How Foundayo and anti-seizure medicines affect each other
Foundayo is a tablet taken once a day that mimics the effects of GLP-1, one of the hormones involved in appetite. It reduces hunger and food noise, which can make it easier to change eating habits.1
Some anti-seizure medicines can reduce the amount of Foundayo in the bloodstream. Foundayo also slows how quickly the stomach empties, which may change how quickly other tablets are absorbed.
Orforglipron is partly broken down by a liver enzyme called CYP3A4. Some anti-seizure medicines increase this enzyme’s activity and sharply reduce the amount of orforglipron in the bloodstream.1
In a drug-interaction study, carbamazepine reduced the total amount of orforglipron in the bloodstream over time by 82% and its highest blood concentration by 55%.
The UK prescribing information therefore advises avoiding carbamazepine, phenytoin, and other medicines that strongly increase CYP3A4 activity while taking Foundayo.1
Foundayo can change how quickly another oral medicine reaches the bloodstream because it delays stomach emptying.
The calculations submitted for the UK licence didn’t predict an effect large enough to change how commonly used medicines work, but they didn’t cover every anti-seizure medicine.1
If you vomit after taking an anti-seizure tablet, you may not absorb the full dose. Don’t repeat the dose or skip the next one unless your epilepsy team tells you to.
Research on other GLP-1 medicines is reassuring, but it doesn’t show that Foundayo improves seizure control.
A 2026 health-record study compared 8,688 adults with epilepsy and type 2 diabetes who started a GLP-1 medicine with 8,688 similar adults who started another blood-sugar-lowering medicine. Seizure recurrence was 18% lower in relative terms, equal to an absolute difference of 2.1 percentage points.2
The study used health records rather than random assignment and didn’t include orforglipron.
Some comparison treatments included insulin and sulfonylureas, a group of diabetes medicines that can cause hypoglycaemia. Severe hypoglycaemia can provoke seizures.2,7 This means some of the difference may reflect the comparison treatments rather than a direct protective effect from GLP-1 medicines.2,7
A second 2026 study followed 610 adults with epilepsy, obesity and type 2 diabetes. Starting a GLP-1 medicine wasn’t linked to more seizure-related hospital admissions or the need for an additional anti-seizure medicine.3
The GLP-1 group lost an adjusted average of 5.73% of their body weight over 12 months. Weight loss was also seen among people taking anti-seizure medicines associated with weight gain.3
This study also used health records rather than random assignment. The results included both lower and higher risks of seizure-related outcomes, so it found no clear difference rather than proving GLP-1 medicines have no effect.
Neither of these studies tested orforglipron directly. The best current evidence doesn’t suggest that GLP-1 medicines worsen seizure control, but Foundayo should be prescribed for weight management, not as an epilepsy treatment.
Which epilepsy medicines interact with Foundayo?
Carbamazepine and phenytoin should be avoided with Foundayo. Other anti-seizure medicines need an individual review because the combinations haven’t been studied directly.
| Medicine |
What the evidence says |
What to do |
| Carbamazepine |
Reduced the total amount of orforglipron in the bloodstream over time by 82% in an interaction study. |
The Foundayo prescribing information in the UK advises avoiding the combination. Don’t change carbamazepine without your neurologist. |
| Phenytoin |
Listed as a strong CYP3A4 inducer that may reduce Foundayo’s effectiveness. |
Avoid the combination unless a specialist provides a different plan. |
| Lamotrigine, levetiracetam, or valproate |
No direct interaction is listed in the Foundayo licence, but these combinations haven’t been studied specifically. |
Ask your prescriber and epilepsy team to review the combination. Continue the anti-seizure medicine exactly as prescribed. |
| Other anti-seizure medicines |
The effect on Foundayo depends on whether the medicine affects CYP3A4 and on how closely its blood level needs controlling. |
Have a pharmacist or neurologist check the exact medicine and dose before starting Foundayo. |
St John’s wort also strongly increases CYP3A4 activity and should be avoided with Foundayo. Tell your prescriber about prescription medicines, herbal remedies, and supplements.1
Medication review and seizure monitoring before Foundayo
Ask your Foundayo prescriber to send the proposed treatment plan to the clinician who manages your epilepsy. The review should happen before you take your first dose of Foundayo.
