Alum, popular known as Fitkari, is a commonly used name of chemical compound: the potassium double sulfate of aluminium. Alum is well known for water purification, after shave treatment and preventing evil influences. Alum powder is used in a wide range of applications from deodorants through to making pickles as it is capable of inhibiting bacterial growth. Alum powder is used in leather tanning, dyeing, baking powder and fireproof textiles.
Alum has a lot of medical and health benefits. But we need to make sure that only a pinch is used when taken internally. Also, it is recommended not to use alum externally on skin on daily basis. Larger intake of alum has negative side effects for the health. So it is very important to keep the alum stone and alum powder away from children.
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Names of Alum in different Indian languages:

Most of you might be interesting to know what is alum in your regional language. Here you go.

Alum in Hindi - Fitkari | Phitkari.
Alum In Tamil - Patikaram or Padikaram.
Alum In Telugu - Patika.
Fitkari in Malayalam - Fatakadi or Phatakadi.
Fitkari In Kannada - Patika.
Fitkari In Gujarati - Phatakadi.