Foundayo Side Effects: What To Expect Before You Begin Treatment

If you're considering GLP-1 treatment, you're not alone. A 2025 study found that nearly 1 in 10 adults in the UK had either recently used a GLP-1 medication to support weight loss, or planned to soon. [1]

If you're exploring your options, you may have heard of a treatment which will soon be available by prescription in the UK: Foundayo™.

In this article, we'll explain which side effects you may experience if you're eligible for treatment with Foundayo. We'll also explore how treatment with Foundayo compares to other GLP-1s currently available on the market, to help you make the right choice for your care.

Article Summary:

• Foundayo is a once-daily oral GLP-1, which is prescribed for weight management.
• Foundayo contains the active ingredient orforglipron, which features a different molecular structure to other GLP-1 treatments currently available. This means orforglipron can be taken as a daily tablet, with no fasting or injections required.
• Orforglipron side effects most commonly include digestive side effects like nausea, vomiting, diarrhoea and constipation. These are often mild, short-term and may be resolved with gentle management and over-the-counter (OTC) remedies. However, it’s important to be aware of all possible side effects (including the rarer, but more serious ones). If you have concerns about any side effects, speak to your healthcare provider.

What is Foundayo and how does it work?

Foundayo is a type of medication called a glucagon-like peptide-1 (GLP-1) receptor agonist.

GLP-1 is a hormone our body naturally releases after eating food.

GLP-1 medicines work by mimicking this hormone, to:

• Suppress your appetite
• Slow your digestion
• Regulate your blood sugar levels [2]

The result? You're more likely to feel fuller, for longer. GLP-1 treatment may also help to reduce "food noise" (intrusive and persistent thoughts about eating, even when you're not hungry). [3]

When paired with a healthy, balanced diet and increased daily movement, GLP-1 treatments like Foundayo may support weight loss and weight management. [2]

Foundayo is taken once daily as an oral tablet.

Is Foundayo right for me?

You may be eligible for Foundayo if you live with either obesity, or overweight with a weight-related medical condition (like type 2 diabetes or high blood pressure).

You shouldn't take Foundayo if you're pregnant, breastfeeding or trying to conceive. And you should never take Foundayo if you, or any of your family, have ever had a type of thyroid cancer called medullary thyroid cancer (MTC), or if you have an endocrine system condition called multiple endocrine neoplasia syndrome type 2 (MEN 2). [4]

Before taking Foundayo, be sure to share any medical conditions you're experiencing (or have experienced in the past) with your clinician. This will help them to make a safe, informed choice about your treatment options. [4]

Foundayo will only be available via prescription from a registered clinician. They'll be able to assess your current health and medical history, to decide your eligibility. They'll also be able to explain more about weight loss treatment, possible side effects and whether Foundayo is the right choice for you.

How effective is Foundayo?

In one clinical trial, individuals taking the highest dose of Foundayo lost an average of 12.4% of their body weight in 72 weeks.* [5] However, individual results may vary. Treatment should also be paired with positive, long-term lifestyle changes to help you reach and maintain your goals. [6]

How does Foundayo differ from other GLP-1 treatments?

There are a few features of Foundayo that differentiate it from other GLP-1 treatments currently available:

Active ingredient: The active ingredient in Foundayo is orforglipron.

Unlike other GLP-1 treatments (where the active ingredients are large peptide molecules that may require injection or fasting before use), orforglipron is a small molecule-based non-peptide. This means it's not broken down by stomach acid in the way other GLP-1 treatments are. [2]

How it's taken: Because of this structural difference, Foundayo can be taken as a daily pill without fasting. No injection required. [4]

How often it's taken: Like other oral GLP-1 treatments, Foundayo is taken once daily as a pill.

Fasting requirements: Unlike other oral GLP-1 treatments, you don't need to fast for 30 minutes before taking Foundayo.

It has no food, drink or timing restrictions, so you can take it at a time that's convenient for you. [4] We recommend taking it at the same time each day, to support treatment consistency and prevent a missed dose.

Storage: Foundayo tablets should be stored at room temperature (unlike injectable treatments, which should be stored in the fridge before first use). [7]

Side effects: Side effects are common during all types of GLP-1 treatment. Read on to learn more about what these may be, and how to help manage them.

Foundayo side effects

Common side effects:

Gastrointestinal side effects are the most likely when taking Foundayo. Very common side effects at the maximum dose may include:

• Nausea
• Diarrhoea
• Vomiting
• Constipation
• Indigestion [5]

Other common side effects may include:

• Headache
• Bloating
• Stomach pain
• Burping
• Acid reflux
• Flatulence
• Hair loss,
• Feeling tired (fatigue) [5]

If you experience any persistent or uncomfortable side effects, talk to your healthcare provider.

Serious side effects:

Although they're less common, it's important to be aware of the potential serious side effects of Foundayo. These include:

• Inflammation of the pancreas (acute pancreatitis). If you experience:
  • Severe pain underneath your right ribcage that may spread to your shoulder or back
  • Vomiting
  • A high temperature
  • A rapid heartbeatThis may be acute pancreatitis. Stop taking Foundayo and seek immediate medical attention.
• Low blood sugar (hypoglycemia). Your risk for getting low blood sugar may be higher if you use Foundayo with medicines that can cause low blood sugar. Signs of very low blood sugar in someone who is unresponsive or not behaving normally, including:
  • Dizziness
  • Irritability
  • Confusion
  • Rapid heartbeat
• Serious allergic reaction (anaphylaxis):
• Difficulty breathing
• Swelling of the lips, tongue or throat.
• Changes in vision, especially if you have type 2 diabetes. Tell your healthcare provider if you experience any changes in your vision during treatment with Foundayo.
• Gallstones can occur during weight loss treatment, particularly with rapid weight loss. Call 999 or visit A&E immediately if:
  • You have severe pain under your right ribcage that spreads to your right shoulder or back and interferes with normal activities (this may indicate acute gallbladder disease).
  • The pain is accompanied by vomiting or a high temperature.
  • You experience a rapid heartbeat.
• Foundayo may increase the chance of food getting into your lungs during surgery, or any other procedures that require anaesthesia. Tell your healthcare provider that you're taking Foundayo before you're scheduled to have surgery. [4, 5]

These are not all the possible side effects of Foundayo. If you have any concerns, it's worth discussing them with your healthcare provider.

