Educational information, not medical advice — ask your doctor or midwife.
Lac felinum is a homeopathic remedy made from cat's milk. Its Latin name is Felis catus (milk). You may also see it sold as Cat's milk.
Homeopaths use it most often for eye trouble. Think sore, tired or burning eyes, or pain around the eye. A few also give it for a one-sided headache or a raw sore throat.
The milk is watered down and shaken again and again. This step-by-step watering down is called serial dilution. At 30C, the usual strength, none of the cat's milk is left in the pill.
Tests in people do not show that it works better than a dummy pill (placebo). Long use by homeopaths is not proof that a remedy works. This page reports both facts side by side.
No one has shown how it could work. That is the honest answer.
Homeopathy rests on two old ideas. The first is "like cures like". A thing that causes symptoms in a well person is used to treat the same symptoms in a sick person.
The second idea is that shaking each watered-down step makes the remedy act more strongly. This does not fit what we know about chemistry. At 30C there is nothing of the milk left to act on your body.
So any change people notice is most likely a placebo effect. That means you feel better because you expect to, or because the problem was easing anyway. Time, rest and a caring listener all play a part.
It comes in a small number of simple forms.
Most people get tiny sugar pellets or small round pills that melt under the tongue. Liquid drops in alcohol and water are also sold.
Common strengths are 6C, 30C and 200C. Some homeopaths use LM (also written Q) strengths, given as drops in water.
Lac felinum is a rare remedy. Few high-street shops stock it. It is usually ordered from a pharmacy that makes homeopathic remedies, often after a homeopath asks for it.
The remedy dates from homeopathy in the United States in the late 1800s.
The homeopath Samuel Swan is credited with the first proving. A proving is when healthy people take a remedy and write down every symptom they notice.
Swan's notes point mostly to the eyes. Later writers copied those notes and added a few symptoms of their own.
It has stayed a small, rarely used remedy. It sits in the group of "milk remedies" that some homeopaths work with, alongside remedies made from dog, horse and human milk.
Get help the same day if you have sudden eye pain, a red painful eye, blurred or lost sight, flashes of light or a shower of new floaters. Loss of sight in one eye is an emergency.
See a doctor urgently for the worst headache of your life, or a headache with fever, a stiff neck, confusion, weakness or a rash.
Get urgent help for a sore throat with trouble breathing, trouble swallowing your own spit, or drooling.
Book a normal appointment if eye strain, headaches or a sore throat last more than two weeks, keep coming back, or stop you doing everyday things.
Stop the remedy and speak to a doctor if you get a rash, itching, swelling of the lips or face, or wheezing after taking it.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
One email with the summary. We'll also send a short weekly evidence update — unsubscribe any time.