9 common Foundayo side effects and how to manage them

Few things are guaranteed in life besides taxes and the possibility of side effects from prescription medications, including Foundayo (orforglipron). As with other GLP-1s, Foundayo side effects typically show up within the first few weeks of starting the weight loss pill and when increasing your dosage. They’re also largely digestive in nature, and commonly include:

1. Nausea 

2. Constipation

3. Diarrhea

4. Vomiting 

5. Indigestion, abdominal pain, and bloating

6. Headache

7. Fatigue

8. Gas, burping, and heartburn

9. Hair loss

Ahead, this guide covers the common Foundayo side effects in detail, why they can happen, and how to manage them. 

Like other GLP-1 medications, Foundayo commonly causes gastrointestinal (GI) side effects. This is because it slows gastric emptying (i.e. the movement of food through your gastrointestinal tract) and lowers your appetite. 

These side effects are most common when you first start the medication or when your dosage is increased. Fortunately, they typically go away over time as your body adjusts to the medication.

Here are nine of the most common side effects of Foundayo. 

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1. Nausea 

Like other GLP-1 medications, Foundayo commonly causes nausea. In clinical trials of the drug, up to 35% of people experienced nausea:

• 26% on 5.5 mg dose 

• 34% on 9 mg dose

• 35% on 17.2 mg dose

This side effect tends to be more common during the dose escalation process. Luckily, though, it’s typically temporary and only mild to moderate in severity. So much so, in fact, nausea was “ generally mild, transient, and rarely led to discontinuation” of orforglipron, according to a scientific review. 

Some research suggests orforglipron may be more likely to cause nausea compared to other GLP-1s, possibly because of how quickly it’s absorbed. But actual rates of nausea vary among studies. 

How to manage nausea:

• Avoid greasy, high-fat foods 

• Eat smaller, more frequent meals 

• Eat more slowly and mindfully 

2. Constipation

Constipation is the second most common GI side effect of Foundayo, affecting up to 27% of people in clinical trials. 

In fact, a 2025 meta-analysis that compared the efficacy and safety of 12 GLP-1 drugs found that orforglipron had the highest incidence of nausea, constipation, and diarrhea. 

Foundayo can also make you feel fuller sooner, so you may eat and drink less. While this can promote weight loss, it can also make it harder to pass stool — especially if you’re not staying hydrated and filling up on fiber. 

Adding insult to injury is nausea — or, well, one of the strategies to ease nausea on Foundayo. Eating bland, low-fiber foods can reduce the bulk that helps keep your number twos moving through and out.  

How to manage constipation:

• Eat high-fiber foods, such as legumes (e.g. beans, lentils), fruits and veggies, and whole grains (e.g. oats) 

• Drink more water throughout the day 

• Get more exercise to help move along your bowels

3. Diarrhea

In clinical trials, up to 1 in 4 (25%) people experienced diarrhea while taking Foundayo. Like nausea, diarrhea seems to be more common with orforglipron than other GLP-1s, based on its higher risk compared to placebo. Again, diarrhea is most likely when starting Foundayo or after a dose increase, as the body adjusts to its effects on digestion. 

Slowing down the rate at which food moves through your gut can cause more trips to the bathroom for some (and, yes, fewer trips for others). 

GLP-1s are also known to change the amount of fluid secreted into the gut. And more fluid in the gut can lead to more watery stools. 

How to manage diarrhea:

• Stay hydrated by drinking lots of fluids, such as water, tea, and broth 

• Eat a bland diet, or BRAT diet, to help firm up your stools

• Steer clear of fried or greasy food and dairy 

4. Vomiting 

Foundayo may also cause vomiting, which again is related to the drug slowing gastric emptying. Keeping food in the stomach longer can increase the risk of vomiting, especially if you’re experiencing nausea. 

This side effect affected almost one-fourth of people taking Foundayo in clinical trials. 

How to manage vomiting: 

• Consume bland foods like toast, rice, and bananas

• Stay hydrated by drinking plenty of water and clear liquids 

• Eat smaller portions

5. Indigestion, abdominal pain, and bloating

Additional GI side effects of Foundayo include indigestion, abdominal pain, and bloating. These symptoms occurred in 8%--14% of people taking Foundayo in clinical trials. More specifically:

Like other GI side effects, these side effects are usually mild to moderate. Therefore, if you develop severe abdominal pain, with or without nausea or vomiting, or pain that radiates to your back, contact your healthcare provider. These may be signs of a more rare but serious side effect, such as pancreatitis or gallstones. 

