Key Insights
- GLP-1 medications can provide significant benefits for weight loss, diabetes management and cardiovascular health, but they may cause unwanted side effects.
- Patients should discuss treatment goals, existing health conditions and potential risks with their healthcare provider before starting a GLP-1 medication.
- Persistent gastrointestinal symptoms, significant hair loss or new vision changes should be shared with a healthcare provider for proper evaluation.
UAB experts explain common GLP-1 side effects and share strategies to reduce risks, recognize warning signs and know when to seek medical care.As more patients use GLP-1 medications for weight loss, experts at the University of Alabama at Birmingham caution they should understand the potential side effects before they begin taking this class of medications.
GLP-1s can aid with managing diabetes and lowering risk of cardiovascular disease by mimicking the natural GLP-1 hormone already found in the body. They can cause unwanted side effects including gastrointestinal symptoms, hair shedding and vision problems.
Gastrointestinal side effects
Elizabeth Terry, M.D., an assistant professor in the Division of Gastroenterology and Hepatology in UAB’s Department of Medicine, says the most common side effects she encounters among patients who take GLP-1s are early satiety, nausea, vomiting and constipation.
To minimize gastrointestinal side effects, Terry recommends starting with a low dose of medication and slowly increasing the dosage over time. Side effects may decrease in severity as an individual becomes used to the medication.
Many gastrointestinal symptoms occur because of the way GLP-1 medications affect the digestive tract.
“It slows down the movement of food through your stomach, small intestine and colon,” Terry said. “The slowing down of the stomach causes early satiety, nausea, vomiting and sulfur burps. The slowing down of the rest of the GI tract can also lead to constipation.”
Patients with preexisting gastrointestinal conditions, such as gastroparesis or chronic constipation, may have worsened symptoms when they begin taking a GLP-1. Terry says that opioids and some anti-diarrheal medications can further slow the intestines and increase side effects.
In addition to slowly increasing the dosage, patients may be able to mitigate symptoms by staying hydrated and avoiding medications that could compound gastrointestinal side effects.
Terry says because GLP-1 medications are relatively new, researchers are continuing to gather information on their long-term side effects. They can rarely cause complications such as gallstones, but most side effects are reversible once a person stops the medication. It can take weeks or months for symptoms to subside upon stopping medication usage.
“These medications can be life changing for some patients, leading to significant weight loss, improvement in health conditions and improvement in overall quality of life,” Terry said. “However, with the good can come some bad. Therefore, we are seeing more patients in clinic who have developed significant side effects from these medications.”
Hair shedding linked to weight loss
Lauren Kole, M.D., an associate professor and vice chair for Medical Education in the UAB Department of Dermatology, says hair shedding is a frequent concern among patients using GLP-1 medications. However, the medications themselves may not be directly responsible.
“It’s not due to the actual medication itself, but more the stress on the body that rapid weight loss is causing,” Kole said. “It makes our body focus less on the energy required to grow hair and the stress that’s being put on the body by that weight loss.”
The most common type of hair loss associated with GLP-1 inhibiters is called telogen effluvium, which is a temporary, stress-induced form of hair shedding.
“In most cases, it is temporary, and it can happen several months after that stressor on the body,” Kole said.
Rapid weight loss can also affect factors that may contribute to hair shedding, such as nutritional deficiencies or hormonal changes. To reduce the risk of hair shedding, Kole recommends avoiding rapid weight loss, instead losing weight in a gradual and sustained manner and maintaining proper nutrition.
Treatment options for hair loss related to taking a GLP-1 include over-the-counter products or prescription medications, such as oral minoxidil or oral antiandrogen therapies.
Kole says anytime a patient is experiencing hair loss when using a GLP-1 drug, they should visit a dermatologist for evaluation to rule out other conditions.
Vision concerns
Elizabeth Steele, O.D., a professor and associate dean for Clinical Affairs at UAB’s School of Optometry, says there may be a correlation between GLP-1 medications and eye health. Researchers are still evaluating a possible association with a vision-threatening condition known as nonarteritic ischemic optic neuritis.
While the association is unclear, the FDA recently announced a safety warning requirement for GLP-1 medication labels.
“It is important to recognize that many of the factors known to increase nonarteritic ischemic optic neuropathy, including hypertension, hyperlipidemia, diabetes, obesity and older age, are common among the same patients who are prescribed GLP-1 medications,” Steele said. “This makes it difficult to determine whether any observed clinical findings are due to the medication itself or the underlying risk profile of the population being treated.”
Steele says studies have shown that patients with diabetes should be especially mindful when beginning to take a GLP-1 drug, specifically patients whose baseline blood sugar levels were extremely high. Studies support an increased risk of diabetic retinopathy during the first months of beginning a new GLP-1 medication.
“Researchers believe this may be related to the rapid improvement in glucose control and associated metabolic changes that occur early in treatment rather than a direct toxic effect of the medication itself.”
Vision loss associated with nonarteritic ischemic optic neuritis is typically sudden, while vision loss from diabetic retinopathy is typically more gradual. Any new vision loss, blurred vision or visual disturbance is cause for a prompt evaluation from an optometrist or ophthalmologist, Steele says.
Discuss the risks and benefits
UAB experts emphasize the importance of working with a medical provider, discussing treatment goals and existing medical conditions prior to beginning a new GLP-1 medication. Patients can potentially reduce side effects by starting at a low dose, avoiding rapid weight loss, maintaining balanced nutrition, staying hydrated and participating in routine eye care. Individuals who experience persistent gastrointestinal symptoms, significant hair loss or new vision changes should speak with their physician to evaluate a cause and ensure safe usage of a GLP-1.