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When people undergo chemotherapy for cancer, they may lose some or all of their hair. Seeing hair regrow after treatment can be a heartening sign, but how long does it take?

Chemotherapy destroys cancer cells, but it also kills healthy cells. That is why it has some severe side effects, including possible hair loss.

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

Learn more about why chemotherapy causes hair loss.

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Hair may not grow back until chemotherapy drugs have completely left the body.

Chemotherapy can affect both healthy and unhealthy cells, including cells in the hair follicles that support hair growth.

This is why the hair on a person's head, eyelashes, eyebrows, and elsewhere on the body often falls out during treatment.

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

Hair does not start to grow back immediately after the last chemotherapy treatment. This is because it takes time for chemotherapy drugs to completely leave the body and stop attacking healthy dividing cells.

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 a month or two of the last treatment.

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

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. So, the scalp is always shedding some hair.

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

  • 2–3 weeks: Light, fuzzy hair forms.
  • 1–2 months: Thicker hair begins growing.
  • 2–3 months: An inch of hair may have grown.
  • 6 months: Some 2–3 inches of hair may have grown, covering bald patches. People with very short hair may be able to wear a previous 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.

In a 2019 study in the journal PLOS One, of 1,470 people who underwent chemotherapy as part of their breast cancer treatment:

  • Around 13% of respondents said that their hair started growing back before treatment ended.
  • Around 80% of respondents said that it grew back after an average of 3.3 months after stopping treatment.
  • A small percentage said that it did not grow back or had not grown back 6 months after treatment ended.

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

Some hair follicles may enter the active growth period before others. When this happens, hair length can vary, which also makes it more difficult to style. Likewise, it may look patchy or unruly at first.

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

Some people talk about "chemo curls," which occur when the hair grows back curlier, more brittle, or more unruly than before. It may also grow back a different color.

Also, according to the PLOS One study paper:

  • Around 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 whiter or grayer.

Sometimes, the change is short lived. In other cases, it may be permanent. There is no way to predict whose hair will change texture after chemotherapy, or if the change will be permanent. That said, taking docetaxel or busulfan 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 the genes that control hair growth.

The following are some hair care tips that can help keep a person's hair healthy as it regrows:

Limit brushing and styling

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

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

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

Try hair regrowth treatment

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A person should talk to their doctor before using any hair regrowth treatments.

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

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

However, people should discuss the risks and benefits of hair regrowth treatments with their doctor before using them.

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

For production:

Also, a range of minoxidil products are available for purchase online.

Losing hair during 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 and may be cooler and more comfortable to wear.

The Food and Drug Administration (FDA) have approved a cold cap that may help prevent hair loss during chemotherapy for both men and women.

Known as the Digni-Cap, it works by cooling the scalp to reduce the likelihood of alopecia in people undergoing cancer treatment.

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

Should I have chemotherapy? Will it work? Find out more here.

Q:

Is it a good idea to use hair regrowth products?

A:

Over-the-counter (OTC) topical Rogaine 2% is a hair regrowth product that a person can try on the scalp.

Apply carefully, since the medication can sometimes cause hair growth in undesired locations. Avoid any other OTC hair regrowth products without first discussing it first with a physician.

It best to discuss any hair regrowth products with a doctor, as well as an oncologist, before use.

Owen Kramer, MD Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.