Spermicide is a type of contraceptive that kills sperm or stops it from moving. You insert spermicide in the vagina before sex. The chemicals in the spermicide, such as nonoxynol-9, prevent sperm from entering the uterus. You can get spermicide over-the-counter. It's available in many forms, including cream, gel, foam, film, suppository and tablet.

Spermicide isn't a very effective birth control method when used alone. However, you can use spermicide with a barrier method — such as a condom, diaphragm or cervical cap — to improve its effectiveness with preventing pregnancy. Spermicide doesn't protect against sexually transmitted infections.

Newer to the market is a vaginal pH regulator gel (Phexxi) that immobilizes sperm, so they can't get to an egg to fertilize it. Similar to some types of spermicide, you put the gel in your vagina with a pre-filled applicator. This type of contraceptive gel is available by prescription only.

Spermicide is a contraceptive that helps prevent pregnancy. Spermicide:

• Is most effective when used with a barrier method, such as a condom, diaphragm, contraceptive sponge or cervical cap
• Doesn't require you to rely on your partner for birth control
• Doesn't require a prescription
• Doesn't have the same side effects as hormone-based birth control methods
• Increases lubrication during sex

Your health care provider may discourage use of spermicide if:

• You're at high risk of contracting HIV, or you have HIV or AIDS
• You have frequent urinary tract infections
• You're at high risk of pregnancy — you're younger than age 30 or you have sex three or more times a week
• You're not likely to consistently use spermicide along with other barrier methods

Vaginal pH regulator gel (Phexxi) also helps prevent pregnancy. It provides a nonhormonal option for birth control to be used right before you have sex.

About 28 out of 100 women who use spermicide alone will get pregnant in the first year of typical use. The vaginal pH regulator gel has shown similar results. Using backup birth control can reduce the risk of pregnancy.

Spermicide may increase the risk of urinary tract infections. Vaginal irritation — such as burning or itching or a rash — is the most common side effect of spermicide. Spermicide may also cause an allergic reaction. Spermicide may cause penile irritation or burning urination in your sexual partner.

Spermicide doesn't prevent sexually transmitted infections. Using spermicide frequently may increase vaginal irritation from the spermicide's active ingredient, nonoxynol-9, which may increase the risk of contracting HIV or other sexually transmitted infections (STIs). Rectal use of spermicide isn't recommended because it may increase the risk of getting an STI.

Vaginal pH regulator gel can cause vaginal itching or a burning sensation in the vagina. Penile irritation is also possible. More research is needed to know whether this contraceptive gel might protect against STIs.

You can use vaginal pH regulator gel in combination with most types of birth control, but it's not recommended for use with the vaginal ring.

Before using spermicide or a vaginal pH regulator gel, read the product instructions carefully. Consult your health care provider if you have any concerns.

To use spermicide:

• Choose a type of spermicide. Foams, gels and creams begin working immediately, while suppositories, films and tablets need to be inserted 10 to 30 minutes before sex to dissolve. If more than one hour passes between the application of spermicide and sex, reapply spermicide.

• Apply spermicide. Find a comfortable position, such as lying down. Using an applicator or your fingers, insert spermicide into your vagina on or near your cervix.

  If you use an applicator, fill the applicator with the recommended amount of cream, gel or foam and insert it into your vagina as far as it will go. Push the plunger on the applicator to release the spermicide near your cervix.

  To insert spermicide by hand, wash and dry your hands and place the suppository, film or tablet on your fingers. Slide your fingers along the back wall of your vagina as far as you can so that the spermicide covers or rests on or near your cervix.

  If you're using spermicide with a diaphragm or cervical cap, follow the instructions that come with the device. If you have sex more than once, apply fresh spermicide before each sexual encounter.

• Be cautious after sex. For maximum effectiveness, make sure the spermicide remains in your vagina for at least six hours after sex. After six hours, there's no need to clean any remaining spermicide from your vagina. Douching isn't recommended — but if you choose to douche after sex, wait at least six hours.

Similar to spermicide, you apply the vaginal pH regulator gel (Phexxi) directly to your vagina. The combination of lactic acid, citric acid and potassium bitartrate in the gel immobilizes sperm so that they can't fertilize an egg. You need to apply the gel within an hour before having sex and reapply the gel each time you have sex.

Talk with your health care provider if you develop persistent vaginal irritation or recurring urinary tract infections after using spermicide or a vaginal pH regulator gel.