How to manage indigestion, abdominal pain, and bloating:

• Avoid foods and drinks that can irritate your stomach, such as spicy foods, dairy, and carbonated beverages

• Chew food more thoroughly and eat slowly (i.e. practice mindful eating)

• Eat smaller, more frequent meals 

6. Headache

Another common side effect of Foundayo, headache was reported by 8%--9% of people in clinical trials. 

Headaches may occur due to a reduced appetite, which can lead to drops in blood sugar levels. They can also happen if you’re dehydrated — a common result of vomiting and diarrhea (two other Foundayo side effects) and reduced appetite (a mechanism of Foundayo). 

How to manage headaches:

• Drink plenty of fluids throughout the day (water-rich fruits and vegetables can also help) 

• Try not to skip meals and eat regularly 

• Get adequate sleep (general recommendation is 7–9 hours per night)

• Ask your healthcare provider about over-the-counter (OTC) pain relievers, such as Tylenol (acetaminophen) or Advil (ibuprofen)

7. Fatigue

In clinical trials, 6%--9% of people taking Foundayo reported fatigue. 

Why? Similar to headaches, fatigue can occur on Foundayo because of changes in your eating and drinking habits during treatment. Think of it this way:

• A reduced appetite can lead you to consume fewer calories 

• Certain side effects can lead you to lose fluids and become dehydrated 

• The medication in and of itself can lead to a drop in blood sugar 

All of these effects can leave you feeling tired, run down, and, well, fatigued while taking Foundayo. 

How to manage fatigue:

• Get adequate sleep (general recommendation is 7–9 hours per night)

• Stay hydrated by drinking plenty of water throughout the day 

• Try not to skip meals and eat regularly 

• Increase physical activity (which has been shown to boost energy)

8. Gas, burping, and heartburn

If you feel particularly burpy, farty, or like your throat is burning on Foundayo, you’re likely not imagining it. These symptoms occurred in 5%--8% of people taking Foundayo in clinical trials. More specifically:

Because Foundayo slows gastric emptying, it may also cause gas, burping, and heartburn. While keeping food in the stomach longer makes you feel fuller, it can also give your gut bacteria more time to break down food. This can lead to more gas in your GI tract. 

Heartburn occurs when acid flows up from the stomach toward the throat. Like other common side effects, it’s likely related to the drug’s effects on digestion. Having food and stomach acid (which helps break down food) sit in the stomach longer can cause a buildup of acid, leading to heartburn. 

How to manage gas, burping, and heartburn:

• Limit carbonated beverages and chewing gum

• Avoid foods that can trigger reflux symptoms, such as spicy, fried, and acidic foods

• Chew food slowly and thoroughly before swallowing

• Eat smaller portions 

• Try to stay upright after eating (i.e. avoid lying down directly following a meal)

• Consider short-term OTC heartburn medications, such as Tums, Pepcid (famotidine), or Prilosec (omeprazole)

9. Hair loss

Affecting just 4%--5% of people in clinical trials, hair loss is the least common Foundayo side effect on our list. Across two studies, hair loss affected more female participants than male participants (7% females vs. 0.9% males). 

Hair loss may be the result of rapid weight loss — such as that often occurs on Foundayo. Losing weight quickly can trigger telogen effluvium (TE), an often temporary condition that causes sudden hair shedding. Hair loss from weight loss usually stops on its own once your weight levels off. 

Alternatively, because Foundayo reduces your appetite, you will likely take in fewer calories. This can lead to nutrient deficiencies, especially among those that support healthy hair. Without the right nutrients, you can experience hair loss. 

How to manage hair loss:

• Consume a healthy, nutrient-dense diet with hair-friendly vitamins and minerals (e.g. biotin, zinc, iron, vitamins A, C, and E)

• Prioritize protein (which can help strengthen your strands and your muscles, which can also be affected by rapid weight loss) 

• Control side effects that can impact your nutrient intake 

• Consult your healthcare provider about prescription and OTC hair loss options (e.g. topical minoxidil, oral minoxidil, finasteride)   

It depends. Common Foundayo side effects typically begin early in treatment and during dosage increases. (Remember: Foundayo, like other GLP-1s, follows a titration schedule during which you gradually increase your dose over several months until arriving at a maintenance dose that works for you). 

Foundayo side effects can last up to a few weeks as your body gets used to the medication, or they may come and go throughout the dose titration process. 

