Washing the hair when doing ghusl (full ablution) after having intercourse is obligatory. This ruling does not differentiate between men and women.

The reasons for ghusl are: the emission of semen, contact between the genitals, menstruation and nifas (post-natal bleeding), and death. Ghusl is recommended on the two ‘Eids, after washing a dead body; before entering ihram or entering Makkah; and for a woman who is suffering from istihadah.

It is not permissible for a woman to have sex with her husband until she performs ghusl after her period.