Alum definition according to wikipedia

The alums are a class of chemical compounds. Alums are double sulfate salts, with the general formula AM 2·12H 2O, where A is a monovalent cation such as potassium or ammonium and M is a trivalent metal ion such as aluminium or chromium(III).
Formula: KAl(SO4)2·12H2O
Soluble in: Water

Though there are many types of alum, potassium alum is the one commonly used for household purposes. It is also the one that is most commonly referred to as alum. The chemical formula for potassium alum is KAl (SO4)2.H2O. It is the hydrated form of potassium aluminum sulfate and it's nomenclature is potassium aluminum sulfate dodecahydrate. Potash alum is commonly called Alum | Picking Alum in English, Fitkari in Hindi, Phitkari in Urdu, Padikaram in Tamil, Patika in Telugu, Phatakadi in Gujarati, Phatikara | Patika in Kannada e.t.c

Alum is colorless in crystal form, 100 % pure alum block will be completely translucent. Alum is easily soluble in water and when heated it becomes porous. When you heat a small piece of alum block, it will keep on bubbling up, this is referred to as "Burnt Alum". Alum has astringent, antiseptic, antihemorrhagic, and anti bacterial properties making it very effective for treating many skin problems and has many beauty uses.
Sodium aluminum sulfate is a type of alum that is used in commercial baking powder .

*Traditional Uses: Alum has been used since ancient times in both Ayurvedic and Chinese medicine as it has many wonderful medicinal uses.

In Ayurveda,(system of medicine with historical roots in the Indian subcontinent) alum is added to many medicines and is used to treat a wide variety of diseases. It is given in small quantities internally for treating cough and diarrhea, alum boiled along with babul is used as a gargle for sore throat.

*Alum is also used for treating cracked heels, to stop bleeding and is also used as an external application for piles to reduce the inflammation.

• Alum is also very commonly used in skin care especially for skin tightening and skin lightening. It is used for treating acne and acne scars, prevent blackheads, lighten dark spots and dark circles, for vaginal tightening and for hair removal.
  *Alum Industrial Use: Alum is also used in leather tanning, fire proof textiles and as a dye fixer for textiles and for water treatment.
  *Types of alum commonly found:

1. Potassium Alum: This the type of alum that has been used in both ayurvedic and Chinese medicine for centuries. It has wide uses and is popularly used in home remedies and also has industrial uses is the type of alum that is referred to as fitkari or phitkari in India.

2. Ammonium Alum: The chemical formula for ammonium alumina sulfate is NH4(ALSO4)2.12 H2O. It is not widely used for industrial purposes but ammonium alum is inexpensive and non toxic so it is used as a deodorant, animal and bird repellent sprays, water purification, vegetable glue, dyeing and tanning

3. Sodium Alum: The chemical formula for sodium alum is NaAL(SO4)2.12H2O. Sodium alum is mainly used in food industry to increase acidity and give a tart taste. Sodium alum powder is added to biscuits as it helps in slow liberation of carbon dioxide which is essential for uniform browning of biscuits. It is also used as a mordant in dyeing, tanning, water purifying, engraving and waterproofing textiles.

4. Aluminum Sulfate: The chemical formula for aluminum sulfate is Al2(SO4)3. It is also referred to as a type of alum but is technically not an alum as usually alums have double sulfate salts. It is used in baking powder, antiperspirant and since it is highly acidic it is added to very alkaline garden soil to balance out the pH levels of the soil. It is also used for purifying water, to fix dyes while dyeing fabrics and in paper making.

5. Selenate Alum: Selenate alum form when selenium takes the place of sulfur forming selenate alum. It is a strong oxidizing agent and therefore is used as an antiseptic.

SIDE EFFECTS OF ALUM

Alum is taken internally as a medicine in both Chinese and ayurvedic medicine but only in very small amounts as it is toxic in large doses. I would suggest consuming alum as medicine only under expert guidance and never as a home remedy. When using alum as a deodorant try using it on alternate days instead of regularly as even regular external application might get absorbed into the blood stream. If you are experiencing any irritation after using alum, stop using it.

However, a variety of other products that you use daily , including deodorants and antacid medications , also contain aluminum salts , increasing your exposure .

The New York University Langone Medical Center reports that although small amounts of aluminum usually cause no harm , prolonged exposure or exposure to high levels can cause serious medical problems . Harmful exposure occurs over time, from eating foods that contain the food additive sodium aluminum phosphate or from living near aluminum mining. Short - term exposure , such as from breathing aluminum dust in the workplace , is also harmful . Aluminum toxicity affects the musculoskeletal system and brain , causing muscle weakness , bone pain , osteoporosis , delayed growth in children , altered mental abilities , dementia and seizures . LIVESTRONG.COM / Diseases and Conditions / Addiction and Recovery / Substance Abuse And also, Aluminum from your diet or healthcare product, can cause degeneration of nervous system tissue. It is possible that exposure to aluminum could lead to an increased risk of certain cancers, brain plaques or Alzheimer's Disease.

• Alum is the key ingredient used in styptic powder and pencils. The small amount absorbed into the blood stream from occasional use shouldn't cause health problems.
• Women are advised against using alum to tighten the vaginal wall. While the astringent property of the mineral may temporarily tighten tissue, use of the mineral in this manner may result in scarring, increased susceptibility to infection, and absorption of toxic chemicals.
• Alum is also used popularly for weight loss, external application of alum on the stomach is said to reduce belly fat but there is no scientific research proving this and please research well before using alum for weight loss.
• For water treatment 0. 05 % is the recommended dosage that does not have any side effects. If you experience any side effects after drinking water purified with alum, reduce the dosage even further.
• If you accidentally consumed alum in large doses seek medical help immediately.
  Lastly, Alum is either sold as fine powder under the name "Alum Powder" or in blocks like shown in the above picture. It is also called shaving alum in the shops. In some countries like Nigeria, india, China, Canada, Southafrica United state, Arab Emirates e.t.c they usually get alum in blocks and it can be stored for years and used. For home remedies, if you have got alum in block form, we can powder it in a mortar and pestle to a very fine powder, sieve and use. Alum is very cheap, so try to have a block of alum for treating a variety of diseases at home!

REFERENCES 1,2, 3