To reduce the risk of side effects, be sure to follow the recommended dosing schedule set forth by your healthcare provider. If you’re experiencing bothersome side effects or those that don't go away, talk to your healthcare provider. In rare cases, Foundayo can cause long-term side effects. 

While rare, serious side effects can occur while taking Foundayo, including: 

• Thyroid cancer: Foundayo has a boxed warning about the potential risk of thyroid tumors. If you develop a lump or swelling in your neck, hoarseness, trouble swallowing, or shortness of breath, tell your healthcare provider. 

• Pancreatitis (inflammation of the pancreas): Symptoms include severe abdominal pain that sometimes moves to your back, nausea, fever, and vomiting.

• Gallbladder problems: Symptoms include upper stomach pain, fever, clay-colored stools, and yellowing of your skin or eyes.  

• Kidney problems: Foundayo can cause vomiting and diarrhea, which can lead to dehydration. This can cause kidney problems or worsen existing kidney issues. 

• Hypoglycemia (low blood sugar): Foundayo can lower your blood sugar levels. If you take certain diabetes medications, such as insulin or sulfonylureas, your blood sugar can drop too low. Symptoms include dizziness, lightheadedness, sweating, confusion, and blurry vision. 

• Serious allergic reactions: Foundayo can cause serious allergic reactions. Get medical help right away if you have trouble breathing, swelling in your lips, tongue, or throat, or hives. 

• Pulmonary aspiration (when food or liquid gets into the lungs): This is particularly a risk if you’re scheduled for a surgery or procedure that requires anesthesia. Because Foundayo slows the movement of food through your GI tract, food stays in your stomach longer. This can increase the risk of it getting into your lungs while under anesthesia. 

• Vision changes in people with diabetic retinopathy: Symptoms such as blurry vision, floaters, or spots can occur. 

Notably, the US Food and Drug Administration (FDA) is requiring the manufacturer of Foundayo to conduct long-term studies to monitor potential safety concerns, including thyroid cancer, liver injury, and major heart-related problems, as these risks are not yet fully understood.

Foundayo isn’t right for everyone. You shouldn’t take Foundayo if:

• You are pregnant,  planning to get pregnant, or breastfeeding

• You have severe liver problems or gastrointestinal conditions, such as severe gastroparesis

• You or your family has a history of certain thyroid cancers, such as medullary thyroid carcinoma and multiple endocrine neoplasia syndrome type 2 (MEN 2)

• You are allergic to any ingredients in Foundayo

Mild to moderate side effects may occur while you are taking Foundayo, especially those of a digestive nature. But if you experience very bothersome or severe side effects that don’t go away, it is a good idea to contact a healthcare provider. 

Depending on your specific symptoms and their severity, your provider may recommend additional management strategies or adjust your Foundayo dosage until your body adjusts. If necessary, they may even propose switching to a different medication. 

When taking a weight loss treatment, such as Foundayo, you’ll likely be in constant communication with your provider — at least that's the case on Ro. This allows you to report or ask any questions about side effects. (As a Ro Body member, for example, you get unlimited messaging access with your provider so you can chat in between monthly visits.) 

Nevertheless, it is important to contact your healthcare provider if you:  

• Develop signs or symptoms of an allergic reaction, including trouble breathing, hives, or swollen lips, tongue, or throat

• Develop signs or symptoms of thyroid cancer, such as a lump or swelling in your neck, a hoarse voice, or trouble swallowing

• Have persistent constipation or difficulty passing gas

• Develop severe or persistent stomach pain

• Have nausea, vomiting, or diarrhea that will not go away

• Have clay-colored stools or yellowing of your skin or eyes

• Become pregnant

• Have an upcoming surgery or procedure that requires you to be sedated or put to sleep (anesthesia)

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Foundayo is a convenient and effective tool for weight loss. But like all medications, it can cause side effects. Keep the following in mind about orforglipron side effects: 

• Like other GLP-1s, the most common side effects of Foundayo are GI issues. These include nausea, diarrhea, vomiting, and constipation. 

• Fortunately, Foundayo side effects are usually mild to moderate in severity. They tend to occur early on during treatment and go away as your body adjusts to the medication. 

• Lifestyle changes can help ease your symptoms. Examples include eating smaller portions, avoiding foods that upset your stomach, and drinking plenty of water. 

• Foundayo can also cause serious side effects, like pancreatitis and hypoglycemia (low blood sugar). However, these are usually rare. 

• Contact your healthcare provider if you develop any severe or bothersome side effects.