GLP-1 side effects: What they are and what to consider

Anyone managing type 2 diabetes or fighting to lose weight has probably heard about glucagon-like peptide-1 (GLP-1) medications. For some people, these medications have been a game changer.

These medications can help reduce appetite and help people feel fuller for longer, which can support weight loss efforts. For people with type 2 diabetes, GLP-1 treatments help control blood sugar.

But as promising as these treatments are, they're not without potential side effects. This guide helps patients understand side effects that may occur while taking these medications. 

However, it is important to first talk with a health care provider before starting or stopping any therapy, including over-the-counter (OTC) products and other side-effect management techniques. The provider can give personalized recommendations that can help lend support during a GLP-1 journey.

In this article:

What are GLP-1 medications?

GLP-1 medications can be used for weight loss and diabetes. They were first made to treat type 2 diabetes and have been prescribed by health care providers for about 20 years.

They work by copying a natural hormone that helps control hunger and blood sugar. GLP-1 medications stimulate the body to produce more insulin. Insulin lowers blood sugar and helps keep blood sugar levels within a safer, more stable range. 

These medications also lower the amount of glucagon in the blood. Glucagon is a hormone that raises blood sugar. By reducing glucagon, GLP-1 medications help prevent blood sugar spikes.

Recently, certain GLP-1 medications have been approved to help people lose weight. They do this by making people feel less hungry and by slowing down how fast the stomach empties. As a result, people feel a greater sense of fullness and less of an urge to overeat. 

However, not every GLP-1 medication is indicated for weight loss, so it’s crucial to speak with a health care provider about a person’s medical history when discussing goals and options.

Some common GLP-1 medications people might have heard of:

• Ozempic (semaglutide)
• Wegovy (semaglutide)
• Mounjaro (tirzepatide - GIP/GLP-1 receptor agonist)
• Zepbound (tirzepatide - GIP/GLP-1 receptor agonist)
• Saxenda (liraglutide)
• Trulicity (dulaglutide)

Long-term side effects of these medications aren't well-studied yet.

Before starting any new medication, people should always check with their primary care provider or another trusted health care provider.

A health care provider can help with weight loss. The MinuteClinic Weight-Loss Program, for example, offers support and personalized plans to assist people on their weight-loss journey.

Most common GLP-1 side effects

GLP-1 medications can cause digestive issues, whether someone is taking them for diabetes or weight loss.

• Common side effects may include:
• Constipation 
• Diarrhea
• Nausea
• Vomiting

These problems are more likely to show up when people first start treatment or after a recent increase in dosage. In fact, higher doses of GLP-1 medications are more likely to cause side effects. Be sure to check with a health care provider if experiencing side effects that are severe, prolonged or unexpected.

Possible but less common GLP-1 side effects

Some people experience less frequent but still significant side effects with certain GLP-1 medications, such as:

• Diabetic eye problems (diabetic retinopathy): Certain GLP-1s can worsen existing retinopathy in people with diabetes.
• Dizziness: Feeling faint or as if the room is spinning.
• Fatigue: Feeling extremely tired or low on energy, which can make everyday tasks more difficult.
• Headache: Pain in any part of the head.
• Indigestion: Bloating, burping and burning or being uncomfortable in the upper stomach; feeling full too quickly or overly full after eating.
• Injection site reactions: Itching, redness, swelling or other irritation at site where the GLP-1 was injected.
• Loss of appetite: Little or no desire to eat.
• Suicidal behavior and ideation: In serious but infrequent cases, some individuals taking certain GLP-1s can experience suicidal thoughts or mood changes.

Potential side effects can vary by product, so always speak to a health care provider with any questions.

Rare GLP-1 side effects

• Bile duct obstruction: A blockage in the bile duct that stops bile flowing from the liver to the small intestine.
• Bowel obstruction: A blockage in the intestines that prevents the normal passage of food and liquids.
• Gallstones (gallbladder disease): Hard pieces of cholesterol form in the gallbladder.
• Gastroparesis: Food moves too slowly (or not at all) from the stomach to the small intestine.
• Increases in heart rate: A small rise in resting heart rate (usually one to four beats per minute) can happen, although actual changes vary by age and medication.
• Low blood sugar (hypoglycemia): This medicine can intermittently cause low blood sugar, especially if taken with insulin or a class of medications called sulfonylureas.
• Pancreatitis: Inflammation of the pancreas, often accompanied by severe abdominal pain.

Potential side effects can vary by product, so always speak to a health care provider with any questions.

Side effects reported after GLP-1 medications were already on the market

Some additional side effects surfaced after the U.S. Food and Drug Administration (FDA) approved GLP-1 medications.

