Contraceptive effectiveness and safety of five nonoxynol-9 spermicides: a randomized trial

Obstet Gynecol. 2004 Mar;103(3):430-9. doi: 10.1097/01.AOG.0000113620.18395.0b.


Objectives: To estimate and compare the effectiveness and safety of 5 spermicides over 6 and 7 months of use, respectively. The spermicides included 3 gels containing 52.5 mg, 100 mg, and 150 mg of nonoxynol-9 per dose and a film and a suppository, each containing 100 mg of nonoxynol-9 per dose.

Methods: Women wishing to use only spermicide for contraception for 7 months were randomly assigned to use 1 of the 5 spermicides with emergency contraception backup. Participants were followed up for up to 30 weeks after admission.

Results: Of 1,536 women enrolled, 868 (57%) either relied on the spermicide for 6 months or became pregnant. The probability of pregnancy during 6 months of typical use of the spermicide was 22% (95% confidence limits 16%, 28%) in the 52.5-mg gel group, 16% (10%, 21%) in the 100-mg gel group, 14% (9%, 19%) in the 150-mg gel group, 12% (7%, 17%) in the film group, and 10% (6%, 15%) in the suppository group. The pregnancy risk in the 52.5-mg gel group was significantly different (P <.05) from that in either of the other gel groups. The pregnancy risks in the three 100-mg product groups were not significantly different (P =.35). No significant differences among groups were found in the 7-month probability of specified urogenital conditions.

Conclusion: The gel with the lowest amount of nonoxynol-9 was less effective than the 2 higher-dose gels. Among 3 products containing 100 mg of nonoxynol-9, formulation did not significantly affect pregnancy risk. All products were safe.

Level of evidence: I

Publication types

  • Clinical Trial
  • Comparative Study
  • Multicenter Study
  • Randomized Controlled Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adolescent
  • Adult
  • Dosage Forms
  • Dose-Response Relationship, Drug
  • Female
  • Genital Diseases, Female / chemically induced
  • Humans
  • Nonoxynol / administration & dosage*
  • Nonoxynol / adverse effects
  • Pregnancy
  • Probability
  • Spermatocidal Agents / administration & dosage*
  • Spermatocidal Agents / adverse effects
  • Suppositories
  • Treatment Outcome
  • Vaginal Creams, Foams, and Jellies


  • Dosage Forms
  • Spermatocidal Agents
  • Suppositories
  • Vaginal Creams, Foams, and Jellies
  • Nonoxynol