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Chemotherapy destroys cancer cells, but it also kills healthy cells. As a result, it has some severe side effects, including possible hair loss.

Many people lose some or all of their hair if they undergo chemotherapy. However, this effect is rarely permanent, and the hair should grow back once treatment is over.

This article explains how long it takes for the hair to grow back and what to expect when it does.

A woman gets her hair cut after receiving chemo.Share on Pinterest
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Chemotherapy can affect not only cancerous cells but also healthy cells, including those in the hair follicles that support hair growth.

Damage to these cells can cause the head hair, eyelashes, eyebrows, and hair elsewhere on the body to fall out during treatment.

When hair loss occurs, it usually starts within 1–3 weeks of treatment and becomes more severe after 1–2 months.

After the last treatment, it takes time for chemotherapy drugs to leave the body altogether and stop attacking healthy dividing cells. Therefore, the hair does not start to grow back immediately.

Most people undergoing chemotherapy will begin seeing some thin, fuzzy hair a few weeks after their last treatment. Real hair may start to grow properly within 4–6 weeks.

However, some people who undergo chemotherapy experience permanent hair loss, research shows. Certain drugs, such as docetaxel (Taxotere), can have this effect.

Learn more about why chemotherapy causes hair loss.

Knowing about hair growth can help a person better understand hair regrowth after chemotherapy.

All hair goes through periods of rest, during which it does not grow. Hair can also fall out when it reaches a certain length or when a person pulls it. Due to this, the scalp is always shedding some hair.

The following timeline indicates what most people can expect to happen after chemotherapy:

  • 3–4 weeks: Light, fuzzy hair forms.
  • 4–6 weeks: Thicker hair begins growing.
  • 2–3 months: An inch of hair may have grown.
  • 3–6 months: Some 2–3 inches of hair may have grown, covering bald patches. People who previously had very short hair may be able to return to their original style.
  • 12 months: The hair may have grown 4–6 inches and be long enough to brush or style.

It can take several years for hair to return to its previous style, particularly for people who once had very long hair.

A 2019 study in the journal PLOS ONE involved 1,470 people who underwent chemotherapy as part of their breast cancer treatment. A survey of the participants revealed that:

  • On average, the hair started growing back 3.3 months after stopping treatment.
  • The hair started regrowing before treatment ended in about 13% of people.
  • In less than 0.5% of cases, the hair had not started to grow back 6 months after the end of treatment.

The Food and Drug Administration (FDA) has approved the DigniCap Cooling System, a cooling cap that may help prevent hair loss during chemotherapy.

It works by cooling the scalp to reduce the likelihood of alopecia in people undergoing cancer treatment.

After chemotherapy, the hair initially grows as thin fuzz. It may stick straight up or be difficult to style. Very fine hair may also not be visible from a distance.

Some hair follicles may enter the active growth period before others. When this happens, the length of hairs can vary, which may make the hair look patchy overall. It will likely also be more difficult to style.

Over time, the hair should settle into a more regular growth pattern. However, its texture might be different than it was before the treatment.

Some people talk about “chemo curls,” which occur when the hair grows back curlier, more brittle, or less manageable than before. In some cases, the hair may also grow back a different color.

The PLOS ONE study paper mentions that:

  • About 58% of respondents said that their hair grew back thinner, while 32% said that theirs did not change.
  • In 63% of respondents, the hair grew wavier or curlier, while 25% said that their hair texture did not change.
  • Hair color did not change in 53% of respondents, while 38% said that their hair grew back more white or gray.

Sometimes, the change is short-lived, but in other cases, it may be permanent. There is no way to predict whose hair will change texture after chemotherapy or whether the change will be permanent. However, taking Taxotere or busulfan (Myleran) may increase the chance of hair loss being permanent.

Doctors still do not fully understand why hair texture sometimes changes after chemotherapy. It could be that the treatment damages hair follicles or affects the genes that control hair growth.

People can take certain steps to keep their hair healthy as it regrows:

Limit brushing and styling

To avoid additional hair loss during the regrowth period, people should avoid:

  • brushing or pulling the hair excessively
  • styling the hair with heating devices, such as flat irons or blow-dryers
  • using dyes and perms for the first few months

Wearing a hat and applying sunscreen regularly can protect the scalp from UV rays while the hair is growing back.

Try hair regrowth treatment

Some drugs encourage hair regrowth after chemotherapy, but the results vary. Most hair regrowth drugs aim to treat hair loss resulting from causes other than chemotherapy.

Some research has suggested that minoxidil (Rogaine) might speed up hair regrowth or reduce hair loss during chemotherapy.

Doctors may, for example, recommend Rogaine for people who have had tamoxifen therapy for breast cancer. However, it can be messy and expensive. Pharmacies usually offer other forms of minoxidil that are cheaper.

A person should discuss the risks and benefits of hair regrowth treatments with their doctor before using them.

A range of minoxidil products is available for purchase online.

Losing hair while receiving chemotherapy can be upsetting, but the loss is usually only temporary.

Finding a suitable wig or hairpiece can help as an individual waits for their hair to regrow. Turbans and other types of headgear are also available that may be cooler and more comfortable to wear.

Hair regrowth after chemotherapy can be a positive sign of a person’s improving health.