When are Foundayo side effects most common?

You're more likely to experience side effects when you first begin treatment, and every time your dose increases (we call this "titration"). [8] However, if your side effects are persistent or particularly uncomfortable, it's worth speaking to your healthcare provider. They may be able to adjust your dose to one that's more tolerable for you, or recommend appropriate over-the-counter (OTC) remedies.

Tips for managing Foundayo side effects

If you experience any serious side effects of Foundayo, it's really important you seek immediate medical help.

Fortunately, most side effects are mild, and may be managed at home and with OTC treatments. Here are our tips for navigating the most common side effects associated with Foundayo:

Nausea and vomiting:

Nausea may affect anywhere between 29-34% of people who take Foundayo. [5] 13-24% may also experience vomiting. [5] To manage these side effects, you can try to:

• Eat smaller, more frequent meals throughout the day. Remember that Foundayo can be taken with or without food (and there are no fasting requirements), so it's worth seeing if taking it with a meal helps you feel less nauseous.
• Avoid high-fat and greasy foods, as well as foods with a strong smell.
• Vomiting and diarrhoea may cause a loss of fluids (dehydration). If left untreated, this may cause kidney problems. [9] Drink plenty of water, little and often. This may help reduce any feelings of nausea, and also minimise the risk of vomiting. The NHS recommends we aim for 6-8 glasses of fluids throughout the day. [10]
• Sip on ginger tea, or take a ginger supplement, to help manage nausea. [11]

Abdominal pain (stomach pain), heartburn and indigestion:

Indigestion may affect 13-14% of people taking Foundayo [5]. Try to:

• Stay upright for at least 30 minutes after eating, and avoid eating too close to bedtime.
• Avoid fatty, spicy foods. Highly acidic foods may also trigger discomfort.

Constipation:

22-25% of people taking Foundayo may experience constipation. [5] If you experience constipation, you could try:

• Increasing your daily movement to help move your bowels. [12] Go for a gentle walk to stimulate bowel movements.
• Drinking plenty of water, little and often.
• Gradually adding more fibre to your diet. These can include whole grains, pulses and legumes (like beans and lentils) and fruit. The NHS recommends we aim for 30g a day of dietary fibre. [13]
• Dietary supplements, like psyllium husk. These may help to ease constipation. [14] Be sure to speak to your healthcare provider before you add any supplements to your routine.
• Glucomannan supplements. It’s a type of fibre that absorbs water, which may make stools softer and easier to pass.

Diarrhoea:

21-23% of people who take Foundayo may experience diarrhoea. [5] Here's what you can do to manage the symptoms:

• Drink plenty of fluids (like water and herbal teas) to prevent dehydration.
• Eat small, frequent meals.
• Rest and allow your body time to recover.
• Consider oral rehydration salts to replace lost fluids and electrolytes.
• Take paracetamol to help with associated discomfort.

Bloating, gas and belching:

7-9% of people who take Foundayo may experience bloating. Burping and flatulence were also reported in 4-6% of those taking Foundayo. [5] To reduce these symptoms, try:

• Avoiding fizzy drinks, which could make bloating feel worse.
• Eating and drinking more slowly.
• Avoiding foods that may trigger bloating (these could include alliums like onions and garlic, or dairy), until your symptoms have resolved.

Headaches and feeling tired:

9-10% of people taking Foundayo may experience headaches and fatigue (feeling tired). [5] These tips may help:

• Drink plenty of water to stay hydrated, prevent headaches and support energy levels. [15]
• Rest where possible. The NHS recommends that adults aim for 7-9 hours of sleep each night. [16]

Hair loss:

Studies suggest that 4-5% of people taking Foundayo may experience hair loss. [9] This is because when we experience a sudden weight loss, it may force our hair follicles into a premature resting and shedding (telogen) phase. [17]

But the good news is that this is usually a temporary side effect, and eating a healthy, balanced diet with plenty of protein may support healthy hair growth. [17, 18] Once the trigger resolves (for example, your weight stabilises and any deficiencies are corrected), hair growth will typically begin again. [19]

For long-term support, hair loss treatments containing active ingredients like minoxidil may encourage stronger, fuller hair. [20]

Weight loss medication is a big step, and it may take time for your body to adjust to treatment. Try to be kind to yourself, and prioritise your wellbeing. Listening to your body, managing your side effects and making any necessary adjustments to your treatment will set you up for long-term success.

Understanding potential side effects is an important part of deciding whether Foundayo is right for you. At MedExpress, we offer online consultations with regular clinical check-ins, and a range of weight loss treatments including Mounjaro Pen, Wegovy Pen, Wegovy Pill and Foundayo (coming soon) and our team can help you find the right treatment for you.

*ATTAIN-1, 72-week study of adults with obesity using orforglipron 36mg alongside lifestyle changes. Individual results vary.

References

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