A myth about washing your hair with cold water to make it shinier and grow faster has been floating around for what feels like eons. It's appealing to those lusting after longer hair, but is it actually true? We got to the bottom of the cold water case when we went to Caroline Ruggiero—trichologist and COO at Truly You Hair and Scalp Clinic in Ontario, Canada—with our questions. A trichologist is a specialist trained in the diagnosis and treatment of hair and scalp problems like hair breakage, hair loss and an oily scalp. Keep reading to find out what impact cold water has on your hair and scalp.
There are no known benefits of washing the hair and scalp with cold water
Growing hair is a matter of addressing internal and external factors. Internal factors refer to diet, nutrition, and lifestyle. Hair is the fastest growing tissue on the body and can be seen as somewhat of a barometer of what is going on within the body. A genetic predisposition cannot be changed, but epigenetic factors are important to consider. It is also important to understand that while there are deficiencies that exist within the body, topicals and certainly water temperature will have limited or no influence on the rate at which your hair grows. There is a wide range of various topicals available for the treatment of hair loss. Part of most treatments is a clarifying shampoo. The bottom line is that a clarifying shampoo will not rinse and clean the hair and scalp properly when used with cold water. Think about washing your hands. Warmer water molecules attract and lift dirt better. More importantly, your hands do not have sebaceous glands whereas the glands on the scalp produce oil and sebum. If you had oil on your hands, would you use cold water to remove it even with the best soap? I think not.
Temperatures have to be quite high to impose damage to the cuticle. I would guess above 350. At this level, we recommend a heat protecting spray for the hair. Water temperature will not get that high, so I don’t see this as a legitimate concern. Warm water is best. Right in the middle. Remember—healthy hair grows from a healthy scalp. Scalp being the soil that grows your crop (hair), needs to be cleansed and nourished. As I mentioned earlier, your scalp's sebaceous glands make this skin unique. We produce a waxy ester that is anti-microbial (sebum)—it is imperative that this bi-product be removed from the scalp, follicle funnel and hair. The more oily the scalp, the more often it needs to be washed. Another analogy is to think of your scalp as an extension of your face. If you were oily, would you wash your face with cold water? Unlikely. A cleanser designed to remove impurities but keep the skin balanced is best, and with warm water of course. The scalp is the same.
The bottom line
There's no scientific evidence to suggest that cold water makes your hair grow faster. Keep the scalp healthy, manage any internal issues, avoid over styling (high heat damage), and chemically process only with professional supervision and your hair will be in optimal health.