Record your usual seizure pattern for a few weeks before starting. Keep using the same diary during dose increases, noting seizures, sleep, missed medicines, vomiting, and alcohol intake.
Foundayo doses usually increase in stages. Nausea, vomiting and diarrhoea are more common while the dose is being increased and usually become less frequent later in treatment as the body becomes more adjusted to the medication.1
Foundayo has a low risk of causing hypoglycaemia when used without insulin or a sulfonylurea. The risk increases when either is used with Foundayo, and severe hypoglycaemia can provoke a seizure.1,7
If you use insulin or a sulfonylurea, agree on a blood-sugar monitoring plan before starting Foundayo. The prescriber may reduce the dose of that medicine to lower the risk.1
Our guide to Foundayo side effects gives the trial rates by dose and explains when symptoms need medical advice.
Agree on what to do if you vomit after an anti-seizure dose. Your epilepsy team needs to base the advice on the medicine, formulation, and how soon you became sick after taking your dose.
Don’t change the timing of an epilepsy medicine to separate it from Foundayo unless a pharmacist advises this. You can take Foundayo with or without food at any time of day, so you can usually keep the same epilepsy medicine times.1
Contact your epilepsy team if seizures become more frequent or change in type, even if you aren’t sure whether Foundayo is responsible.
How to eat regularly and avoid dehydration
Foundayo reduces appetite, which can lead some people to skip meals or eat too little because they simply don’t feel hungry.
However, we recommend eating three balanced meals a day, even if you’re not hungry, to ensure you’re providing everything your body needs to function well while losing weight on the drug.
We recommend eating a diet based on whole foods that contains enough protein, fibre, fat, and complex carbohydrates, and limits ultra-processed foods.
Use the Second Nature balanced plate as a guide: half non-starchy vegetables, a quarter protein, a quarter complex carbohydrates, and a portion of healthy fat.
If you don’t feel hungry, try meals that are easier to digest and less likely to make you feel uncomfortable, like scrambled eggs on toast with spinach, yoghurt with berries, muesli and nuts, or a smoothie.
Skipping meals can trigger seizures in some people, so it’s essential to maintain this pattern of eating three meals a day.
Nausea, vomiting, and diarrhoea can lead to dehydration. Sip fluids regularly and contact your prescriber if you’re struggling to keep fluids down.1
Some people use a ketogenic or modified Atkins diet as part of specialist epilepsy treatment. Don’t change that diet to match general GLP-1 advice.
Second Nature’s guidelines broadly apply to most people to support weight loss and overall health, but can be adapted to suit all scenarios. For example, by removing the portion of complex carbohydrates and increasing fat intake if on a ketogenic diet for epilepsy.
If you’ve been assigned a ketogenic diet, ask the epilepsy dietitian and Foundayo prescriber to agree how you will maintain the treatment safely while on Foundayo.
Sleep, alcohol, and exercise with epilepsy
Tiredness, stress, and alcohol can trigger seizures for some people. Experiencing side effects or skipping meals during the first few weeks on Foundayo can make it harder to keep sleep, meal, and medicine times consistent.4
Keep sleep and medicine times as consistent as possible during the first few weeks. If fatigue is affecting your routine, speak to your prescriber before increasing the Foundayo dose.
Alcohol can worsen nausea and may affect seizure control. If you drink, follow the limits agreed with your epilepsy team.
Most people living with epilepsy can be physically active, although the safest options depend on seizure type and current level of control. Follow any activity plan from your epilepsy team.
Walking and resistance exercises at home can be easier to manage safely than swimming, climbing or exercising alone near traffic.
Epilepsy can also affect mood, confidence, and social life. Tell your Foundayo prescriber if starting a weight-loss medicine increases anxiety about seizures, side effects, or eating.
