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Obesity continues to be a growing concern due to the serious impacts it has on a person’s overall health and quality of life. It’s associated with medical conditions like diabetes, heart disease, and stroke, all of which are leading causes of death in the United States (Ahmad, 2020).
Some people can reverse weight gain through a healthy diet and increased physical activity. Others might need medical help to take excess weight off. If lifestyle interventions aren’t enough, one option for weight loss are medications called GLP-1 receptor agonists. Initially used to treat diabetes, GLP-1s had a noticeable side effect: weight loss.
Now two of these medications––Saxenda and Wegovy––have been explicitly approved for treating obesity.
What are GLP-1 drugs?
Glucagon-like peptide-1 receptor agonists (or GLP-1 receptor agonists for a slightly shorter version) are medications that mimic the action of a hormone in your body called glucagon-like peptide-1––thus the name.
This hormone stimulates the body to increase insulin secretion, which lowers blood sugar levels. It also slows down gastric emptying, which is when food moves from the stomach to the next stage of the digestion process. This makes you feel full for longer, reducing food intake and potentially leading to weight loss (Dungan, 2022).
Most GLP-1 medications are used to treat type 2 diabetes, but two are approved to help with weight management. These include Saxenda (liraglutide) and Wegovy (semaglutide; see Important Safety Information), which are injectable medications that require a prescription. At this time, only brand-name versions of the drugs are available (Novo Nordisk, 2021-a; Novo Nordisk, 2021-b).
Saxenda and Wegovy uses
Both these GLP-1 drugs are approved by the U.S. Food and Drug Administration (FDA) to help with weight loss. For it to be most effective, your medication regimen should be combined with a reduced-calorie diet and increased physical activity.
Saxenda and Wegovy can be used for adults with obesity––which means having a body mass index (BMI) of 30 kg/m2 or greater. They can also be prescribed for individuals with overweight (BMI of 27 kg/m2 or more) who also have a weight-related medical condition, such as high blood pressure, type 2 diabetes, and high cholesterol (Novo Nordisk, 2021-a; Novo Nordisk, 2021-b).
Saxenda is also approved to treat obesity in children ages 12 and older. To qualify, children must weigh at least 60 kg (132 pounds) and have a starting BMI of 30 kg/m2 or greater. Researchers don’t yet know if it’s safe for children with type 2 diabetes to take Saxenda (Novo Nordisk, 2021-a).
Side effects of GLP-1 drugs
All medications have a risk of some side effects. Most of the time these can be managed with help from your healthcare provider. The most commonly reported side effects from GLP-1 weight reduction medications are:
- Abdominal pain
- Low blood sugar (hypoglycemia)
Serious adverse reactions don’t happen as often, but ones to watch out for include:
- Allergic reactions
- Thyroid tumors
- Acute pancreatitis
- Gallbladder disease
- Low blood sugar (if you also take other medicines that lower blood sugar)
- Increased heart rate
- Kidney problems
- Suicidal thoughts or actions
Medical researchers don’t yet know the effects of taking GLP-1 receptor agonists like Saxenda or Wegovy during pregnancy or while breastfeeding.
Also, intentionally losing weight while pregnant isn’t typically recommended and could hurt the developing fetus. Tell your healthcare provider right away if you become pregnant while taking a GLP-1 drug (Novo Nordisk, 2021-a; Novo Nordisk, 2021-b).
Dosages and how to take
Saxenda and Wegovy are injected under the skin with a single-use pen. If you’re prescribed a GLP-1 medication for weight loss, a healthcare professional will teach you how to give yourself these injections at home. Saxenda is injected daily, while Wegovy is used weekly (Novo Nordisk, 2021-a; Novo Nordisk, 2021-b).
Wegovy comes in the following strengths (Novo Nordisk, 2021-b):
- 0.25 mg/0.5 mL
- 0.5 mg/0.5 mL
- 1 mg/0.5 mL
- 1.7 mg/0.75 mL
- 2.4 mg/0.75 mL
Your healthcare provider will start you on the lowest dose and gradually increase the amount over time to minimize side effects. You’ll stop once hitting a dose of 2.4 mg and remain on this for maintenance (Novo Nordisk, 2021-b).
Saxenda comes in doses of 0.6 mg, 1.2 mg, 1.8 mg, 2.4 mg, and 3 mg. Like Wegovy, you’ll start on the lowest dose and gradually increase it over time until you get to the maintenance amount of 3 mg (Novo Nordisk, 2021-a).
Your progress will be evaluated after being on Saxenda for 16 weeks. Most people have lost at least 4% of their body weight at this point in treatment. Clinical trials show that if you haven’t lost this much weight from your baseline by 16 weeks, Saxenda is unlikely to help you. In that case, there are other interventions for weight loss your provider can recommend (Novo Nordisk, 2021-a).
For children using Saxenda, weight loss is looked at after 12 weeks on the maximum dose. If they haven’t lost at least 1% of their body weight by then, Saxenda is unlikely to have an effect and should be stopped (Novo Nordisk, 2021-a).
Drug interactions and warnings
You shouldn’t take GLP-1 weight loss medications if you’re allergic to Saxenda or Wegovy.
Both drugs carry a boxed warning from the FDA about the risk of causing thyroid tumors. In studies on rats, GLP-1 drugs sometimes caused thyroid tumors although researchers don’t yet know how much of a risk this presents for humans.
You shouldn’t take Saxenda, Wegovy, or any other GLP-1 medications if you have a history of medullary thyroid carcinoma (MTC). You also shouldn’t use it if you or a family member have had a condition called multiple endocrine neoplasia type 2.
Warning signs of a possible thyroid tumor include (Novo Nordisk, 2021-a; Novo Nordisk, 2021-b):
- A lump on your neck
- Trouble swallowing
- Trouble breathing
- Hoarse voice
Call your healthcare provider if you experience any of these symptoms while taking a GLP-1 medicine for weight loss (Novo Nordisk, 2021-a; Novo Nordisk, 2021-b).
Saxenda and Wegovy should not be taken at the same time. Additionally, neither drug has been tested for safety and effectiveness in combination with other obesity medications or herbal supplements.
GLP-1s slow down the time it takes for food to leave your stomach. This can affect how your body absorbs other medicines you take by mouth and increase the risk of adverse effects (Novo Nordisk, 2021-a; Novo Nordisk, 2021-b).
If you’re taking a GLP-1 weight loss drug, make sure you tell your healthcare provider about any other medications or supplements that you’re taking. They may have to monitor you more often or change your dosage.
If you have any medical questions or concerns, please talk to your healthcare provider. The articles on Health Guide are underpinned by peer-reviewed research and information drawn from medical societies and governmental agencies. However, they are not a substitute for professional medical advice, diagnosis, or treatment.
- Dungan, K. & DeSantis, A. (2022). Glucagon-like peptide 1 receptor agonists for the treatment of type 2 diabetes mellitus. UpToDate. Retrieved from https://www.uptodate.com/contents/glucagon-like-peptide-1-receptor-agonists-for-the-treatment-of-type-2-diabetes-mellitus
- Novo Nordisk. (2021-a). Saxenda® (liraglutide) injection 3 mg. novoMEDLINK. Retrieved from https://www.novomedlink.com/obesity/products/treatments/saxenda.html
- Novo Nordisk. (2021-b). Wegovy™ (semaglutide) injection 2.4 mg. novoMEDLINK. Retrieved from https://www.novomedlink.com/obesity/products/treatments/wegovy.html
Dr. Steve Silvestro is a board-certified pediatrician and Senior Manager, Medical Content & Education at Ro.