As I understand it, radiation poisoning (acute radiation syndrome) is fatal because the radiation kills cells. However, why do victims experience hair loss at such an early stage in the process?

  • $\begingroup$ Any link at hair loss? I doubt it. Hair loss may be due to chemoterapy if the affected persons contracted cancer or leukemia. $\endgroup$
    – Anixx
    Commented Oct 5, 2015 at 13:18
  • $\begingroup$ Radiation levels used for treatment of cancer does kill nearly all hair in the target zone. $\endgroup$ Commented Mar 28, 2022 at 23:56

1 Answer 1


Radiation poisoning causes mutations in DNA that affect normal cell function, often causing them to die. Cells normally have a number of repair mechanisms but if the damage is too great they won't be able to do so. In particular, cells that are dividing quickly will not have time to repair their DNA before division and so die far quicker than other cells. Chemotherapy is built on this concept. By selectively introducing drugs or radiation that target fast-dividing cells, the cancer cells, which are very dividing rapidly and unchecked, are killed off before most normal cells.

However, there are some cells in the body that are very rapidly dividing. Hair cells are one such type, hence hair will often fall out during chemotherapy or radiation sickness. Another big cell type are those in the gut, which are constantly dividing. That's why you often see people in movies who have been exposed to radiation vomiting. The radiation targets those cells first, hence those are the first symptoms.

  • $\begingroup$ I suppose that in any radiation exposure, the skin is what is damaged first. So radiation burn on your scalp, may be the primary cause for acute hair loss. Possibly because of the lower penetration depth of α-radiation, which is more damaging. $\endgroup$
    – not2qubit
    Commented Feb 22, 2020 at 19:18

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .