Alum (Aluminium Sulphate) is a non-toxic solid compound widely used in water treatment plants to clarify drinking water. Its primary function is to aid coagulation and flocculation, which helps remove suspended particles and impurities. In lake management, alum reduces phosphorus levels, limiting algae growth and improving water quality by controlling phosphorus release from lake bottom sediments. This process enhances water clarity and reduces the frequency of harmful algal blooms, making water safer for ecosystems and human use. This article will explore alum, its benefits, dosage and precaution tips.
Last updated on : 17 Oct, 2025
Read time : 12 mins

Alum is an inorganic chemical compound generally made up of a hydrated double sulphate salt. It is composed of a trivalent metal (like aluminium) and a monovalent cation (such as sodium, potassium, or ammonium). The most common form used in traditional remedies and cosmetics is Potassium Aluminium Sulphate, often referred to as Potassium Alum or Potash Alum.
The general chemical formula for this common alum is KAl(SO4)2⋅12H2O. Alum is typically sold as white or sometimes red crystalline stones or powder, often known by its Hindi name, Fitkari (Phitkari).
| Feature | Details |
| What is Alum? | Alum is a chemical compound often used in water purification, medicines, cosmetics, and as a pickling agent. |
| Origin | Alum occurs naturally in minerals such as alunite and bauxite and can be found worldwide. It has been used for centuries in various industries. |
| Common Use | Alum is commonly used for water purification, as an astringent, in medicines, deodorants, and pickling foods. |
| Chemical Composition | Alum refers to a group of double sulphate salts containing aluminium, most commonly Potassium Alum (KAl(SO₄)₂·12H₂O). |
| Alternative Names | Potassium Alum, Potash Alum, Phitkari (in Hindi) |
| Health Benefits | It acts as an astringent and is used in diarrhoea, dysentery, menorrhagia, etc. It prevents body odour, promotes wound healing, and has antibacterial properties. |
| Forms Available | Powder, Crystal, Block, Liquid |
| Recommended Dosage | Topical application is typically recommended for skin use. When used in water purification, 1-2 grams per litre of water is standard. Always follow product guidelines. |
| Precautions | It should not be ingested in large quantities. Avoid direct contact with open wounds. Pregnant or breastfeeding women should consult a doctor before use. |
| Side Effects | It can cause skin irritation or dryness. Ingesting large amounts can be toxic. |
| Interactions | No significant interactions are known, but excessive use should be avoided on sensitive skin. |
| Storage | Store in a cool, dry place away from moisture. Keep tightly sealed when not in use. |
In medical journals, alum is often referred to by several alternative names, including:
Alum is known by various local names in different languages and regions. For example:
Here’s the chemical composition of Alum in a tabular format:
| Component | Description |
| Potassium Sulphate (K₂SO₄) | It provides the potassium ion, essential for alum’s crystalline structure, and helps in coagulation processes. |
| Aluminium Sulphate (Al₂(SO₄)₃) | Supplies the aluminium ion, responsible for alum’s astringent and antibacterial properties and water purification. |
Alum Formula: KAl(SO₄)₂·12H₂O
This highlights the roles of potassium sulphate and aluminium sulphate in alum.
Alum, a natural mineral, is known for its numerous health benefits. It helps purify water, soothe minor cuts, and maintain oral health. Alum also minimises skin irritation, calms razor burn, and tightens pores. Here are some key health benefits of alum:
Alum may temporarily alleviate discomfort from mouth ulcers due to its astringent properties, but it is not a cure. Proper oral hygiene and consultation with a dentist are recommended for persistent mouth ulcers.
Alum may help soften hard skin and provide some relief for cracked heels when dissolved in warm water, but it is not a substitute for antifungal treatments. For athlete's foot, it’s essential to consult a healthcare provider for effective antifungal medications.
Alum has been applied as an aftershave treatment for years due to its antibacterial and astringent nature; it aids in the treatment of minor injuries such as cuts and stops bleeding while at the same time tightening the skin. Avoid using alum stones that are used in barber shops to prevent infections.
Alum is widely used to clarify water by coagulating the dispersed material within the water and making the water transparent. Adding alum powder to muddy water helps settle the impurities, leaving clean water on top.
Alum is well-known as a natural deodorant because of its antimicrobial features. Unlike chemical-based antiperspirants, it fights against the bacteria responsible for body odour while not clogging the sweat glands, making it healthier.
Alum benefits include its use for hair removal when mixed with rose water, effectively slowing down hair growth over time. Additionally, it has skin-tightening properties. It can help reduce wrinkles. It also works well in face packs for acne when combined with turmeric or Multani mitti.
An alum sitz bath may offer temporary relief for haemorrhoids by soothing the area, but it is not a substitute for medical treatment. Consult a healthcare provider for proper haemorrhoid care and treatment.
Alum is a versatile compound and is effective in the following ways:
Alum is an agent used in water treatment processes, especially in flocculation. It assists in the clotting of foreign particles that, in this case, it hampers the water flow to facilitate the removal of these particles, hence providing clean and safe water.
In skincare, alum is appreciated for the astringent effect which it produces. It helps in skin reformation, shrinks pores, and reduces acne scars for skin renewal. It also has antiseptic properties, which can be used to manage minor injuries such as cuts and scratches.
Alum is a popular ingredient in natural deodorants because it inhibits bacterial growth, which is responsible for body odour. It is most commonly used as a crystal and directly on the skin.
The following measures should be taken when using alum (aluminium sulphate) for medical purposes:
Alum, a chemical compound known as potassium aluminium sulphate, has several uses in health and hygienic aspects. Following are some recommended uses of alum:
Steps to use:
Steps to use:
Steps to use:
Steps to use:
Steps to use:
For any application, the recommended dosage of alum can differ. Here are some general guidelines:
Important Considerations:
Disclaimer
The recommended dosage information for alum provided here is for general guidance only and may vary depending on the specific application and individual circumstances. Always consult a qualified healthcare professional or relevant expert before using alum for any medicinal or therapeutic purposes. Avoid self-medication and discontinue use if any irritation or adverse reactions occur.
Alum, specifically potassium alum may be incompatible with some drugs; it may hence change the said drugs’ action or enhance the side effects of the drug. As with all treatments, alum should never be self-administered without seeking advice from a health care worker.
Recommendations: One should not assume that alum does not have side effects or possesses any potential for interaction with other drugs; therefore, anyone intending to use alum should do so under the prescription of a qualified doctor. Supervision and a possible dose of champagne may be required to prevent side effects.


























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