Contraception and pregnancy
Foundayo may make oral hormonal contraception less reliable. The UK prescribing information advises switching to a non-oral method or adding a barrier method for 30 days after starting Foundayo and for 30 days after every dose increase.1
Arrange contraception with your epilepsy team before starting Foundayo if you take valproate. Valproate can seriously harm an unborn baby and is subject to a pregnancy prevention programme for women who could become pregnant.5
Foundayo shouldn’t be used during pregnancy or breastfeeding. Stop it at least three weeks before a planned pregnancy.1
Discuss contraception with your epilepsy specialist and Foundayo prescriber before treatment starts. Don’t stop valproate or another anti-seizure medicine because you’re planning a pregnancy without specialist advice.
Symptoms and seizure changes to report
Contact your epilepsy team or prescriber promptly if:
- you vomit after an anti-seizure dose and don’t know whether to repeat it
- you can’t keep your medicine or fluids down
- your seizures become more frequent, last longer or change in pattern
- you develop new confusion, unsteadiness, double vision or unusual drowsiness
- you use oral contraception and haven’t arranged additional protection
Call 999 for a seizure lasting longer than five minutes, repeated seizures without recovery, serious injury, breathing difficulty, or if the person’s usual emergency plan says to do so.4
Frequently asked questions
Can I take Foundayo with carbamazepine?
The UK prescribing information advises avoiding the combination. Carbamazepine reduced the total amount of orforglipron in the bloodstream over time by 82% in an interaction study, which may stop Foundayo working properly.1
Don’t stop or change carbamazepine to take Foundayo. Your neurologist and weight-management prescriber need to discuss other options.
Can I take Foundayo with lamotrigine?
Lamotrigine isn’t listed as a direct interaction in the Foundayo licence. However, the combination hasn’t been studied specifically, and vomiting could prevent an oral dose from being fully absorbed.
Ask your neurologist or pharmacist whether your seizure pattern or current dose means you need additional monitoring.
Does Foundayo lower the seizure threshold?
The Foundayo prescribing information and trial results don’t describe lowering the seizure threshold, and orforglipron hasn’t been tested directly in an epilepsy trial.
Studies of other GLP-1 medicines haven’t found a higher seizure risk, although they can’t show whether Foundayo reduces seizures.2,3
What should I do if I’m sick after taking my epilepsy medicine?
Contact your pharmacist, neurologist or epilepsy specialist nurse for advice.
Don’t take a second dose unless a clinician tells you to.
Can I take Foundayo if I use valproate?
Valproate isn’t listed as a direct Foundayo interaction. You still need a specialist medication review if pregnancy is possible because Foundayo can make oral hormonal contraception less reliable and valproate can seriously harm an unborn baby.1,5
Take home message
Foundayo may be suitable if you have epilepsy, but the UK licence advises avoiding it with carbamazepine and phenytoin because both can substantially reduce the amount of Foundayo in the bloodstream.
Other anti-seizure medicines need an individual review, even when no direct interaction is listed.
Keep your anti-seizure routine consistent, agree on a plan for what to do if you’re sick, and track changes in seizure control when starting Foundayo and after dose increases. Don’t stop an epilepsy medicine in order to start Foundayo.
Second Nature combines GLP-1 medication with structured support from registered dietitians and nutritionists.
A peer-reviewed service evaluation found that active subscribers lost an average of 19.1% of their body weight at 12 months, with 77.7% losing at least 10%.6
Second Nature's Mounjaro and Wegovy programmes
Second Nature provides Mounjaro or Wegovy as part of our Mounjaro and Wegovy weight-loss programmes.
Why choose Second Nature over other medication providers, assuming you're eligible?
Because peace of mind matters.
We've had the privilege of working with the NHS for over eight years, helping people across the UK take meaningful steps toward a healthier, happier life.
Our programmes are designed to meet people where they are, whether that means support with weight loss through compassionate one-to-one health coaching, or access to the latest weight-loss medications (like Mounjaro and Wegovy) delivered alongside expert care from a multidisciplinary team of doctors, psychologists, dietitians, and personal trainers.
At the heart of everything we do is a simple belief: real, lasting change comes from building better habits, not relying on quick fixes. We're here to support that change every step of the way.
With over a decade of experience, thousands of lives changed, and a long-standing record of delivering programmes used by the NHS, we believe we're the UK's most trusted weight-loss programme.
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