The Truth About GLP-1 Side Effects: Symptoms, Solutions, and What to Expect
- Jennifer Hardy
- Mar 23
- 8 min read
Updated: 5 days ago
GLP-1 receptor agonists like Ozempic, Wegovy, Mounjaro, and Zepbound have revolutionized weight loss and diabetes management, but they come with some side effects—some minor, some more challenging.
Before I started taking Zepbound, I was horrified by the Reddit forum reports of days filled with explosive diarrhea and violent vomiting. One of my freelance clients even disappeared for a few days, later telling me she was strapped to the toilet for 72 hours.
I decided I was going to investigate these risks and find all the best ways to avoid or limit the impact. Now, I want to share that information with you.
This guide breaks down everything you need to know about GLP-1 side effects, with practical tips to minimize discomfort and maximize results.
What is a GLP-1?
GLP-1 (glucagon-like peptide-1) receptor agonists mimic a hormone naturally produced in the body that helps regulate blood sugar and digestion. These medications slow down how quickly food leaves the stomach, reduce appetite by affecting hunger signals in the brain, and help the pancreas release insulin more efficiently.
Some of the most common GLP-1 medications include:
Semaglutide (Ozempic, Wegovy)
Tirzepatide (Mounjaro, Zepbound)
Liraglutide (Saxenda, Victoza).
These drugs have been life-changing for people struggling with obesity and type 2 diabetes, but because they alter how the body processes food, they often come with a range of digestive and metabolic side effects.
That's why the 2.5mg dose of GLP-1 medications like Mounjaro (tirzepatide) or Zepbound is primarily a starter dose designed to help your body adjust to the medication. It allows your system to gradually adapt to changes in digestion, appetite, and blood sugar regulation while minimizing side effects.
A maintenance dose is the lowest effective amount of a medication taken long-term to sustain results, while a therapeutic dose is the optimal amount needed to achieve full clinical benefits.
While some people stay on low doses for maintenance, most will titrate up to higher doses for full therapeutic effects, depending on their treatment plan and goals.
Why Do GLP-1s Cause Side Effects?
Side effects from GLP-1s occur because these medications fundamentally alter digestion, appetite, and metabolic responses. When food stays in the stomach longer, it can cause nausea or bloating. A reduced appetite may lead to low energy or nutrient deficiencies if you’re not careful.
Some side effects are just part of the adjustment period, while others may persist longer. Understanding why they happen can help you take steps to minimize discomfort.
However, what you eat can also play a big role in how you feel. Eating too much, too little, or the wrong types of food—like greasy, heavy meals—can make nausea, bloating, and fatigue worse.
Bottom line: GLP-1s aren't magic bullets. You still have to make some lifestyle adjustments to get the full benefits while mitigating risks.
Required Disclosure for Medication Side Effects
The FDA requires pharmaceutical companies to list all known side effects of GLP-1 medications in the prescribing information (also called the package insert). These documents include clinical trial data, common and rare side effects, and safety warnings.
You can find the official prescribing information for Ozempic, Wegovy, Mounjaro, and Zepbound on the FDA website or the manufacturer's site. I linked each one in the drug's name for easy access.
Additionally, TV commercials and ads for these medications must include spoken and written disclaimers about possible side effects, per FDA regulations.
The FDA evaluates a drug’s safety and effectiveness by weighing its clinical benefits against potential risks. Approval only happens if the expected health improvements outweigh the likelihood and severity of side effects based on clinical trial data.
What Are the Most Common Side Effects?
Every GLP-1 medication has an official list of potential side effects, which you can find in the prescribing information on the FDA website or the manufacturer’s website.
However, based on real-world experiences, these are the most commonly reported side effects:
1. Gastrointestinal Issues
Nausea and Vomiting – One of the most common side effects, often worse after large meals.
Constipation – Digestion slows down, which can lead to harder stools.
Diarrhea – Some people experience the opposite effect, especially in the early weeks.
Bloating and Gas – A feeling of fullness that lingers long after eating.
Heartburn and Acid Reflux – Food sitting in the stomach longer can lead to discomfort.
"Sulphur Burps" – These hit me hard. They smell and taste like rotten eggs due to hydrogen sulfide gas in the stomach
2. Fatigue and Dizziness
Since GLP-1s suppress hunger, some people unintentionally eat too little, which can lead to low energy and dizziness. Dehydration from loss of fluids can also cause lightheadedness. It's important to stay hydrated with water and electrolytes when taking a GLP-1.
3. Injection Site Reactions
For those using injectable GLP-1s, redness, swelling, or itching at the injection site can occur. Since some versions require consumers to inject themselves at home, proper needle handling and sterilization are critical.
4. Hair Thinning
Rapid weight loss can stress the body, leading to temporary hair shedding. This isn’t caused directly by GLP-1s but rather by nutrient changes and lower protein intake. You can read our article about how important protein is when on a GLP-1 medication.
5. Rare but Serious Side Effects
Severe stomach pain – Could be a sign of pancreatitis.
Gallbladder issues – Rapid weight loss increases the risk of gallstones.
Low blood sugar (for diabetics) – If combined with insulin or other diabetes meds, GLP-1s can increase the risk of hypoglycemia.
If you experience persistent vomiting, sharp abdominal pain, or signs of severe dehydration, seek medical help immediately.
When Are Side Effects Most Likely to Happen?
For most people, side effects are strongest in the first few weeks of starting GLP-1s or after a dose increase.
First 1-2 weeks: Nausea, bloating, and fatigue are most common as the body adjusts.
After each dose increase: Symptoms may return temporarily but typically improve within a week.
