How long does it take for fertility medications to take effect?

It does depend from person to person. It can take anything from 6 to 18 months for fertility medication to take effect.

For men especially it can take a while for the testes to “restart”. After long term HRT the testes may have shut down totally so it might take a few months for them to restart and be able to produce testosterone and sperm.

This is one reason why some doctors use hCG as a form of testosterone therapy, it keeps the testes primed and active and sperm production can be initiated quicker.

In a lot of cases natural conception is possible with fertility treatment.

If only a low level of sperm production is achieved it might be possible to harvest enough sperm or eggs to use in IVF or another form of assisted fertilisation technique.