Saxenda vs. Zepbound: 5 Differences Between These Weight-Loss Injections
Key takeaways:
Saxenda (liraglutide) and Zepbound (tirzepatide) are two FDA-approved weight-loss injections. Both are approved for use in adults, but Saxenda is also approved for certain adolescents age 12 and older.
Zepbound is available as a prefilled pen or a single-dose vial that should be injected once a week. Saxenda is available as a multiple-dose pen that you should inject once a day.
Zepbound and Saxenda have similar effects on your body, so they shouldn’t be used together. Your prescriber can recommend next steps to take if one isn’t working well enough for you.
Table of contents
Saxenda (liraglutide) and Zepbound (tirzepatide) are two injectable weight-loss medications. Saxenda was the first glucagon-like peptide-1 receptor (GLP-1) agonist to be FDA approved for weight loss in adults and adolescents age 12 and older. Zepbound was the first in its class to be approved for weight loss in adults. It’s a dual glucose-dependent insulinotropic polypeptide (GIP)/GLP-1 receptor agonist.
With an increasing number of weight-loss medications, it’s common to wonder how they differ. Are the dosages the same? Does one cause more weight loss than the others? Here, we’ll review five differences to consider when comparing Saxenda versus Zepbound.
1. Different people are eligible for Saxenda and Zepbound
Not everyone is eligible to use Saxenda or Zepbound. Both medications are approved for chronic weight management in adults who meet the following body mass index (BMI) criteria:
BMI of at least 30, or
BMI of at least 27 and one or more weight-related conditions, such as high blood pressure, Type 2 diabetes, and obstructive sleep apnea
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Unlike Zepbound, Saxenda is also approved for use in adolescents age 12 and older who have an initial body weight of greater than 132 lbs (60 kg) and a BMI that’s equal to an adult BMI of 30.
2. Saxenda and Zepbound work in similar but different ways
Saxenda and Zepbound act like the actions of gut hormones in the body. The body releases these hormones after you eat, which help balance digestion, blood glucose (sugar), and appetite.
By acting like gut hormones, Saxenda and Zepbound do the following:
Signal your pancreas to make more insulin
Signal your liver to produce less new glucose
Slow the passage of food through your digestive tract
Target areas of the brain that regulate appetite and food cravings
Both Saxenda and Zepbound act like the gut hormone GLP-1. But Zepbound also acts like another hormone, GIP. This additional action is thought to enhance the effects listed above. And this is likely why it has a greater effect on weight loss.
Good to know: Some of these actions also make the two medications helpful in managing Type 2 diabetes. That’s why the active ingredients in Saxenda and Zepbound are approved for diabetes under different brand names. Victoza (liraglutide) is a lower-dose version of Saxenda. And Mounjaro (tirzepatide) contains the same medication as Zepbound.
3. Zepbound likely causes more weight loss than Saxenda
There are no studies directly comparing Saxenda with Zepbound for weight loss. But individual clinical trial results suggest that Zepbound likely promotes more weight loss than Saxenda.
A 72-week (16.5-month) study compared the effects of Zepbound injection with a placebo (an injection with no medication) in adults considered overweight or obese. People using the highest dose of Zepbound (15 mg) lost an average of 21% of their starting body weight. Real-world studies have reported similar weight-loss results.
A 56-week (13-month) study compared Saxenda with placebo for adults considered overweight or obese. On average, people using the recommended maintenance dose of Saxenda (3 mg) lost 8% of their initial body weight. Real-world studies of people using Saxenda found similar results.
How they work: Saxenda and Zepbound act like incretins, which are natural gut hormones in the body. Learn more about how incretin-based medications work for weight loss.
Losing weight: Medications can be a useful tool to help you lose weight. But dietary and lifestyle changes help provide the best results. Experts break down science-backed tips for weight loss that you can add to your routine.
Future weight-loss medications: Many medications are available to help people lose weight. From injections to pills, learn more about new weight-loss medications on the horizon.
4. Zepbound is injected less often than Saxenda
The dosages for Saxenda and Zepbound is one of the most obvious differences between them. Saxenda is a once-daily injection. Zepbound is a once-weekly injection. This distinction may be a factor in deciding which one is right for you.
Zepbound stays in your body longer than Saxenda. It has a half-life of 5 days. Saxenda’s half-life is much shorter than Zepbound’s: about 13 hours. A medication’s half-life is the time it takes for your body to clear half of the medication. It helps researchers determine how much time should be between doses.
This difference in half-life is why you inject Zepbound only once a week but need to inject Saxenda once a day.
5. Zepbound comes as single-use pens and vials, while Saxenda is a multiple-dose pen
Zepbound is available as single-use, prefilled pens and single-dose vials that contain 0.5 mL of liquid (enough for one dose). The pens and vials come in six doses:
2.5 mg
5 mg
7.5 mg
10 mg
12.5 mg
15 mg
Zepbound pens come ready to use, with a needle preattached. But you’ll need to purchase syringes and needles separately if you’re using the single-dose vials.
Saxenda’s prefilled pens contain 3 mL of liquid and are designed for multiple doses. Each pen can deliver five different doses:
0.6 mg
1.2 mg
1.8 mg
2.4 mg
3 mg
You’ll need to purchase pen needles separately in order to use Saxenda pens. Unlike Zepbound, the needles aren’t already attached. You should use a fresh pen needle for each dose. Saxenda doesn’t come in single- or multiple-use vials.
Can you use both Saxenda and Zepbound?
No, you shouldn’t use both Saxenda and Zepbound. These medications work similarly, so using them together can increase your risk of side effects, such as nausea, constipation, and vomiting.
Using these medications together can also raise your risk of more serious side effects, such as low blood glucose (hypoglycemia). This is especially true if you also take certain diabetes medications, such as insulin.
How to save on Saxenda and Zepbound
Saxenda and Zepbound are both available as brand-name medications. There are ways to save on your prescription, such as manufacturer copay savings cards and GoodRx coupons.
If you’re eligible, you could pay as little as $25 for Zepbound per prescription with a copay savings card. GoodRx can help you save over 20% off the average retail price of Saxenda.
If cost is preventing you from accessing either medication, tell your prescriber. There are alternatives available for both Saxenda and Zepbound. Many of these are available as lower-cost generics or have cost-savings opportunities.
The bottom line
Saxenda (liraglutide) and Zepbound (tirzepatide) are injectable weight-loss medications. They are similar in many ways, but they have a number of notable differences. These include who they’re FDA approved for, how often you use them, and the injection devices they come in. You shouldn’t use Saxenda and Zepbound together since this can raise the risk of side effects. Speak with a healthcare professional to determine which one may be better for you.
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References
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