How is scalp cooling supposed to prevent hair loss?

The cooling causes the blood vessels in the scalp to become narrower. As a result, less blood reaches the cells in the roots of the hair. The cold also slows down the metabolism of the hair root cells somewhat. It is thought that this causes less of the chemotherapy medication to enter the hair root cells, so they are less damaged.

How well does scalp cooling work?

There are only few good-quality studies on scalp cooling. Overall, they show that people who did have scalp cooling treatment during their chemotherapy lost less hair than those who didn't have this treatment. They were less likely to need a wig after chemotherapy, for example.

These results aren't very conclusive though: Very few people took part in the studies, and there were usually many more women than men. Different cancer medications were used, and the duration of the chemotherapy varied. Various types of cooling caps were used too, and the extent of hair loss was measured in very different ways across the studies.

What are the possible disadvantages?

In general, scalp cooling is well tolerated and low-risk. Although it causes less of the chemotherapy medication to reach the scalp, there's no evidence that the cooling reduces the effectiveness of the chemotherapy.

The most common side effect is a headache. But some people find the cold to be so unpleasant that they stop the cooling.

Cooling caps are only suitable for preventing the loss of hair on the scalp. For some people, though, the loss of eyelash hair or eyebrow hair is particularly upsetting. For men, the loss of facial or body hair can be more of a problem than the loss of hair on the scalp.

Pressure on the scalp (scalp compression)

Some people try to prevent hair loss by exerting pressure on the scalp. This involves the use of tourniquets or tight caps. They cause less blood to reach the scalp, which is meant to reduce the amount of cancer medication that enters the hair roots. But there’s no proof that this method works. In studies, it only helped to prevent hair loss when it was used in combination with scalp cooling.

Medication

There is currently no medication that can prevent chemotherapy-related hair loss. Some people try out hair-growth products that are applied to the scalp, like those containing the drug minoxidil. But this drug wasn’t found to prevent hair loss in studies. It also isn’t clear whether hair grows back faster after the treatment if hair-growth products are used during chemotherapy. The possible side effects of minoxidil include an irregular heartbeat and swelling due to water retention in the tissue. If you take medication to reduce your blood pressure, minoxidil might increase the effect of that medication, causing dizziness or fainting.

Diet

Some vitamins and foods such as millet are considered to boost hair growth and are available as dietary supplements. But there's no proof that they can prevent chemotherapy-related hair loss or other forms of hair loss.