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Why Does Chemotherapy Cause Hair Loss

Chemotherapy is the use of medication to kill cancer cells. The chemicals used during chemotherapy work on cancer cells because these cells divide and grow quickly, and fast growing cells are targeted by the chemicals. However, the medication cannot distinguish between healthy cells and cancerous ones. Because chemotherapy targets rapidly growing cells, other healthy ones in the body that grow quickly can also be affected.

Effect of Chemotherapy Medications

Chemotherapy drugs may be broken down into various groupings based on their activity, attack and inhibition of cancerous cells.

Alkylating agents such as Temodar, Cytoxan, and chlorambucil damage cells and DNA directly and are used for most cancers including leukemia, sarcoma, lung, breast and ovary cancer.

Similarly, Antimetabolites such as 5-SU, Gemzar, and Xeloda inhibit and slow cellular growth. Antitumor antibiotics interfere with DNA and cellular replication and include Anthracyclines and non-anthracyclines such as Adiamycin and Mitomycin-D, respectively.

Mitotic Inhibitors are naturally-derived compounds – generally from botanical extracts – that stop/inhibit mitosis (cell division) in all phases of growth and include common medications such as Velban and Taxotere.

Other “quasi” chemotherapy cancer treatments include carticosteroids such as commonly prescribed prednisone and hormonal therapy – primarily for prostate or breast cancer – alter and inhibit normalized hair growth, cause hair loss or certainly slow growth. The effect of chemotherapy as it relates to hair loss is that in almost all prescribed treatments cells are killed or inhibited and follicles and hair are not safe - this is why chemotherapy causes hair loss. The good news is typically regrowth is resumed following treatment in many cases.

Growth Cycle

Hair follicles are responsible for growth. Hair grows in three cycles, and the entire life cycle for a hair lasts on average between three and five years. During the growth phase, it is actively growing, and the growing phase lasts a couple of years. Following the growth phase is a brief transitional phase that prepares the follicle for a period of rest. During the resting phase, the hair remains in the head, although it is no longer actively growing. The resting phase typically lasts several months, after which time it falls out and a new one begins to grow. Disruptions to the cycle of growth can cause partial to complete loss, and chemotherapy can disrupt the growth cycle.

Chemotherapy And Hair Loss

Depending on the type of cancer being treated, the medication used for chemotherapy differs. Most all of the types of medication used during chemotherapy will cause hair loss, although there are a few exceptions. In most cases, loss results from the aggressive attack of the medication on hair cells. Because the medication targets fast growing cells and cannot detect and specifically target cancerous cells, hair follicles are at risk because they are fast growing. When chemotherapy begins, hair follicles are aggressively attacked. In most types of chemotherapy, this results in the death of the hair cells growing. Hair that is growing falls out and the follicle will not begin to produce again until the chemotherapy treatment is complete.


In some cases, hair may become thin but total baldness may not result. This occurs because the growth cycle is disrupted, but the follicles aren’t destroyed. This means that while new hair will stop growing for the duration of the treatment, the hairs that are in the head resting will not necessarily fall out. The lack of new hair growth causes a thinning, but it does not result in total baldness. The use of a hair loss shampoo like Prominox and minimal styling may help the resting hairs remain in the head longer so that thinning does not accelerate.

Complete Loss

In many cases, chemotherapy results in total loss for the duration of the chemotherapy. After a couple of months post-treatment, the follicles will again begin producing, but it will take a while for growth to resume as normal. In addition, the hairs that are first produced from the traumatized follicles may be quite different from hair prior to chemotherapy. Many people experience a change in the texture or color due to the damage incurred by the follicles. After a few months, the damage is repaired and follicles will produce normally again.

Using vitamins for hair loss in women is one of the best ways to regrow hair in the best "environment" possible. While hair will regrow on its own following chemo, cellular damage has been done, immune system weakened, and nutrients and minerals have been depleted. Vitamin supplements can provide assurance your body is receiving the required nutrients for healthy growth. It is not uncommon for hair to regrow differently. Straight changes to curly, dark changes to light, gray hair goes away (temporarily), thin becomes thick. In any scenario, your best chances of healthy, fast regrowth is supplementing your diet following hair loss from chemotherapy.