All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Ejaculation in this case may be permissible or prohibited depending on the circumstances; if the husband looked at his wife’s body and stared until he ejaculated; then it is permissible. However, if the man looked at a non-Mahram woman’s `Awrah or looked at the images of women who expose their bodies in the media until he was aroused and ejaculated, then such act is impermissible. Nonetheless, in both cases, Ghusl is obligatory.
As for the negative health effects that result from such act, normal ejaculation does not affect man’s health negatively, but excessive ejaculation affects man’s health. For further information on health effects, you may consult specialized doctors.
Allaah Knows best.