What is Aethusa cynapium?

Aethusa cynapium is a single homeopathic remedy. Its source plant is fool's parsley, a wild weed that looks like garden parsley but is poisonous. Homeopaths reach for it most often for babies who throw up milk soon after a feed.

The remedy is made by watering the plant extract down again and again, with hard shaking at each step. This is called serial dilution. At the common 30C strength, not one molecule of the plant is left.

Here is the plain verdict. Trials have not shown this remedy doing more than a dummy pill. Long use inside homeopathy is a record of custom, and custom is not proof that something works.

How does Aethusa cynapium work?

There is no known way for a 30C pellet to act on the body, because nothing from the plant is still in it.

Homeopathy rests on two ideas. The first is "like cures like": a substance that causes symptoms in a well person is said to ease those same symptoms in a sick one. The second is that watering a substance down makes it act more strongly.

Neither idea fits what we know about the body or about chemistry. Homeopaths answer that the water keeps a "memory" of the plant. No test that other scientists can repeat has ever shown such a memory.

So what do people feel when they take it? Most likely the placebo effect, the normal path of a short illness that was going to settle anyway, and the calm of a long, careful talk with a practitioner.

What forms does Aethusa cynapium come in?

Sugar pellets are the usual form. They come marked 6C, 30C or 200C, and you let them melt under the tongue. Liquid drops in water and alcohol are also sold.

Low strengths such as the mother tincture, 1X or 3X are a separate case. These can still hold plant matter from a poisonous plant. Only use them if a qualified practitioner has told you to.

Check the label before you buy. A bottle that says "tincture" or "1X" is not the same thing as a 30C pellet.

Where it comes from:

Fool's parsley grows wild across Europe and has spread to North America. People have died after picking it by mistake for parsley or wild carrot. It has never been a food or a herbal medicine.

Homeopaths added it in the 1800s after a "proving". In a proving, healthy people take a substance and write down every feeling they notice. Aethusa has stayed in homeopathic reference books since then, mostly as a children's remedy.

What does Aethusa cynapium help with?

• Vomiting of milk in babies: This is the classic homeopathic picture for Aethusa: a baby takes milk, brings it straight back up in curds, then wants to feed again. No trial has tested the remedy for this. A baby who keeps vomiting needs a doctor the same day, because babies lose body fluid fast.
• Milk intolerance in infants: Homeopathic texts describe Aethusa for infants who seem unable to keep any milk down. Real milk protein allergy and lactose problems are medical diagnoses with tested treatments. There is no evidence that Aethusa changes either one.
• Summer diarrhoea in children: Old homeopathic books list Aethusa for watery diarrhoea with vomiting in hot weather. The tested treatment for this is oral rehydration salts, a drink that replaces lost water and salts. Do not use Aethusa in place of them.
• Weakness and sleepiness after vomiting: Homeopaths use Aethusa when a child falls into an exhausted sleep after being sick. There is no trial evidence for this. Sleepiness that you cannot rouse a child from is an emergency, not a remedy picture.
• Stomach upset during teething: Some homeopathic guides suggest Aethusa for babies who are sick to the stomach while teething. Teething itself does not cause vomiting or diarrhoea, so those symptoms need a proper look from a doctor. Evidence for the remedy here is absent.

Which foods are rich in Aethusa cynapium?

Fool's parsley is easy to confuse with real parsley in a garden or hedgerow, so never gather look-alike leaves for the kitchen.

What are the side effects of Aethusa cynapium?

• No direct effects are expected from 30C pellets, because they hold no plant material
• Sugar from the pellets, which matters if you count carbohydrate closely
• Alcohol in liquid drops, which matters for children and for anyone avoiding alcohol
• A short worsening of symptoms, which homeopaths call an aggravation and which has not been shown to be real
• Poisoning signs such as burning in the mouth, being sick, dizziness, muscle weakness or trouble breathing, if a low strength or the raw plant is swallowed
• Harm from delay, when a real illness goes untreated while the remedy is tried

Good to know:

For a 30C or 200C product, direct side effects are very unlikely. The pellet is sugar. The real risks sit elsewhere: swallowing a low-strength product that still holds this poisonous plant, and using the remedy instead of care that a sick baby or child actually needs.

How much Aethusa cynapium should you take?

• Recommended daily: There is no established or tested dose, because there is no active plant material in the usual strengths to measure. Homeopathic books commonly suggest a 30C pellet given a few times a day for a short acute spell. Those numbers come from custom, not from trials.
• Best time of day: No time of day has been shown to matter. Homeopaths usually space doses through the day during a short illness.
• With or without food: Homeopaths advise taking pellets on a clean mouth, about 15 minutes away from food, drink, mint or toothpaste. This is a custom of the tradition, not a tested rule.
• Time to effect: No effect beyond placebo has been shown, so no honest time frame can be given. Homeopathic texts claim a response within hours in acute cases.
• How long to take it: Homeopathic practice is to stop as soon as things improve, and to stop anyway if nothing has changed after a day or two. For a vomiting baby, a day or two is far too long to wait. Get medical care first and reassess from there.