Contraception Methods Explained: Effectiveness, Side Effects, and How to Choose

Understanding Effectiveness

When comparing contraceptive methods, it is important to understand two measures:

• Perfect use — Effectiveness when the method is used exactly as directed, every time.
• Typical use — Effectiveness accounting for real-world use, including occasional mistakes or inconsistency.

The gap between perfect and typical use varies by method. Methods that require less user action (like implants or IUDs) tend to have smaller gaps. The effectiveness figures in this article are drawn from the CDC list of contraceptive methods and typical-use failure rates and the NHS contraception guide.

Barrier Methods

External (Male) Condoms

• Typical use effectiveness: About 87%
• Perfect use: About 98%
• Key benefit: Only method that also protects against STIs
• Considerations: Must be used correctly every time; can break or slip if used incorrectly

Internal (Female) Condoms

• Typical use effectiveness: About 79%
• Perfect use: About 95%
• Key benefit: Can be inserted before sexual activity; provides STI protection
• Considerations: Less widely available; requires practice

Diaphragm

• Used with spermicide; must be fitted by a healthcare provider
• Does not protect against STIs

Hormonal Methods

Combined Oral Contraceptive Pill

• Typical use: About 93%
• Perfect use: Over 99%
• Contains oestrogen and progestogen
• Must be taken daily at roughly the same time
• Common side effects: Nausea, breast tenderness, mood changes, breakthrough bleeding (usually settle within a few months)
• Not suitable for everyone — your clinician will check your medical history

Progestogen-Only Pill (Mini-Pill)

• Typical use: About 93%
• Perfect use: Over 99%
• Must be taken at the same time daily (timing window varies by type)
• May be suitable for people who cannot take oestrogen

Injectable Contraception

• Given as an injection every 8–13 weeks depending on the type
• Typical use: About 96%
• Perfect use: Over 99%
• Common side effects: Irregular bleeding, weight changes, delayed return to fertility

Contraceptive Patch

• Applied to the skin weekly for three weeks, then one week off
• Similar effectiveness and side effects to the combined pill

Vaginal Ring

• Inserted for three weeks, removed for one week
• Releases hormones similar to the combined pill

Long-Acting Reversible Methods (LARCs)

Intrauterine Device (IUD) — Copper

• Effectiveness: Over 99%
• Hormone-free; works for up to 10 years
• May cause heavier or more painful periods initially
• Can also be used as emergency contraception if inserted within 5 days

Intrauterine System (IUS) — Hormonal

• Effectiveness: Over 99%
• Releases progestogen; works for 3–8 years depending on the type
• Often reduces period bleeding and pain
• Common brand names include Mirena and Kyleena

Implant

• Effectiveness: Over 99%
• Small rod inserted under the skin of the upper arm
• Works for up to 3 years
• Common side effects: Irregular bleeding patterns
• Quick return to fertility after removal

Emergency Contraception

Emergency contraception is not a regular method but an option after unprotected sex or contraceptive failure.

Emergency Contraceptive Pills

Timing below follows the WHO emergency contraception fact sheet and the NHS emergency contraception guide.

• Levonorgestrel (e.g., Plan B): Most effective within 72 hours, can work up to 120 hours
• Ulipristal acetate (e.g., ella): Effective up to 120 hours
• Not 100% effective — the sooner taken, the better

Copper IUD

• Most effective form of emergency contraception
• Can be inserted up to 5 days after unprotected sex
• Also provides ongoing contraception

Permanent Methods

Tubal Ligation (Female Sterilisation)

• Surgical procedure; considered permanent
• Over 99% effective

Vasectomy (Male Sterilisation)

• Surgical procedure; considered permanent
• Over 99% effective after confirmation
• Simpler procedure than tubal ligation

Both permanent methods should be considered irreversible. Counselling is important before proceeding.

Fertility Awareness Methods

These involve tracking your cycle to identify fertile days and avoiding unprotected sex during those times.

• Require consistent tracking (temperature, cervical mucus, calendar)
• Typical use: About 76–88% effective
• Perfect use: Can be over 95% for some methods
• Not suitable if your cycle is irregular
• Do not protect against STIs

How to Choose the Right Method

There is no single "best" method — the right choice depends on your:

• Health history — Some methods are not suitable for people with certain conditions
• Lifestyle — Daily pill-taking may not suit everyone
• Plans — If you want to conceive soon, a LARC might not be your first choice (though fertility returns quickly after removal)
• STI risk — If STI protection is important, condoms should be part of your plan
• Side effect tolerance — If you are concerned about hormonal side effects, copper IUD or barrier methods are hormone-free options
• Access — Not all methods are equally available everywhere

A healthcare provider can help you weigh these factors and find the best option for your situation.

When to Speak to a Clinician

Consult a healthcare provider if:

• You want to start or change your contraception
• You are experiencing side effects that concern you
• You have missed pills or your method may have failed
• You have medical conditions that might affect your contraception choices
• You are considering permanent sterilisation
• You need emergency contraception