After several months: Most people experience fewer side effects, but some (like constipation) can persist without dietary adjustments.
The best approach is to expect some discomfort in the beginning but know that it usually gets better with time.
How to Handle GLP-1 Side Effects Before They Happen
Since I had enough anxiety about getting too sick to work, I learned a lot about how to adjust my body and food routine. It started with taking a probiotic. While I can't be 100% certain that's what helped the most, I know I haven't had really sick days since I started.
A little preparation goes a long way in making GLP-1 side effects more manageable. If you plan ahead, you can avoid the worst of the symptoms.
Start by working five or six small balanced meals into your food day, not the traditional breakfast, lunch, and dinner. Large meals can trigger nausea. Focus on lean protein, healthy fats, and fiber to keep digestion steady.
Staying hydrated helps prevent constipation and bloating. Mix in electrolytes a couple of times a day if you're having tough gastrointestinal side effects. Aim for about six bottles of water (about 2/3 of a gallon) daily. I drink a gallon a day, but I lived in the desert and developed a great habit of drinking water all day long.
Slow down when eating. Rushing through meals can overwhelm digestion and worsen nausea. Since GLP-1s calm the "food noise," eat until you are satiated, not full.
Adding a vitamin B6 supplement can help reduce nausea and fatigue. Since B6 plays a key role in digestion and neurotransmitter function, taking it before symptoms start may help the body adjust more smoothly to appetite and metabolic changes. I started taking B6 three days before my first Zepbound injection, and it crushed my appetite on its own.
Even if you’re not hungry on a GLP-1, skipping meals can backfire—leading to fatigue, dizziness, nausea, and even muscle loss over time. Your body still needs nutrients and protein to function properly. I almost have to force-feed myself 48 hours after each dose. The thought of food makes my stomach turn. However, bone broth has been so helpful in getting nutrients and protein without upsetting my tummy.
The goal is to ease into your GLP-1 treatment with as little disruption as possible.
What to Do When GLP-1 Side Effects Start?
Even with preparation, side effects can still happen. Here’s how to manage them in real time:
Nausea & Vomiting: Ginger tea, peppermint, and bland foods like crackers or toast can help settle the stomach. Some people find relief using motion sickness bands.
Constipation: Increasing fiber slowly, drinking plenty of water, and adding magnesium or chia seeds to the diet can help keep digestion moving.
Fatigue: Eating enough protein and not skipping meals will help prevent energy crashes. If dizziness persists, adding more electrolytes and healthy fats to your diet can help.
Heartburn: Avoid spicy or greasy foods, and try eating earlier in the evening so digestion is complete before bed. I also find that two antacids quickly dispel the burn, when I used to take up to 10 a day.
Hair Thinning: Prioritizing protein intake, collagen supplements, and vitamins like biotin and zinc can help maintain hair health.
If any side effects become severe or don’t improve, consult your healthcare provider. Adjusting your dosage or changing your diet can often make a big difference.
The Ugly & Not-So-Ugly Truth About GLP-1 Side Effects
Everyone’s body reacts differently to GLP-1 medications because of factors like metabolism, gut microbiome, diet, hydration, and overall health. Some people tolerate the meds easily, while others experience stronger side effects due to how their digestive system, hormones, and insulin response adjust to the drug.
Genetics, pre-existing conditions, and even how quickly the dosage increases can also impact the severity and type of side effects someone experiences. That's why you can't assume that if your friend or colleague had a bad experience, you will, too.
As of March 2025, I'm down 45 pounds after three months on Zepbound. My side effects have been mild to moderate. Here's the honest-to-goodness truth about what helped me:
Start taking B6, collagen, and a probiotic before you start your dose.
Keep a journal of side effects. Some people experience issues 48 hours after a dose, others 72 hours later. Once you find the cadence of your "worst" side effects, you can plan life a little better.
For the first month, always be within dashing distance of a private bathroom. That is especially true in the hour after a meal. If you share a bathroom, I recommend getting some Poopouri. (You'll thank me for this tip!)
Expect changes after every dosage increase. Don't give up if weeks one and/or two are bad. Give your body time to adjust.
It should go without saying, but eat healthy and in realistic portions. Remember when those Olestra potato chips promised a fat-free alternative but instead introduced a generation to the term "anal leakage"? If you eat too much greasy, fat-filled food, anal leakage will be but one of many concerns.
Eliminate or greatly reduce soda intake. Soda—especially carbonated and sugary varieties—can worsen nausea, bloating, and blood sugar fluctuations on GLP-1 medications. This exacerbates side effects, especially bloating.
Don't skimp on protein. Talk with a nutritionist about how much protein you'll need while taking a GLP-1. Also, I've heard many stories about how drinking a protein shake an hour before the weekly dose can help with side effects.
Avoid alcohol... for now. Until you know how your body reacts to the GLP-1, don't mix in the blood-sugar impacts of alcoholic beverages.
Nutritional Counseling for GLP-1 Users Available Now
The best path on a GLP-1 journey starts with having a nutrition expert on your side. I teamed up with Ashley Legg of Legg Day Fitness to help me. We work on putting the right foods into my body, but also dealing with side effects, building muscles, balancing nutrients, and changing my relationship with food.
We had so much success that we teamed up to bring GLP-1 help to others. Her one-on-one nutrition guidance is partly why I credit having so few side effects after three months and three dose-ups on Zepbound. I know she can help you, too.
Disclaimer: This content is for informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. We are not doctors, and you should always consult a qualified healthcare provider before starting, stopping, or modifying any medication, supplement, or treatment plan.
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