Soap for Hair

Woman holding a soap bar in her hands
Photo: Dreamstime
Q: I would like to save some money. Can I use soap (normally used for skin) to wash my hair?
 
A: You can, but standard body and hand soaps are usually a bad idea for your hair because they clean differently and have a very different chemical balance.
 
One of the main differences is the pH level. True soap is alkaline (often around pH 9–10), but the surface of your scalp is slightly acidic, usually around pH 5.5. Using a highly alkaline (high-pH) soap can increase friction between hair fibers and affect the cuticle (the protective outer layer of each hair strand) and leave your hair rougher, more tangled, frizzy, and more prone to breakage.
 
On top of that, bar soap can react with the minerals in hard tap water and create a sticky film known as soap scum. This can make your hair feel coated, sticky, and/or difficult to rinse clean. The harder your water, the more noticeable this effect can be.
 
Liquid hand soaps vary widely in how they are formulated. Some contain strong cleansing surfactants and can be drying or irritating after repeated use on the scalp, while others are milder. So it's not necessarily the fact that they're "hand soaps" that makes them harsh; it's the cleansing ingredients.
 
Even moisturizing body washes often contain heavy oils and conditioners designed purely for skin. These can leave some hair types limp and greasy, although this depends heavily on the product and your hair type.
 

Better Budget-Friendly Alternatives

The good news is that some manufacturers understand the desire for a simple, budget-friendly product and have created "hair + body" shower gels. These are dual-purpose cleansing products specifically formulated to work on both hair and skin, rather than ordinary body washes. They balance effective cleansing with scalp safety, offering a great low-maintenance, budget-friendly option.
 
If you are set on using a solid cleanser to save cash, look specifically for a shampoo bar that is formulated for hair. You may also come across syndet bars (synthetic detergent bars). These are synthetic detergent bars that do not react with hard water to form soap scum. However, a syndet bar isn't automatically suitable for hair or automatically pH-balanced for it. So, make sure to check that the particular product is intended for hair if that's how you plan to use it.
 
While swapping products can save cash, make sure you choose a product formulated with your hair and scalp in mind. A dedicated shampoo, shampoo bar, or a multi-use hair-and-body cleanser will be a more predictable choice for hair washing than traditional bar soap.
 
©Hairfinder.com
 
See also:
 
How does shampoo work?
 
How to save money on your hair care
 
Does expensive shampoo make a difference?