About 28 out of 100 women who use spermicide alone will get pregnant in the first year of typical use. 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 doesn't prevent sexually transmitted infections. Using spermicide frequently may increase vaginal irritation, which may increase the risk of contracting HIV or other sexually transmitted infections. You shouldn't use spermicide rectally because it may cause irritation and increase the risk of contracting sexually transmitted infections.

Spermicide may cause penile irritation or burning urination in your sexual partner.