Vaginal spermicides must be inserted no more than minutes before intercourse.

60 minutes before sexual intercourse. There are different types of spermicides which come in different forms such as gel, foam, suppositories and films. All these forms have one thing in common, they contain a chemical referred to as nonoxynol-9, an active component that kills the sperms. The reason why spermicide must be applied 60 before intercourse to give it enough time to spread and dissolve. Again most of these spermicide are effective for only one hour and if they stays in vagina for more than one they become ineffective. it is also advisable that after sexual intercourse, another round of spermicide is applied. 

Dna overload will accrue