Spermicides are composed of a spermicidal agent in a carrier that allows dispersion and retention of the agent in the vagina.
Nonoxinol-9 is the most commonly used spermicidal agent and is the active component in the only prescribable spermicide available in the UK. Spermicidal contraceptives are useful additional safeguards but have low contraceptive efficacy if used alone. They are suitable for use with female barrier methods such as the cap and diaphragm but are not advised with condoms.
Spermicides are available as:
- Aerosol foam
In the UK, however, the only currently prescribable form is Gygel® contraceptive gel.
It is advised that women using a diaphragm or cap for contraception should use the device with spermicide. More spermicide is needed if intercourse takes place more than three hours after original insertion of the contraceptive device.
Spermicides are not recommended as an addition to condom use, as they are neither necessary for contraceptive efficacy of condoms nor useful for infection protection. Indeed, it is advised that spermicides should be avoided in men and women who might be at high risk of infection, as multiple use of spermicide may cause irritation to the vagina and rectum, increasing the chance of infection.
Therefore, the use of diaphragms or caps in women with HIV or at high risk of HIV infection is not normally recommended, as in most cases the risks outweigh the benefits.
Because of poor trial quality, how well spermicides work in preventing pregnancy is unclear. However, it is known that gel with the smallest amount of nonoxinol-9 is less effective in preventing pregnancy than products containing more of the same ingredient. Overall efficacy is poor in comparison to other contraceptive options, with a Cochrane review showing pregnancy rates within six months in trials ranging from 14-22%. Trials had a high discontinuation rate, or participants were lost to follow-up; the conclusion was that interpretation of the results was limited.
Current guidelines advise that diaphragms and caps should be used with a spermicide, although they recognise that evidence is insufficient to conclude whether the addition of a spermicide improves efficacy.[3, 4]
Cochrane reviews have found the contraceptive diaphragm with spermicide to be more effective than use with a contraceptive sponge.
Mode of action
Diaphragms and caps are barrier methods of contraception and therefore prevent fertilisation. They cover the cervix, acting as a barrier blocking the cervix as well as providing a reservoir for spermicide. Spermicide should be reapplied if the cap or diaphragm has been in situ for longer than three hours. Spermicide works by:
- Altering the integrity of the sperm cell membrane.
- Altering the vaginal pH, causing a hostile environment for sperm.
The advantages of a spermicide include additional lubrication and possibly improved efficacy.
The disadvantages are:
- It must be inserted prior to intercourse and reapplied if intercourse takes place more than three hours later.
- Some may find it messy, or smelly, or that it has an unpleasant taste.
- It may cause irritation and subsequent increased risk of transmission of infections.
- Occasionally it may induce an allergic reaction.
Further reading and references
Grimes DA, Lopez LM, Raymond EG, et al; Spermicide used alone for contraception. Cochrane Database Syst Rev. 2013 Dec 512:CD005218. doi: 10.1002/14651858.CD005218.pub4.
British National Formulary (BNF); NICE Evidence Services (UK access only)
Barrier methods for contraception and STI prevention; Faculty of Sexual and Reproductive Healthcare (August 2012 - updated October 2015)
Cook L, Nanda K, Grimes D; Diaphragm versus diaphragm with spermicides for contraception Cochrane Database Syst Rev. 2003
Kuyoh MA, Toroitich-Ruto C, Grimes DA, et al; Sponge versus diaphragm for contraception: a Cochrane review. Contraception. 2003 Jan67(1):15-8.