Unfortunately, there is a lack of information regarding hair loss AFTER finishing tamoxifen, although several women anecdotally have reported similar experiences.

Tamoxifen has anti-estrogen effects in breast tissue but estrogen-like effects in other tissues. One possible explanation is that your body (in particular your hair) is readjusting itself to the different levels of hormones following the withdrawal of tamoxifen; a similar experience to the many women who report hair loss following childbirth. Estrogen has varying effects on hair growth - it reduces bodily hair but promotes the growth of hair on your scalp. Theoretically, tamoxifen could be having an estrogen effect (and promoting hair growth); which is noticed as hair loss once the tamoxifen is stopped. More research is needed in this area.

Hair loss during tamoxifen therapy is much more common. One study reported hair loss or hair thinning in almost 25% of women prescribed endocrine therapies such as tamoxifen. In these women, tamoxifen may be having an anti-estrogen effect on their hair, and hair is likely to regrow once the tamoxifen is stopped.