Compare

External Condom vs Vaginal pH Modulator

A side-by-side comparison of two birth control methods — efficacy, cost, how they work, and who shouldn't use them.

Last verified October 11, 2026Updated October 12, 2026

Side-by-side comparison

External Condom A barrier method worn over the penis that also lowers the risk of STIs, available over the counter.
Vaginal pH Modulator A prescription gel used before sex that keeps vaginal pH acidic to disable sperm.

Method	External Condom A barrier method worn over the penis that also lowers the risk of STIs, available over the counter.	Vaginal pH Modulator A prescription gel used before sex that keeps vaginal pH acidic to disable sperm.
Efficacy	External Condom 87% typical use Least effective: under 90 out of 100 people successfully prevent pregnancy per year.	Vaginal pH Modulator 86.3% typical use, over 7 menstrual cycles Measured over 7 menstrual cycles, not over a year, so it cannot be compared directly with first-year rates.
Cost	External Condom $0–$2 per unit Insurance: Varies	Vaginal pH Modulator $0–$362 per package Insurance: Usually
Duration	External Condom Single use	Vaginal pH Modulator Single use (one dose up to 1 hour before each act of sex)
Reversibility	External Condom Reversible	Vaginal pH Modulator Reversible
STI protection	External Condom Yes	Vaginal pH Modulator No
How it works	External Condom A sheath worn over the penis that keeps sperm from entering a partner's body. Latex and plastic condoms also block contact with semen and vaginal fluids that can carry STIs.	Vaginal pH Modulator A gel containing lactic acid, citric acid, and potassium bitartrate keeps vaginal pH in the normal acidic range even in the presence of semen, which reduces sperm motility.
Prescription	External Condom Not required Over-the-Counter	Vaginal pH Modulator Required Telehealth Prescription
Side effects	External Condom Allergic reaction to latex in people with a latex allergy	Vaginal pH Modulator Vaginal burning or irritation Increased risk of urinary tract infection Rare allergic reaction
Who shouldn't use this	External Condom Known allergy to latex (use polyisoprene or polyurethane instead)	Vaginal pH Modulator Recurrent UTIs or urinary tract abnormalities (FDA label says avoid use) Hypersensitivity to lactic acid, citric acid, or potassium bitartrate (FDA label says avoid use)

Key differences

Vaginal pH Modulator's effectiveness was measured over 7 menstrual cycles, not over a year, so it is not compared with External Condom's. How long it lasts: External Condom, single use; Vaginal pH Modulator, single use (one dose up to 1 hour before each act of sex). STI protection: only with External Condom. A prescription is needed for Vaginal pH Modulator, not for External Condom. External Condom: costs $0–$2 per unit. Vaginal pH Modulator: costs $0–$362 per package.