Foundayo and the Contraceptive Pill: What You Need to Know

If you take an oral contraceptive and you are starting Foundayo, you need a second method of contraception for a period after you start and after every dose increase. That is the short answer, and it is the one thing on this page that cannot wait until the end.

The reason is mechanical rather than hormonal. Foundayo slows how quickly your stomach empties, which is part of how it controls appetite. Anything swallowed alongside it can be absorbed differently, and a contraceptive pill is something swallowed.

Key things to know

• Foundayo is the brand name for orforglipron, licensed by the MHRA on 10 August 2026 for weight management in adults.
• It delays gastric emptying, so it has the potential to affect how other oral medicines are absorbed.
• The effect of Foundayo on the absorption of oral contraceptives has not been evaluated in a clinical trial. The advice exists because of the mechanism, not because a failure rate has been measured.
• The approved product information advises people using oral hormonal contraception to switch to a non-oral method, or add a barrier method, for 30 days after starting Foundayo and for 30 days after each dose increase.
• On 5 June 2025 the MHRA advised that women who could become pregnant should use effective contraception while taking medicines in this group, and in some cases for up to two months between stopping and trying to conceive.
• If you are planning a pregnancy, speak to your prescriber before stopping treatment. The current UK product information advises stopping orforglipron at least 3 weeks before a planned pregnancy.
• If you become pregnant while taking Foundayo, contact your prescriber promptly. The current product information advises discontinuing orforglipron during pregnancy.
• Foundayo should not be used during pregnancy or breastfeeding. If you are planning to become pregnant, speak to your prescriber because the medicine should be stopped at least 3 weeks before a planned pregnancy.
• Weight loss can improve ovulatory function in some people whose fertility has been affected by excess weight. This means pregnancy may become possible even if conception previously seemed unlikely.

Does Foundayo affect birth control pills?

It may, and the advice attached to the medicine assumes that it does.

Foundayo delays gastric emptying and therefore has the potential to affect the absorption of oral medicines taken at the same time. A contraceptive pill works only if the hormone in it reaches your bloodstream in the amount expected, every day. Anything that changes absorption introduces uncertainty into that, and contraception is an area where uncertainty is not acceptable.

So the guidance is precautionary and it is specific. If you use an oral hormonal contraceptive, either switch to a non-oral method or add a barrier method for 30 days after you start Foundayo, and again for 30 days after each dose increase.

Why a weight loss tablet can affect a contraceptive pill

What delayed gastric emptying does to other tablets

Gastric emptying is the rate at which your stomach passes its contents into the small intestine, which is where tablets are mainly absorbed. Foundayo slows that rate. That is not an unwanted quirk of the medicine, it is part of how it works, because a stomach that empties slowly keeps you feeling full for longer.

The consequence is that a tablet swallowed while that process is slowed may reach the absorption site later, and potentially at a different concentration, than it would have done otherwise. For many medicines that does not matter. For a contraceptive it might, because contraceptive cover depends on consistent daily levels rather than on a total amount arriving eventually.

What has been tested and what has not

This is the part worth being precise about, because precision here is rare.

The effect of Foundayo on the absorption of oral contraceptives has not been evaluated in a clinical trial. There is no study showing that it reduces contraceptive effectiveness, and there is no study showing that it does not. The advice to use a second method comes from the known mechanism and from a sensible approach to risk, not from a measured failure rate.

That matters for how you read it. Nobody is telling you your pill has stopped working. You are being told that its reliability has not been confirmed under these conditions, and that contraception is not a suitable place to find out by experience.

Does this apply to every type of pill?

The advice is written for oral hormonal contraception generally, which covers both the combined pill and the progestogen only pill.

There is a practical reason not to treat the progestogen only pill as the lower risk option here. The rules for missed or delayed doses differ between progestogen-only pills, so check the instructions for your specific product rather than assuming all pills have the same timing window. A medicine that alters when and how a tablet is absorbed sits awkwardly alongside a contraceptive that is already sensitive to timing. If you take a progestogen only pill, that is a point to raise specifically rather than assume it is covered.

If you are not sure which type you take, the name is on the packet and a pharmacist can tell you in a moment. It is worth knowing before you start rather than during a phone call about a missed dose.

The two windows that carry the advice

Two periods carry the advice: the first 30 days after you start Foundayo, and 30 days after each dose increase.

The dose increase is where people get caught. Somebody takes the advice seriously in month one, settles into treatment, and then does not connect a routine dose change months later with the same 30-day window. Put the date of every dose change in your phone with a reminder 30 days later, and treat each one as a fresh start rather than a continuation.

