Will Hair Lost to Chemotherapy Grow Back? (2026 Update)

In most cases, hair lost during chemotherapy starts growing back after treatment ends. According to National Cancer Center Korea, regrowth begins 6–12 months after treatment finishes.

Key Takeaways

• Hair loss appears 1–2 weeks after starting chemotherapy and peaks at 2 months. (National Cancer Center Korea)
• Regrowth begins 6–12 months after treatment ends. (National Cancer Center Korea)
• Targeted therapies may cause nail changes or loss of hair color instead of hair loss, and most of these effects resolve once treatment ends. (U.S. National Cancer Institute, NCI)
• With radiation therapy such as proton therapy, hair loss occurs only in areas where the head was irradiated — if the scalp isn't treated, hair is generally preserved.
• Besides hair loss, side effects such as nausea/vomiting, mouth sores, and low white blood cell counts can occur around the same time, so it helps to keep a record of symptoms.

Why Does Hair Loss Happen, and When Is It Worst?

• Anticancer drugs affect not only cancer cells but also normal cells that divide quickly, and hair follicle cells are among them.
• According to National Cancer Center Korea data, hair loss begins 1–2 weeks after chemotherapy and is most severe at 2 months.
• The exact timing can feel different from patient to patient, and it can also vary depending on the dose and administration schedule of the same drug.

When and How Does Hair Grow Back?

• National Cancer Center Korea explains that regrowth begins 6–12 months after treatment ends.
• In other words, hair doesn't start growing back immediately once treatment finishes — it takes some time before the regrowth phase begins.
• Since the speed and pattern of regrowth can vary by individual, it's best to discuss your specific timeline and condition with your medical team.

Does Hair Loss Pattern Differ by Treatment Type?

• Yes, it does. Cytotoxic chemotherapy drugs can cause whole-body hair loss, whereas the most common side effects of targeted therapies are diarrhea and liver function problems — with loss of hair color and nail changes reported more often than hair loss itself. (U.S. National Cancer Institute, NCI)
• Notes on targeted therapy also explain that "hair loss and severe nausea are relatively less common, but each drug has its own characteristic reactions," and that many side effects resolve once treatment ends.
• With proton therapy, a type of radiation therapy, hair loss occurs only in the area of the scalp that was irradiated — if the head isn't treated, hair is generally preserved.
• Immune checkpoint inhibitors commonly cause rash, diarrhea, and fatigue, and hair loss is not treated as a key side effect in these materials.

What Other Symptoms Can Accompany Hair Loss?

• Nausea and vomiting affect about 70–80% of chemotherapy patients, appearing within 1–8 hours after administration and potentially lasting up to a week. (National Cancer Center Korea)
• Mouth sores typically appear around 5–7 days after treatment and fully resolve after about 2–3 weeks. (National Cancer Center Korea)
• White blood cell counts start to drop about 1 week after treatment begins, reach their lowest point at 2 weeks, and recover by 3 weeks. (National Cancer Center Korea)
• During periods when these symptoms overlap, watch for chills or a fever of 38°C or higher, and contact your medical team right away if these occur.

FAQ — My treatment is completely finished, but my hair still hasn't grown back. Is that normal?

Since regrowth typically begins 6–12 months after treatment ends, if only a few months have passed since finishing treatment, you may simply be before the usual regrowth window. (National Cancer Center Korea) That said, individual differences exist and outcomes can vary by drug, dose, and overall health, so if there's still no change after that period, it's a good idea to discuss it with your medical team.

FAQ — Does targeted therapy or immunotherapy mean no hair loss at all?

The more accurate description is "different," not "none." Targeted therapies commonly report diarrhea, liver function problems, nail changes, and loss of hair color instead of hair loss, and many of these side effects can be managed and mostly resolve once treatment ends. (U.S. National Cancer Institute, NCI) Immune checkpoint inhibitors commonly cause rash, diarrhea, and fatigue, and require more attention to immune-related reactions like thyroid function changes rather than hair loss.

Sources and Notes

• This article was written based on materials covering principles of managing chemotherapy side effects, immunotherapy and targeted therapy side effects, and notes on targeted therapy, immunotherapy, and proton therapy (National Cancer Center Korea, U.S. National Cancer Institute (NCI), NCCN patient guidelines).
• This content is provided for general medical information purposes only, and actual diagnosis, treatment methods, and outcomes may vary depending on individual condition. Please consult your medical team to determine an accurate diagnosis and treatment plan.