If you’ve been prescribed a glucagon-like peptide-1 (GLP-1) receptor agonist like semaglutide or liraglutide, you may wonder how long it will take to start working.

One MyObesityTeam member asked, “How long does it take for GLP-1s to work? It’s my third week, but I don’t notice a difference.”

These medications have gained attention for their effectiveness in blood sugar control and weight management. However, results don’t happen overnight. Changes in blood sugar and weight follow different timelines, and noticeable results can take weeks to months.

In this article, learn about how these medications work, what to expect after your first dose, and how long it takes to notice changes in blood sugar and weight.

🗳️ Which GLP-1 medication do you take?

Liraglutide

Orforglipron

Semaglutide

Tirzepatide

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Timeline for Blood Sugar Control

GLP-1 medications start working after your first dose. However, the first dose is typically kept intentionally low to help your body adjust to the medication and reduce side effects like nausea. You may notice a smaller appetite early on, and blood sugar may also start to improve soon after treatment begins.

Your provider typically increases the dose of your GLP-1 in steps. For treating type 2 diabetes, dosages for semaglutide start at 0.25 milligrams per week and can increase to 0.5 milligrams per week after four weeks, up to a maintenance dose of 1 milligram or 2 milligrams per week with at least four weeks of dose stabilization in between.

At the same time that your provider is increasing the dose of your GLP-1, they may recommend reducing or stopping certain other blood sugar medications to lower your risk of low blood sugar.

Long-term blood sugar control is measured through hemoglobin A1c. It gives an idea of your average blood sugar levels over the past three months. In clinical trials, GLP-1s reduced A1c within the first three months of treatment, with continued improvement at six months and well-controlled levels beyond one year.

Timeline for Weight Management

Although you may notice a smaller appetite shortly after starting your medication, weight loss from GLP-1s can take longer to notice compared to blood sugar changes. In clinical trials, weight loss was observed at three months, but the most effective weight loss happened between three and six months of treatment.

Studies also found that weight loss often leveled off between six and 12 months of treatment, on average, although some people continued losing weight beyond a year on GLP-1s.

How much weight you lose and for how long depends on your medication and dose. Here’s what clinical trials have found for three GLP-1 medications:

• Liraglutide (Saxenda) — One-third of study participants without diabetes taking 3 milligrams daily lost 10 percent of their body weight. Weight loss leveled off at 20 weeks and remained steady through week 56 while they continued taking the drug.
• Semaglutide (Wegovy) — Study participants taking 2.4 milligrams per week lost 15 percent of their body weight. Weight loss leveled off at 68 weeks and remained steady through week 104.
• Tirzepatide (Zepbound) — Study participants taking 15 milligrams per week lost an average of 22.5 percent of their body weight at 72 weeks. Unlike the other medications listed, tirzepatide acts like two natural hormones, GLP-1 and glucose-dependent insulinotropic polypeptide (GIP), that help regulate blood sugar and appetite.

What Can Affect How Quickly GLP-1s Work for You?

Several factors can affect how quickly GLP-1s work for you:

• Dose — Higher doses can increase the amount and effect of the medication in your body. For example, semaglutide doses for weight management are higher than for blood sugar control.
• Body weight — Higher body weight may lower the amount of medication circulating in your bloodstream, but more studies are needed to understand this.
• How you take it — Certain medications taken by mouth, including Rybelsus and oral Wegovy, need to be taken on an empty stomach with a small amount of water, followed by a waiting period before eating, drinking, or taking other oral medicines. Food can reduce how much medication your body absorbs. However, orforglipron (Foundayo), a new FDA-approved oral GLP-1 for weight management, does not need to be taken on an empty stomach.
• Lifestyle habits — In clinical trials, participants used GLP-1s with changes in their diet and physical activity.

For best results, take your medication exactly as prescribed and let your doctor know about any side effects or concerns.

When To Talk to a Doctor

The first few weeks on a GLP-1 are mainly about helping your body adjust to the medication. Slow progress during the first month isn’t necessarily a sign the medication isn’t working.

Talk to your doctor if:

• You’ve reached your maintenance dose and aren’t seeing changes
• Side effects, like nausea, vomiting, or diarrhea, don’t improve over time
• You have severe abdominal pain (seek medical care right away)
• You notice signs of low blood sugar, such as dizziness or weakness
• You’re having trouble following dietary or physical activity guidelines

Don’t change your dose or stop taking your GLP-1 without talking to your doctor first. If you have questions about your symptoms or progress, talk to your care team about what to do next.