Non-oral contraception options

A non-oral method removes the absorption question entirely, which is why it is the simpler answer for many people on this treatment.

Methods that do not rely on a swallowed tablet include the contraceptive implant, the intrauterine device and the intrauterine system, the contraceptive injection, the patch and the vaginal ring. Barrier methods also do not depend on absorption.

Which of these suits you depends on your medical history, what you have used before, whether you want something reversible quickly, and how you feel about a method that lasts for years rather than weeks. That is a conversation for a contraception provider rather than something to decide from a table. What this page can tell you is that the choice is worth having before you start Foundayo rather than three weeks in.

Vomiting, diarrhoea and lost cover

This is the second route by which contraceptive cover is lost on Foundayo, and it has nothing to do with gastric emptying.

Digestive side effects are common with this medicine, particularly when treatment starts and after a dose increase. If you vomit shortly after taking a contraceptive pill, that dose may not have been absorbed. Severe or prolonged diarrhoea can have the same effect.

The general principle is straightforward. If you vomit soon after taking your contraceptive pill, the dose may not have been absorbed. Severe or prolonged diarrhoea can also affect absorption. Follow the missed-pill instructions for your specific contraceptive or ask a pharmacist for advice.

There is an awkward overlap here that is easy to miss. The weeks when vomiting is likeliest on Foundayo are the same weeks when the absorption advice already applies. During those windows, digestive side effects and the 30-day precaution stack on top of each other rather than cancelling out.

Foundayo and pregnancy

Foundayo should not be used during pregnancy. There are no adequate and well-controlled studies of orforglipron in pregnant women, and animal studies have shown reproductive toxicity. If pregnancy occurs, treatment should be discontinued and the patient should contact their healthcare professional.

If you become pregnant while taking Foundayo

Speak to a healthcare professional and stop the medicine as soon as possible. Do not wait for a scheduled review and do not finish the pack you have.

Contact your prescriber as well, so that your treatment record reflects what has happened. If you take other medicines, mention them at the same appointment, because the review will cover more than one thing.

Planning a pregnancy

If you are planning to conceive, speak to your prescriber before stopping Foundayo. The current UK product information advises discontinuing orforglipron at least 3 weeks before a planned pregnancy.

Breastfeeding

Foundayo is not recommended while breastfeeding. If you are breastfeeding or planning to, tell your prescriber at the consultation rather than after treatment has started.

Weight loss and fertility: the change nobody plans for

This is the part of the topic that surprises people, and it deserves its own section rather than a line in a list.

Excess weight can reduce fertility, in part by disrupting ovulation. Losing weight can reverse that. Some people who had assumed conception was unlikely find that their cycles become more regular and ovulation returns while they are on weight management treatment.

Two things follow from that, and they pull in opposite directions.

If you are hoping to conceive in future, this is encouraging news, and it is a reason to plan the transition off treatment properly with your prescriber rather than improvising.

If you are not hoping to conceive, it means the contraception question is more important than you may have assumed, not less. People whose fertility was low have often relied on that informally. Weight loss can remove that assumption without any announcement. If that describes you, the contraception conversation is not a formality.

What to raise at your consultation

Contraception should come up before the first tablet, not after a problem. Bring these points yourself rather than waiting to be asked.

1. What you currently use. Name the method and, if it is a pill, say which type.
2. Whether you are planning a pregnancy, and roughly when.
3. Whether you are breastfeeding or intend to.
4. What you will do during the 30-day windows, at the start and after every dose increase.
5. How you will handle vomiting or diarrhoea, including who you will ask.
6. Everything else you take, including anything bought without a prescription, since gastric emptying can affect the absorption of other oral medicines too.

Contraception, pregnancy plans and breastfeeding should be discussed as part of the treatment assessment, particularly because the product information contains specific pregnancy and oral-contraception precautions.Treatment suitability depends on an individual clinical assessment.

Medical Disclaimer

This article is general information about prescription only medicine and is not medical advice. It does not replace an assessment by a qualified healthcare professional who knows your medical history, and it should not be used in place of the instructions supplied with your own contraceptive or your own weight management treatment. Foundayo should only be used under the supervision of an appropriately qualified prescriber, and results vary between individuals.

Always read the patient information leaflet supplied with each of your medicines and follow the advice your prescriber gives you. Do not take Foundayo if you are pregnant, trying to conceive or breastfeeding, and if you become pregnant while taking it, speak to a healthcare professional and stop as soon as possible. Suspected side effects can be reported through the MHRA Yellow Card scheme.