Considering GLP-1 Injections for Weight Loss? Here Are 8 Things to Know Before You Start

Glucagon-like peptide-1 (GLP-1) injections such as Wegovy and Wegovy HD (semaglutide), Zepbound (tirzepatide), and Saxenda (liraglutide) can help many people lose a meaningful amount of weight. But they aren’t a quick fix, and they aren’t right for everyone.

Before starting GLP-1 injections, it’s good to understand how they work, the possible benefits, and what trade-offs come with treatment — such as side effects and cost. If you’re considering a GLP-1 injection for weight loss, here are eight key things to know before you begin.

1. GLP-1 injections work by changing appetite and digestion

GLP-1 injections — or GLP-1 receptor agonists — mimic the natural hormone GLP-1, which helps regulate appetite, fullness, and digestion. Some also mimic a second hormone, glucose-dependent insulinotropic polypeptide (GIP), for additive effects. These are called dual GIP / GLP-1 receptor agonists.

GLP-1 injections work by:

• Reducing appetite so you feel less hungry

• Helping you feel full sooner during meals

• Slowing digestion, which keeps you feeling satisfied longer

• Reducing food cravings and “food noise," making it easier to stop thinking about food between meals

Together, these effects can make it easier to eat less without constantly feeling hungry. And this helps support weight loss.

2. Not all GLP-1 injections are the same

GLP-1 injections work in similar ways for weight loss, but they’re not identical. They differ in their active ingredients and dosage schedules, as well as how much weight people typically lose. They also have different dosage form options, including single-use and multidose pens, and single-use vials.

Wegovy, Wegovy HD, and Zepbound are all injected once weekly and tend to lead to more weight loss on average. Saxenda, on the other hand, is injected once daily and generally results in more modest weight loss. Wegovy and Saxenda are approved for people ages 12 and older, while Zepbound and Wegovy HD are approved only for adults.

In addition to helping people lose weight, Wegovy is also prescribed for its cardiovascular and liver-related benefits. This can make it a good option if you have heart disease or metabolic dysfunction-associated steatohepatitis (a type of fatty liver disease), or MASH. Alternatively, Zepbound can be a good choice if you have moderate-to-severe obstructive sleep apnea, since it’s approved for this condition.

Here’s how GLP-1 injections compare:

A healthcare professional can help determine which option is the best fit based on your health history, preferences, and budget.

Good to know: You may also see compounded GLP-1 injections, such as custom microdoses, being advertised. These products are made by pharmacies and are not FDA approved. They also aren't exactly the same as Wegovy, Zepbound, or Saxenda.

3. Weight loss can be significant, but results vary

Many people lose a meaningful amount of weight with GLP-1 injections. During clinical trials, participants have lost an average of about 10% to 20% or more of their starting body weight, depending on the medication and dose.

That said, results vary from person to person. In addition to the medication and dose, factors such as treatment duration, lifestyle habits, and individual biology all play a role. Some people lose weight steadily, while others see slower or more modest changes. There are also those who don't respond at all.

Weight loss with GLP-1 injections tends to happen gradually over several months. Setting realistic expectations and focusing on long-term progress can help make treatment more sustainable.

4. Side effects are common, especially early on

Side effects are fairly common with GLP-1 injections, particularly when you start treatment or if you increase your dose. Most GLP-1 side effects are gastrointestinal (GI) and may include:

• Nausea

• Vomiting

• Diarrhea

• Constipation

• Stomach pain or bloating

These side effects are usually temporary and often improve as the body adjusts to the medication. But while GLP-1 side effects are mild and manageable for some people, they can be more severe for others. That’s why it’s best to keep in touch with your care team, so they can make adjustments if needed.

Starting with a low dose that’s increased gradually helps reduce both how severe side effects feel and how long they last. Lifestyle factors, such as your diet, fluid intake, and physical activity, can also influence how well you tolerate treatment.

While less common, serious side effects have also been linked to GLP-1s, including:

• Pancreatitis (inflammation of the pancreas)

• Gallbladder problems

• Acute kidney damage (often due to dehydration)

• Eye problems, including vision loss

• Severe gastroparesis (slowed stomach emptying)

GLP-1s also carry a boxed warning (the FDA’s strongest medication warning) for an increased risk of thyroid C-cell tumors. This is based on findings from animal studies and hasn’t been confirmed in humans.

5. GLP-1 injections are meant for long-term use

GLP-1 injections are generally intended for long-term treatment, not short-term weight loss. These medications work best when they’re used consistently over time.

Many people who stop using GLP-1 injections regain some or all of the weight they lost. Because of this, ongoing treatment may be needed to maintain results, though treatment plans can change. In some cases, your prescriber may recommend slowly tapering your dose or switching to a GLP-1 pill over time.

Before you start treatment, a healthcare professional can help you determine how long you may need to use GLP-1 injections. If you’re already using a GLP-1, your prescriber can advise whether adjustments are needed based on your progress, goals, and side effects.

6. GLP-1 injections aren't a good fit for everyone

GLP-1 injections can be effective for weight loss, but they aren’t appropriate for everyone. You may be told to avoid GLP-1 injections if you:

• Have a personal or family history of medullary thyroid cancer

• Have multiple endocrine neoplasia syndrome type 2

• Have a history of pancreatitis

• Have severe gastrointestinal issues, such as gastroparesis

• Are pregnant or breastfeeding

• Are allergic to any ingredient in the GLP-1 injection

A healthcare professional can review your medical history, current medications, and weight-loss goals to help determine whether a GLP-1 injection is safe and appropriate for you.

Quiz: Think you know how to use a GLP-1?

7. Lifestyle changes still matter

GLP-1 injections can support weight loss, but they work best when combined with healthy lifestyle habits. These medications aren’t a substitute for good nutrition, exercise, and other behaviors that support long-term health.

Focusing on balanced, protein-rich meals, staying hydrated, and being physically active can help improve results from GLP-1s and reduce side effects. Getting enough sleep and managing stress also play important roles in weight management.

Building positive, sustainable habits alongside using GLP-1 injections can help you maintain weight loss over time and support overall health.

8. There are ways to make GLP-1 injections more affordable

For some people, cost can be a barrier to starting or continuing GLP-1 injections. But there are several ways to help make these medications more affordable:

• Save with GoodRx. If you’re new to using GoodRx for Wegovy savings, you can pay an introductory price of $199 per month for the first two fills of injections (with certain doses). For future fills and other Wegovy doses, you can pay $349 (standard Wegovy) or $399 (Wegovy HD) per month. Access Zepbound KwikPen through GoodRx starting at $299 per month. Subscribers to GoodRx for Weight Loss can also access FDA-approved, brand-name GLP-1 medications.

• Save with a copay savings card. If you have commercial insurance, you could pay as little as $25 for Wegovy or $25 for Zepbound monthly supplies with a manufacturer copay savings card.

• Save with an online pharmacy service. NovoCare Pharmacy and LillyDirect can ship GLP-1 medications directly to your home at lower, self-pay prices.

• Save with a generic. Saxenda is the only GLP-1 for weight loss that’s available as a lower-cost generic. With a free GoodRx coupon, you could pay as little as $372.45 for 1 carton of generic liraglutide at certain pharmacies.

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Written by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Reviewed by:

Christina Aungst, PharmD, MWC

Christina Aungst, PharmD, MWC is a senior pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019.

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