Encyclopedia · drug with hair side effects
Chemotherapy hair changes ("chemo curls")
Hair often regrows curlier, softer or a different colour after chemotherapy, but nobody has measured how often; what is better documented is that permanent thin regrowth is more common than once believed.
What it is
Chemotherapy drugs kill fast-dividing cells, including growing hair follicles, so hair is usually lost within weeks. When treatment ends, hair regrows, often with a different texture or colour. This page is about the aftermath. Chemotherapy is prescription-only and given for serious disease; nothing here is a reason to change treatment.
How it works
A 2019 review lists pigment and texture changes among the therapy-related hair disorders and says the mechanisms are incompletely understood, so no prevention guidelines exist. Freites-Martinez 2019 Explanations such as follicle shape or pigment-cell disturbance during recovery are speculation; we found no controlled study that measured curl pattern before and after chemotherapy.
What the studies show
- Among 38 Black breast cancer survivors interviewed, regrowth was commonly described in texture terms (soft, "baby fine", loosely curled, wavy, straight). This is self-report, not measurement. Wilson 2022
- A 2026 scoping review reports severe alopecia in over 70% on anthracycline/taxane regimens, persistent alopecia up to 67% after doxorubicin-based regimens and nearly 50% after docetaxel combinations, higher than the older 1-15% estimate. Gaumond 2026
- Variants in the drug-pump gene ABCB1 were associated with persistent chemotherapy-induced alopecia (we read only the record). Nunez-Torres 2020
- A phase II trial of scalp cooling in 15 Black patients closed early for lack of efficacy: only 1 of 15 avoided significant hair loss. The authors suggest hair thickness, volume and cap design as factors. Dilawari 2021
How often texture or colour changes occur, and how long they last, has not been measured.
How it's used in studies
Not applicable; this is a side effect. Scalp cooling devices are the main prevention option studied.
Side effects and safety
Temporary total loss is expected; persistent patchy or thin regrowth occurs; brows and lashes may be affected. Treatment of persistent loss is unproven. Minoxidil is sometimes used with limited evidence.
Bottom line
Chemo curls are real in patient experience but unquantified. The solid findings are that persistent hair loss is more common than long believed and that scalp cooling may work less well on some hair types, based on a very small study. Discuss with a doctor.
Fun facts
- Patients often describe regrown hair as a different texture, yet the first rigorous attempts to quantify it are still missing.
- In a small trial, cooling caps largely failed in 14 of 15 Black patients, a reminder that hair type matters in supportive-care research. Dilawari 2021
Studies 5
Freites-Martinez A et al. Hair disorders in patients with cancer. J Am Acad Dermatol. 2019
Result: Chemotherapy, targeted drugs, immunotherapy and endocrine therapy can cause alopecia plus colour and texture changes; mechanisms unclear and no prevention guidelines.
Read the study ↗Wilson KB. 'And it'll come back real baby fine': Black women's experiences with hair loss and regrowth after chemotherapy. Qual Health Res. 2022
Result: Regrowth was commonly described in texture terms (soft, baby fine, loosely curled, wavy, straight); self-report, not measurement.
Read the study ↗Gaumond SI et al. Chemotherapy-induced alopecia in breast cancer patients. Cancers (Basel). 2026
Result: Severe alopecia in over 70% on anthracycline/taxane regimens; persistent alopecia up to 67% after doxorubicin-based and nearly 50% after docetaxel regimens.
Read the study ↗Nunez-Torres R et al. ABCB1 variants and persistent chemotherapy-induced alopecia. JAMA Dermatol. 2020
Result: ABCB1 gene variants were associated with persistent chemotherapy-induced alopecia (record only).
Read the study ↗Dilawari A et al. Does scalp cooling have the same efficacy in Black patients? Oncologist. 2021
Result: Closed early for lack of efficacy; only 1 of 15 avoided significant hair loss.
Read the study ↗Related
- Drug-induced hair changesMedicines can thin hair, regrow it curly, darken or whiten it, or lengthen lashes; this table sorts the best-known links by how strong the evidence is.
- MinoxidilThe most widely used hair-growth treatment, available as a cheap over-the-counter lotion or foam and as a prescription tablet, with a mechanism that is still only partly understood.
- TempolA free-radical scavenger painted on the scalp before radiotherapy kept hair in guinea pigs and, in a small phase I trial, protected the hair of some brain-radiotherapy patients, but it never became a product.
- Breast cancer endocrine therapy (tamoxifen, aromatase inhibitors)Anti-estrogen pills taken for years after breast cancer can cause female pattern-type thinning, and in one uncontrolled series topical minoxidil helped 80% of those assessed.
- Anagen effluvium (chemotherapy-induced hair loss)Abrupt loss of actively growing hairs because chemotherapy or radiation shuts down the dividing cells in the hair bulb; hair usually regrows, and scalp cooling is the main way to prevent part of the loss.