Welcome to HCM,
Thanks for trusting Healthcaremagic and posting your query.
In my opinion there is no justification behind taking Zentel
tablets on 20th day of menstrual period.
For any infection and infestation these should be given prior to ovulation.
Azithral and Zentel comes under pregnancy
category (US FDA) B and C, thus should be avoided after conception.
Hope you found my response to your query informative and helpful.
If you have further concerns in this regard, you can submit those with Healthcaremagic as well.
With good wishes,