Is it bad for womens health to drink semen?

No. In general, this is a very safe activity after being in a monogamous relationship where both partners have been tested for sexually transmitted disease. I have seen a patient in the past who got diarrhea each time she swallowed her partner's semen. My theory is that she had an allergic reaction to some protein in her partner's semen.
No, as long as... No, as long as the semen comes from a man who is healthy and doesn't have any transmissible diseases.