How to Switch to Foundayo from Other GLP-1 Medications

Can you switch to Foundayo from another GLP-1?

Yes. You can switch to Foundayo (orforglipron) from another glucagon-like peptide-1 (GLP-1) weight loss medication.

What Foundayo is, in short: a daily oral GLP-1 medication that helps regulate appetite. Eli Lilly makes Foundayo, the same company behind Mounjaro injections.

The Food and Drug Administration (FDA) approved Foundayo in April 2026. Orforglipron is prescribed to adults with obesity and to overweight adults who also have a weight-related health condition. The Medicines and Healthcare products Regulatory Agency (MHRA) has not yet approved it for the UK. Until then, this Foundayo switching guide mainly draws on US prescribing data and trial evidence.

Who is Foundayo for?

Weekly injection users of Wegovy or Mounjaro may want daily oral pills to avoid needles. Daily users of Saxenda or Nevolat injectables have an even stronger case.

A weekly jab is one thing – a daily jab is another. Until now, injections have been the only option for people who need GLP-1 support with weight loss and appetite control. Patients have tolerated them, but many dread the needles. A daily pill will sit a lot easier with some patients.

Oral Wegovy users have a different reason to consider Foundayo. Novo Nordisk’s Wegovy pill must be taken first thing on an empty stomach. No more than 120 mL of water. Then wait at least 30 minutes before eating, drinking, or taking any other tablets. Foundayo has none of those rules. You can take it at any time of day. No food or water restrictions.

Who shouldn’t switch?

Switching is not the right move for everyone. If your current GLP-1 is working well, side effects are manageable, and you are reaching your weight loss goals, there is no clinical reason to change. Foundayo is a useful option for people who can’t take their current medication, can’t tolerate it, or want to come off injections. For people doing well on their current treatment, switching is not necessary.

What is the washout period?

If you are using a weekly injection, you can switch to Foundayo one week after your last injection. With the Wegovy pill, you can start Foundayo the day after your last pill. Two GLP-1s working at once increase overlapping gut side effects, like nausea and reflux. The Foundayo prescribing information says not to take it with another GLP-1 receptor agonist medicine.

Timing mainly depends on how long it takes for half a dose to leave your body. Semaglutide (in Wegovy and the Wegovy pill) can stay in your system for five to seven weeks after your last dose. 

Tirzepatide (Mounjaro) clears in about four weeks. Liraglutide (Saxenda or Nevolat) in two to three days. The rule of thumb is to take your first Foundayo dose when your next injection or tablet is due.

The most common Foundayo starting dose is low. Your prescriber will give you a recommended dose to switch to. Overlap with any leftover injection medication is unlikely to cause major problems, though direct data is limited. If your current GLP-1 has been causing ongoing side effects, contact your prescriber before switching.

What dose do you start on after switching?

Most people switching to Foundayo start at 0.8 mg once daily, the lowest available dose. Then step up monthly through 2.5 mg and 5.5 mg. The dose can increase further to 9 mg, 14.5 mg, or 17.2 mg, with at least 30 days between each step. Maximum: 17.2 mg daily.

Foundayo’s prescribing information has no specific guidance for an orforglipron switch from another GLP-1. If you have been on an injectable GLP-1 for several months and are tolerating it well, you can request a higher starting dose. This includes the highest doses of Wegovy or Mounjaro. Our clinical team reviews each request.

With Simple Online Healthcare, our clinical team reviews your dose history before each step. You need at least 30 days at your current dose to move up.

What should you expect during the transition?

The first month or two of changing to Foundayo will feel familiar if you have been on a GLP-1 before. Expect some appetite wobble in the first weeks. Nausea is the most common side effect, especially during dose increases. 

In the ATTAIN-1 phase 3 trial, roughly four in ten people on the higher doses had nausea. Vomiting and diarrhoea were less common. About 1 in 10 people on the highest dose of Foundayo in the trial stopped taking it because of side effects, compared with around 1 in 40 on placebo.

Weight loss may feel slower in the early weeks than it did on injections. This is more noticeable if you were previously on a higher dose of Wegovy or Mounjaro. In the same trial, people on the highest tested dose of orforglipron lost an average of 12.4% of their body weight after 72 weeks. At the lowest tested dose: around 7.5%.

If you switched from Wegovy because it stopped helping, Foundayo works on the same appetite hormone. Your body responds in much the same way. You will probably see similar results.

Mounjaro works differently. It targets two appetite hormones, GLP-1 and GIP. Foundayo only targets the glucagon-like peptide-1 receptor. If you switch from Mounjaro to Foundayo, you may see less weight loss because you lose the GIP effect.

