What are spermicides and how do they work?

Spermicides contain the sperm-killing chemical nonoxynol-9 and work by setting up a chemical block at the entrance to the uterus. Here, sperm are trapped by the foam or gel barrier and destroyed by the chemical. The amount of nonoxynol-9 varies depending on the type and brand of spermicide.

What types of spermicides are available?


How effective are they?

  • Vaginal spermicides used alone are about 78% effective.
  • When spermicides are consistently used together with a condom, the combined effectiveness is 95% or greater—about the effectiveness of birth control pills.


  • Are non-hormonal
  • Available in several forms for personal convenience


  • May cause irritation to the vagina or penis or contribute to yeast and urinary tract infections
  • May be difficult or inconvenient to use because it must be applied immediately before intercourse
  • Possibly affects spontaneity
  • Effective for a limited time unless re-applied
  • Provides no protection against sexually transmitted infections
  • Need to be comfortable touching your vagina


  • Women may want to lie on their backs briefly after intercourse to be sure the foam, gel or film stays against the cervix to destroy sperm trying to enter.
  • Remember to re-insert another applicator of foam or gel or a new film for each act of intercourse.
  • There is no need to douche after using a spermicide, or at any other time unless recommended by your physician. If you want to douche, wait at least 8 hours after the last act of intercourse to allow the foam to destroy as many sperm as possible.
  • Keep an extra application of spermicide handy in case you need to use it.
  • Some people can have an allergic reaction to a spermicide. If an irritation develops, try changing brands.
  • Not recommended for frequent use in women who are at high risk of contracting HIV, as nonoxynol-9 may increase the risk of infection.
  • Condoms lubricated with nonoxynol-9 offer no more protection against pregnancy than those lubricated with silicone lubricants. To be effective, a spermicide must be used in a separate form as discussed above.

Talk openly with your partner and work together to be safe.
Contraception protects both of you.

Health Canada has issued the following recommendations regarding the use of nonoxynol-9 (N-9)

  • The benefits of any N-9 lubricated condom probably outweigh the risk of using no condom at all. However, the best STI and HIV barrier is a latex condom without N-9.
  • Condoms lubricated with N-9 should not be used for anal penetration
  • Those using N-9 lubricated condoms should be provided with information about the potential for irritation of the vaginal and cervical mucosa, which may in turn increase the risk of HIV
  • The adverse effects of using N-9 may not apply to women who use N-9 less frequently and therefore the risks and benefits of using N-9 should be evaluation on an individual basis.