emergency services now if you have chest pain that lasts more than a few minutes, spreads to your arm, neck or jaw, or comes with cold sweat, sickness or trouble breathing. Do the same if someone has collapsed or cannot speak properly.
See a doctor within a day if you get chest tightness on walking or climbing stairs, or if you feel your heart racing or skipping.
Go to hospital after any spider bite that brings cramping pain, heavy sweating, a rigid belly or a rapid heartbeat.
See a doctor if cramps, pain or breathlessness keep coming back, or if any symptom you were treating at home is getting worse.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
Reviewed by the HealisticMD editorial team How we grade evidence →
The published evidence for Latrodectus mactans is weak or absent. That usually means no controlled trial has tested it, not that a trial found it ineffective — the two are different, and we grade only what has been published.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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