Educational information, not medical advice — ask your doctor or midwife.
Kali arsenicosum is a homeopathic remedy. It is made from potassium arsenite, an arsenic salt. The same salt was once sold as a medicine called Fowler's solution.
Homeopaths give it for dry, itchy, scaly skin and for restless worry at night. It is a minor remedy in homeopathy, not a leading one.
It is made by serial dilution. One drop of the starting liquid is mixed with water or alcohol, shaken, then diluted again and again. At 30C that step has been done 30 times, and essentially none of the arsenic is left.
The verdict: no human trials of this remedy have been published, and trials of homeopathy as a whole do not tell it apart from a dummy pill (placebo). Long use by homeopaths is not proof that a thing works. Arsenic itself is a poison, so low dilutions and old arsenic products are a real safety matter.
There is no known way for this remedy to act on the body. At 30C no arsenic is left to act.
Homeopathy works from a rule called 'like cures like'. Real arsenic can burn the skin and leave it dry and scaly. So homeopaths give a tiny dilution of it for skin that looks that way.
Some say the water keeps a 'memory' of what was in it. Lab work has not shown this to be true. Chemistry and physics offer no accepted route for plain water or a sugar pellet to carry an effect.
Any change people notice is best explained by time, by care and attention, and by the placebo effect (feeling better because you expect to).
It comes in the usual homeopathic forms:
Sugar pellets or tiny pills that melt under the tongue. Liquid drops in water and alcohol. Powders or tablets.
Low dilutions such as 3X or 6X may still hold arsenic. Common strengths sold to the public are 6C, 30C and 200C.
It is also found in mixed skin creams. Some 'combination' pills hold several remedies at once.
Fowler's solution was made in 1786 by Thomas Fowler, an English doctor. Doctors used it for more than a century for fever, asthma, skin disease and leukaemia (a blood cancer).
It was later dropped. Long use caused skin damage, skin cancer, nerve damage and other harm.
Homeopaths added the same salt to their remedy lists in the 1800s. It has stayed a small, second-rank remedy in that one tradition, used mainly for stubborn dry skin.
Some reactions to Kali arsenicosum 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 a doctor or a poison centre straight away if someone swallows Fowler's solution, a low arsenic dilution, or any arsenic product by mistake. Do this even if they look well.
Get urgent help for vomiting with watery diarrhoea, belly pain, a pounding or uneven heartbeat, fainting, numb or tingling hands and feet, or sudden muscle weakness.
See a doctor soon if a rash spreads, weeps, smells bad or comes with fever. Also see a doctor if your skin has not improved after two weeks, if you feel worn out for weeks on end, or if worry is keeping you awake. Tell your doctor about every remedy you take, even sugar pellets.
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 Kali arsenicosum 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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