Yes the current guidance is that testosterone should only be prescribed if a woman has adequate levels of oestrogen on HRT.

This is partly because replacing oestrogen to good levels often improves many of the symptoms (including libido) that may also have been attributable to low testosterone.

Whilst it has not been shown to be dangerous to use testosterone without being on oestrogen, the side effects mentioned above are more likely to occur if testosterone if used alone in peri-menopausal and menopausal women.