- Weight loss medications and bariatric surgery can reduce how well the oral contraceptive pill is absorbed
- This may mean the pill is not effective enough to prevent pregnancy
- Long-acting reversible contraceptives (LARCs) are a safer alternative — they don't rely on digestion
- Weight loss medications must be stopped well before attempting pregnancy
- After bariatric surgery, nutritional stability is needed before conception is safe
Important for women of reproductive age: If you are using weight loss medications or have had bariatric surgery, the oral contraceptive pill may not be absorbed reliably — and may not protect you from unintended pregnancy. Please discuss this with your doctor.
Why the Pill May Not Work During Weight Loss Treatment
Weight loss medications can slow gastric emptying and alter digestion, which affects how oral medications — including the contraceptive pill — are absorbed through the gut. Bariatric surgery goes further, physically reducing or bypassing sections of the gastrointestinal tract where absorption occurs.
In both cases, the result can be reduced absorption of the oral contraceptive pill, meaning it may not reach the blood at sufficient levels to reliably prevent pregnancy.
A Safer Alternative: Long-Acting Reversible Contraceptives
Long-Acting Reversible Contraceptives (LARCs) are a much more reliable option for women undergoing weight loss treatment, because they work independently of digestion entirely.
Relies on absorption through the gut. May be significantly reduced by weight loss medications or bariatric surgery.
Work systemically or locally — not through digestion. Reliable contraception regardless of weight loss treatment.
LARCs include the hormonal or copper intrauterine device (IUD) and the subcutaneous hormonal implant. Both are highly effective and unaffected by changes to digestion or gastrointestinal absorption.
Weight Loss Medications and Pregnancy
It is also important to know that weight loss medications are not safe to use during pregnancy. If you are planning to conceive, your doctor will advise you to wean off medication well in advance — the exact timing will depend on which medication you are taking.
After bariatric surgery, it is recommended to wait until your nutritional levels are replete and your weight loss has stabilised before attempting pregnancy. Losing weight during pregnancy is not recommended, as it can impact health outcomes for the baby.
When you're ready: Your doctor can guide you on the best time to transition from contraception to conception, ensuring a healthy pregnancy for you and your baby. Don't hesitate to raise this at your next appointment — it's an important conversation to have early.
If you have questions about contraception during weight loss treatment, or about planning a pregnancy after bariatric surgery or medication, get in touch or book an appointment with your MedSurg Weight Loss doctor.
Medical disclaimer: This article is for general informational purposes only and does not constitute medical advice. Contraceptive needs vary between individuals — please consult your doctor to discuss the most appropriate contraception for your circumstances during weight loss treatment.