• Pulmonary aspiration during anesthesia or deep sedation: Food or liquid accidentally enters the lungs while a person is under anesthesia or very deeply sedated.
• Serious allergic reactions (hypersensitivity reaction): Potentially life-threatening. Symptoms include swelling beneath the skin and itchy bumps (hives).
• Serious kidney problems (acute kidney injury): Sudden kidney failure or worsening of existing kidney conditions.

Potential side effects can vary by product, so always speak to a health care provider with any questions.

Why do GLP-1s have warnings about thyroid C-cell tumors?

GLP-1 medications include boxed warnings, also known as black box warnings. These are the most serious safety warnings that the FDA can give to medications. These warnings are meant to alert consumers to the major risks of the medication.

The reason GLP-1 medications have these warnings is because animal studies found a connection between these medications and thyroid tumors. But so far, there’s no direct evidence that these tumors will appear in humans.

How to help manage common GLP-1 side effects

Always speak to a health care provider before self-treating any GLP-1 side effects to rule out any more serious causes and so they can provide guidance for OTC options.

• Nausea:
  • Eat bland, low-fat foods like crackers, toast or rice.
  • Avoid fried, fatty, greasy or overly sweet foods.
  • Try smaller, more frequent meals. If someone usually eats three times a day, they can try having four or more mini meals instead.
  • Slow down eating and stop when feeling full.
  • Steer clear of strong smells and try nibbling on crackers, mints or ginger.
  • Stay hydrated with clear or ice-cold drinks.
  • Choose water-rich foods like soups or gelatin.
  • Avoid lying down right after eating.
  • Go outside for a bit of fresh air.
• Vomiting: Stay hydrated, try eating smaller meals more often and follow the nausea tips listed above.
• Diarrhea: Stay hydrated and stop consuming dairy and high-fiber foods until things calm down.
• Constipation: Eat more fiber and drink lots of water.

What is the “Ozempic face”?

Anyone who follows celebrity gossip or weight loss stories might’ve heard about the infamous "Ozempic face." But what is it, exactly? Basically, it’s when the face starts to look hollow or sunken, which can happen when someone loses weight in their face quickly.

But the term "Ozempic face" can be a bit misleading. It can happen with any GLP-1 medication, or even just from rapid weight loss. That includes Ozempic, other medications or even a strict diet. As a result, some people might notice changes like:

• A more hollow or sunken look
• Changes in the shape or size of the lips, cheeks and chin
• More pronounced wrinkles
• Sunken eyes
• Sagging jowls around the jaw and neck

Losing weight gradually usually means these changes aren't noticeable. It's the faster weight loss that comes with GLP-1 medications that can make facial changes more obvious. If the "Ozempic face" side effects are distressing, consulting a plastic surgeon is a potential option to address this problem.

Which GLP-1 medications cause the fewest side effects?

There’s no simple answer unfortunately. In general, the gastrointestinal (GI) side effects of GLP-1 medications depend on the dose and the individual patient. In the end, there’s no one-size-fits-all when it comes to these medications. Each one has its pros and cons, which is why it is important to speak to a health care provider; they can help pick the best option based on what a patient needs.

When to seek immediate medical advice

Most GLP-1 side effects aren’t serious. However, contact a health care provider right away if experiencing any of the following:

• Difficulty swallowing or breathing
• Inability to pass gas or move bowels
• Intense pain or tenderness in the belly
• Jaundice (yellow skin or eye color)
• Mass in the neck
• Persistent hoarseness
• Severe vomiting or diarrhea

Cosmetic changes from GLP-1 medications

Medications like Wegovy and Zepbound have surged in popularity for weight loss. But with rapid weight loss can come a few unexpected changes in appearance:

• Facial volume loss (“Ozempic face”): A hollow or sagging look in the cheeks.
• Loose or excess skin: Often around the stomach, arms or other areas. This can lead to irritation or hygiene concerns.

If someone finds these physical changes worrisome or uncomfortable, they should speak with a health care provider, who can discuss their options. Options may be gradual weight-loss strategies or exercise routines to help firm the skin. In some cases, surgical or cosmetic procedures are used.

Key takeaways

GLP-1 medications help control blood sugar and aid weight loss. They can cause some side effects, like an upset stomach or diarrhea, and rarely, more serious issues like pancreatitis or thyroid problems. Anyone thinking about taking them or experiencing side effects should consult with a primary care provider or another trusted health care provider to understand the risks.

This content is for informational purposes only and is not medical advice. Consult your health care provider before taking any vitamins or supplements and prior to beginning or changing any health care practices.