Most people who take the birth control pill have few or no problems, and the common side effects — nausea, headaches, breast tenderness, mood changes, and spotting between periods — are usually mild and tend to settle within the first 2–3 months. Serious side effects are rare but worth knowing, especially with estrogen-containing (combined) pills.
Common side effects
According to the NHS and Mayo Clinic, the more common side effects, especially in the first few months, include:
- Nausea (often eased by taking the pill with food or at night)
- Headaches
- Breast tenderness
- Mood changes
- Spotting or breakthrough bleeding between periods
- Changes to your periods — often lighter and more regular over time
These typically improve as your body adjusts. Pills differ in their hormone type and dose, so if one doesn't suit you, another may.
How long do they last?
Most mild side effects ease within two to three months. If a side effect is severe, or it's still bothering you after that adjustment period, talk to a provider — switching formulation frequently resolves it. There's no benefit to suffering through a pill that doesn't agree with you.
Serious side effects to watch for
Serious side effects are uncommon, but combined pills (which contain estrogen) carry a small increased risk of blood clots. ACOG notes this risk is low for most healthy people and is higher for those who smoke, are over 35, or have certain medical histories.
Tell your provider before starting the pill if you smoke, have had blood clots, migraines with aura, very high blood pressure, or certain other conditions — these can make estrogen-containing pills unsuitable. The progestogen-only pill may be an option instead.
What the pill doesn't do
- It doesn't cause long-term infertility. Fertility returns soon after stopping — see getting pregnant after stopping birth control.
- Weight gain is not a proven effect of the combined pill for most people — we cover the evidence in does birth control cause weight gain.
- It doesn't protect against STIs — use condoms for that.
Getting the balance right
Side effects are only half the picture. The pill is highly effective when taken consistently (see how effective the pill is) and has benefits beyond contraception for some people, such as lighter, more predictable periods. The goal is finding the method whose benefits and side-effect profile fit you.
The bottom line
Expect possibly a few mild, temporary side effects in the first couple of months. If they linger or trouble you, a different pill usually helps. Learn the warning signs of the rare serious risks, share your full health history with your provider, and choose the option that fits your life.
