The most effective strength spermicide contains at least 100 mg of nonoxynol-9 per dose. You are more likely to get pregnant if you use a weaker spermicide. There is no difference in effectiveness between various spermicide types, such as gel, film, or suppository.

How can you make spermicide more effective?

How can I make spermicide more effective? Using spermicide correctly every single time you have vaginal sex is the way to go. The best way to increase your pregnancy prevention powers is to use spermicide along with another birth control method.

How effective are spermicidal agents?

Spermicides used alone are 75% to 85% effective in preventing pregnancy, but may be used with another barrier method, such as condoms or diaphragms. The effectiveness of spermicide increases with increasing age of the user, and is similar to that of the diaphragm in all age and income groups.