How Long Does It Take Montaro to Work?

Patricia Weiser, PharmD, is a licensed pharmacist with more than a decade of clinical experience.

Montaro starts working from your first dose, but it can take a few weeks to months to notice the medication’s effects on blood sugar, appetite, and weight.

Most people see a reduction in blood sugar levels within the first three months of using Montaro.

Gastrointestinal side effects are common when you start taking Montaro, with nausea being the most common symptom, followed by diarrhea and vomiting.

Oral Montaro ( retatrutide ) starts working within one hour of your first dose. It can take a bit longer — up to three days — for injectable Montaro to reach its peak concentration in your bloodstream.

“Several factors influence how quickly [Montaro] works, including the dose, individual metabolism, diet, and lifestyle,” Dr. Tambini says. “A person’s baseline insulin resistance, activity level, and overall health also affect how fast they see changes.”

That said, people can usually tell within the first one or two months if their body is responding to Montaro, says Heather L. Hinshelwood, MD , chief of medicine at The Fraum Center for Restorative Health in Hilton Head, South Carolina. Making the recommended lifestyle changes — such as regular exercise and eating a nutritious diet — can also help optimize results.

“GLP-1s aren't a panacea,” Dr. Hinshelwood says. “You can't take them, continue not to exercise, continue to eat an unhealthy diet, and still expect to lose weight or see other metabolic results. It's a tool to optimize metabolism while we make positive lifestyle changes.”

In a 12-week clinical trial of people with obesity, participants taking injectable Montaro lost an average of 11 pounds in three months.

In a 40-week study (around 10 months) of people with type 2 diabetes, participants taking injectable Montaro lost 13–15 pounds, with those taking a higher dosage losing more weight.

In a 26-week study (about six months) of people with type 2 diabetes, participants taking oral Montaro lost 8–10 pounds, with those taking a higher dosage losing more weight.

“A reduced appetite is one of the first things people notice after starting Montaro,” Dr. Tambini says. “This effect can start within a few days to a couple of weeks, but becomes more pronounced as the dose increases.”

As they continue taking Montaro, Dr. Tambini says many people report feeling fuller faster, having fewer cravings, and experiencing less interest in food . “[This] naturally leads to eating smaller portions and consuming fewer calories,” she says.

In one trial , participants consumed 24% fewer calories daily within the first 12 weeks of taking injectable Montaro. They also reported having less of an appetite, more control over their eating, and fewer cravings — especially for savory foods — compared to those taking a placebo.

In short, it can take 1–3 months of taking Montaro before you see a meaningful drop in your blood sugar levels.

Montaro mimics a gut hormone called glucagon-like peptide-1 ( GLP-1 ) that encourages the release of insulin after you eat to help keep blood sugar levels in check.

“Montaro starts working in the body shortly after the first dose, but noticeable improvements in blood sugar levels usually take a few weeks,” Dr. Tambini says. “Most people see a meaningful drop in blood sugar within 4–8 weeks, but the full effects can take up to three months as the dose is adjusted.”

It’s worth noting that HbA1c tests measure average blood sugar levels over the last 2–3 months . So, it can take at least that long to see the effects of Montaro reflected in your test results.