Two other patterns come up in clinical practice when patients switch between GLP-1 treatments. Hunger often returns for a few days while patients build up to an effective dose of their new GLP-1. 

The same will likely apply when switching to Foundayo. Sticking to it is the second pattern. A weekly injection is one decision a week. A daily tablet is seven. A missed pill is a missed pill, but a missed week is a setback.

Weight regain after changing GLP-1 medications is one of the most common worries patients raise. Foundayo has only been available since April 2026, so real-world data on switching is still thin. But whether your weight holds will largely depend on your maintenance dose and how consistently you take Foundayo – what you eat matters too.

When should I see a doctor?

Most side effects when moving to Foundayo are mild and settle within a few weeks. Some symptoms need urgent attention:

• Severe or persistent nausea or vomiting that stops you from keeping fluids down
• Severe abdominal pain in the upper belly that does not ease (possible pancreatitis)
• Pain in the upper right side of your belly with fever, yellow skin, or pale stools (possible gallbladder problem)
• Dehydration signs: dizziness, dark urine, faintness
• A new neck lump, hoarseness, or trouble swallowing
• Severe allergic reaction symptoms: rash, swelling of the face or throat, difficulty breathing

Call 999 or go to A&E for severe abdominal pain or sudden trouble breathing. Do the same if you have signs of a serious allergic reaction. NHS 111 can help if you are not sure how urgent something is.

If you have type 2 diabetes and take insulin or a sulfonylurea, Foundayo can cause low blood sugar (hypoglycaemia). Symptoms include shakiness, sweating, and feeling lightheaded. 

You should not use Foundayo if you use medications that induce or inhibit CYP3A4 enzymes.

Foundayo is only currently approved for weight loss. If you are switching from a GLP-1 you take for type 2 diabetes, the same precaution applies.

Key takeaways

• Switching GLP-1 to Foundayo is possible, with no formal washout in most cases.
• Starting dose: usually 0.8 mg daily. Higher starting doses possible with clinical team review for experienced GLP-1 users. Maximum: 17.2 mg.
• Do not take Foundayo with another GLP-1 medication unless your clinical team specifically advises it.
• If you have been on a GLP-1 before, the change to Foundayo will feel familiar in the first month. Common side effects: nausea and reduced appetite, mostly during dose steps.
• Foundayo is FDA-approved to support weight loss in the United States. MHRA review for the UK is pending. Our team will offer Foundayo once it is licensed here.

References

Orforglipron, an Oral Small-Molecule GLP-1 Receptor Agonist for Obesity Treatment, New England Journal of Medicine, 2025 [Accessed 6 May 2026]

Foundayo (orforglipron) Highlights of Prescribing Information, Eli Lilly and Company, 2026 [Accessed 6 May 2026]

FDA Approves First New Molecular Entity Under National Priority Voucher Program, US Food and Drug Administration, 2026 [Accessed 6 May 2026]

Lilly’s orforglipron helped people maintain weight loss after switching from injectable incretins to oral GLP-1 therapy in first-of-its-kind Phase 3 trial, Eli Lilly and Company press release, 18 December 2025 [Accessed 6 May 2026] 

Wegovy 2.4 mg FlexTouch solution for injection in pre-filled pen — Summary of Product Characteristics, electronic medicines compendium, Novo Nordisk, 2025 [Accessed 6 May 2026]

Mounjaro KwikPen 2.5 mg, 5 mg, 7.5 mg, 10 mg, 12.5 mg, 15 mg solution for injection in pre-filled pen — Summary of Product Characteristics, electronic medicines compendium, Eli Lilly, 2025 [Accessed 6 May 2026]

Nevolat 6 mg/ml solution for injection in pre-filled pen — Summary of Product Characteristics, electronic medicines compendium, Zentiva, 2024 [Accessed 6 May 2026]

Wegovy (semaglutide) tablets — Highlights of Prescribing Information, US Food and Drug Administration, Novo Nordisk, 2025 [Accessed 6 May 2026]

Authorship

Authored by Shereen Amin

Pharmacist Independent Prescriber & Medical Writer
GPhC: 2073003
Shereen is a Pharmacist Independent Prescriber and medical writer with over ten years' experience across NHS primary care, digital health and specialist services. She writes evidence-based health content for Simple Online Pharmacy, turning complex clinical information into guidance patients can actually use.

Medically Reviewed by Zahra Qureshi

Senior Pharmacist
GPhC: 2216331
Zahra began her pharmacy career in community pharmacy, building a strong foundation in patient care and medication safety. She joined Simple Online Pharmacy as a locum pharmacist and quickly progressed to a senior role, supporting the pharmacy and operations teams. Zahra is passionate about ensuring patient guidance is safe, clinically sound, and easy to understand, making a positive difference to patients’ lives.