What is Lac caninum?

Lac caninum is a homeopathic remedy. It is made from dog's milk. Homeopaths give it most often for a sore throat that moves from one side to the other.

They also use it for breast pain and for feeling low about yourself. The milk is diluted step by step, with shaking at each step. At 30C, the usual strength, no dog's milk is left in the pill.

Trials have not shown that it works better than a dummy pill. Long use in a tradition is not proof that a thing works. This page scores the trial evidence and the traditional record apart.

How does Lac caninum work?

There is no known way for this remedy to act on the body. Homeopathy rests on two old ideas. The first is 'like cures like': a thing that causes symptoms in a well person is said to treat those same symptoms in a sick one.

The second idea is that the shaking at each step leaves a trace of the milk behind. Chemistry does not support that idea. At 30C no dog's milk is left, so there is nothing there to act.

Any change you feel is most likely down to time, to the care you get, or to the placebo effect (feeling better because you expect to).

What forms does Lac caninum come in?

Most people take small sugar pellets that melt under the tongue. Liquid drops in alcohol and water are also sold.

Common strengths are 6C, 30C and 200C. The 'C' means the mix was made one part in 100 each time. The number tells you how many times that was done.

Some makers sell it in kits or blend it with other remedies. Read the label so you know the strength you have.

Where it comes from:

Lac caninum came into homeopathy in the United States in the 1800s. Samuel Swan, an American homeopath, first prepared it. Writers such as Reuben Ludlam then listed the symptoms it was said to match.

Dog's milk also turns up in older Western folk writing, long before homeopathy began. That older thread is separate and says nothing about the remedy today.

It now sits in most homeopathic materia medicas (reference books of remedies). It is well known in that tradition, but it is not one of the most used remedies.

What does Lac caninum help with?

• Sore throat that keeps switching sides: This is the picture homeopaths link most closely with Lac caninum. The throat is said to hurt on the right, then the left, then back again. No human trial has tested the remedy for sore throat, so this rests on case notes alone. A sore throat with high fever, or one that makes it hard to swallow or breathe, needs a doctor, not a pellet.
• Tonsillitis (swollen, sore tonsils): Homeopaths have used it for red, swollen tonsils with pain that moves side to side. There is no trial evidence for this use. Some tonsil infections are caused by bacteria and need antibiotics. If a doctor has prescribed them, take them.
• Breast pain and swelling: Old homeopathic texts list sore, heavy, tender breasts among its main signs. No published human trial supports this use. A new lump, a change in the skin, fluid from the nipple, or a hot red breast with fever needs a doctor's check first.
• Drying up breast milk when weaning: This is a long-standing use in homeopathic books, given when a parent wants milk flow to stop. There is no trial evidence that it changes milk supply. Talk to your midwife, health visitor or doctor about weaning. They can also help if your breasts become hard, hot or painful.
• Migraine that shifts from one side to the other: Homeopaths report giving it for head pain that swaps sides from day to day. No trial has tested it for migraine. Migraine has treatments that are backed by good research. Ask your doctor about those.
• Low self-worth and fear of failing: In homeopathic writing the remedy is tied to people who feel small, dirty or sure they will fail. This is a symptom picture from case notes, not a tested treatment. If low mood or low self-worth is weighing on you, speak to your doctor or a therapist.

What are the side effects of Lac caninum?

• Nothing at all: most people feel no direct effect
• Mild stomach upset or loose stools, now and then
• A short flare of your symptoms, which homeopaths call an aggravation
• Milk sugar (lactose) in the pellets may upset you if milk sugar bothers you
• A mild rash or itch, which is rare
• Alcohol in the liquid drops, which matters if you avoid alcohol
• The biggest risk is not a side effect: it is waiting too long to get real care

Good to know:

At 30C there is no dog's milk left in the pill. So direct harm from the remedy is very unlikely.

Most reports of upset are mild and pass on their own. Very low strengths such as 1X to 3X may still hold milk protein. If you are allergic to milk, avoid those.

Tell your doctor and pharmacist what you take, even if it is 'only' a homeopathic pill.

How much Lac caninum should you take?

• Recommended daily: No dose has been set by research, because no trial has found an effect to dose for. Homeopaths commonly suggest three to five pellets of 30C under the tongue, up to three times a day. Some give a single dose of 200C and then wait to see what happens. Follow the label on the pack you bought. Taking more is not thought to help, even within homeopathy. Stop once you feel better.
• Best time of day: Any time of day. Homeopaths often ask you to keep your mouth clear of food, drink, toothpaste and strong mint for about 15 minutes before and after a dose.
• With or without food: Between meals, on a clear mouth. Let the pellets melt under your tongue rather than swallowing them with water.
• Time to effect: Homeopaths expect a change within hours to a day for a short illness. There is no trial evidence to back that timing. If your symptoms get worse at any point, stop waiting and get medical help.
• How long to take it: Think in days, not months. For a short illness such as a sore throat, homeopaths usually stop within two or three days. If you are no better after 48 hours, or you are getting worse, see a doctor. Do not keep taking it in place of care that works.