Why hair “gets used to” the products we use (Spoiler: It doesn’t!)

A widespread belief in hair care is that, over time, hair “gets used to” the cosmetic products we use, and as a result, their effectiveness fades. This theory is often used to explain why a product that initially impressed us seems to stop “working” as time goes by. Although this experience is common, the interpretation—based on the idea of adaptation—is not scientifically accurate.

Let’s deconstruct one of the most persistent myths in hair care and explain why the belief that hair “gets used to” products does not actually hold up.

Biological perspective of hair

From a scientific standpoint, hair does not have a mechanism of adaptation or “immunity” to cosmetic products. To debunk the myth, however, we need to understand what hair actually is. Hair is a dead, keratinized tissue. It is composed mainly of keratin and has no metabolism, nervous system, blood circulation, or ability to learn and adapt. Simply put: hair does not “learn”, does not “remember”, and does not “get used to” anything.

Why does a product seem to stop working?

The perception that a shampoo, mask, or leave-in conditioner “no longer works” is real. The cause, however, is not what we usually assume. The most common reasons include:

Product buildup: Many hair care products contain silicones, polymers, oils, proteins, and other ingredients. Over time, these substances can accumulate on the hair shaft, forming a film. The result? Hair looks weighed down, loses its volume and shine, and products seem not to work properly. In this case, what truly happens isn’t that hair has “gotten used to” the product. It’s the outer layer of the hair that has become coated.

Changes in hair needs: Hair needs do not remain constant over time. They are affected by factors such as climate and seasonal conditions, the frequency and intensity of heat styling tools, chemical treatments (coloring, bleaching), age, hormonal changes, and more. This explains why a product that was suitable during a specific period or circumstance may no longer deliver the same results—without necessarily having lost its effectiveness. As an example, a product that was ideal during winter may feel too heavy in summer. That does not mean it stopped working; it means that it no longer suits your current hair care needs.

Changes in the scalp: The scalp is a living tissue that undergoes changes in oiliness, sensitivity, composition, and microbiome balance. Since shampoos and cleansing products primarily target the scalp, any change in its condition may affect the perceived effectiveness of a product. For example, if we were using a shampoo designed to balance oil production, but our scalp has since “regulated” itself and now produces less sebum, the results will not be the same. Again, this is not a matter of hair “getting used to” the product, but rather a change in the scalp’s condition.

Psychological factors and expectations: Our brain plays a huge role in how we perceive effectiveness. When we first start using a new product, we pay closer attention to the results and observe improvements more carefully. Over time, however, the results become the new normal, the improvement is taken for granted, thus we are no longer impressed. This does not mean the product has stopped working, it simply means its effectiveness is no longer perceived as remarkable.

Is it necessary to frequently change products?

Changing products is not a priori necessary. However, it is advisable when hair needs change, the condition of the scalp shifts, or environmental factors differ.

The idea that hair “gets used to” products is a quite common yet oversimplified way of explaining more complex phenomena. Hair care should be based on evaluating actual needs, rather than on excessive product switching. The essential question is not whether a product should be changed, but whether it continues to meet the needs of your hair and scalp.

Discover MACROVITA hair care product line with red grape to find the products that best meet your personalized needs.