If you’re exploring glucagon-like peptide-1 (GLP-1) medications for weight loss, you’ve probably noticed a new option on the market. Eli Lilly’s Foundayo® (orforglipron) earned FDA approval in April 2026 as a daily pill for weight management. The company also makes Zepbound® (tirzepatide), a weekly injection approved for weight loss.

Although both belong to the same family of medications, they work a little differently. Here’s what you need to know about orforglipron versus tirzepatide before discussing these options with your provider.

What are orforglipron and tirzepatide, and how do they work?

Both orforglipron and tirzepatide are prescription drugs that belong to a category called glucagon-like peptide-1 receptor agonists (GLP-1 RAs). This means they activate the same receptors as GLP-1, a hormone your gut naturally releases. After you eat, GLP-1 tells your brain to feel full, slows how quickly food leaves your stomach, and triggers insulin release to manage blood sugar.

So what’s tirzepatide doing differently? In addition to mimicking GLP-1, this drug targets a second gut hormone called glucose-dependent insulinotropic polypeptide (GIP). GIP helps fat cells store and use energy more efficiently, meaning less fat builds up around your organs. It also regulates brain signals so you don’t feel hungry as often.

What sets orforglipron apart is its chemistry. Normally, GLP-1 RA pills have a pretty low bioavailability. This means your body has a hard time absorbing and using the medicine. Orforglipron, though, handles stomach acid better than other GLP-1 RAs. So, more of the drug can make it into your digestive system before breaking down. Studies suggest this makes orforglipron more effective at controlling blood sugar than oral semaglutide (another GLP-1 RA).

Tirzepatide and orforglipron: Side-by-side comparison

Here’s how these two medications compare:

*The orforglipron weight loss data comes from the ATTAIN-1 trial and tirzepatide’s from SURMOUNT-1. They’re separate studies, not a head-to-head comparison.

What kind of side effects are most common with these medications?

Because these medications are both GLP-1 RAs, they have similar side effects. Most reactions are digestive, mild to moderate, and ease as your body adapts to each dose increase.

Here are the most common orforglipron and tirzepatide side effects:

Boxed warnings

The FDA has flagged both medications with a boxed warning for risk of thyroid C-cell tumors. There’s an important difference in the preclinical data, though. Tirzepatide caused tumors in rats at clinically relevant doses, while orforglipron didn’t produce tumors in rodent studies. This is because orforglipron doesn’t seem to affect rats at all. But the warning still applies to both because researchers haven’t determined whether the rodent findings translate to humans.

Drug interactions to discuss with your provider

Foundayo® is processed in the liver by an enzyme called CYP3A4. Some medications, like the antifungal ketoconazole or the antibiotic clarithromycin, slow down that enzyme. Others, like the seizure medication carbamazepine, speed it up. Either way, these medicines change how much orforglipron ends up in your bloodstream. This can make it less effective or increase your risk of side effects.

CYP3A4 doesn’t process Zepbound®, so its interaction list is shorter. Insulin may need dose adjustments to avoid low blood sugar.

Both drugs slow gastric emptying, which can affect how well your body absorbs other oral medications. Because of this, medicines like warfarin might not be as effective. And if you take birth control pills, your provider may recommend switching to a non-oral method.

One hard rule applies to both: Never take orforglipron and tirzepatide—or any other two GLP-1 medications—at the same time. Researchers haven’t studied whether it’s safe to do so, and neither prescribing label recommends it.

What’s the main tradeoff between efficacy and convenience when switching treatment options?

People taking tirzepatide lose roughly twice the weight, but orforglipron costs less and doesn’t require injections. The question is which benefit matters more to you and whether that priority might shift as your goals, lifestyle, or budget change. 

Both medications offer a Lilly savings card that brings the price to $25 per month with insurance. Without insurance, the gap is meaningful. Through LillyDirect, Foundayo® runs $149–299 per month, versus $299–449 for Zepbound®. Starting in July 2026, both are expected to be available at $50 per month for eligible Medicare Part D patients.

How to choose based on goals and life stage

If you’re managing type 2 diabetes or OSA alongside weight loss, consider tirzepatide. It’s the only option of the two with FDA approval for these conditions. But if daily convenience, lower cost, or avoiding injections are higher priorities, orforglipron may be a better option.

This doesn’t have to be a permanent decision. You can start on Zepbound® and switch to Foundayo® later. Moving from a dual-hormone medication to a single-hormone one could mean some weight regain, though far less than stopping treatment entirely. In the ATTAIN-MAINTAIN trial, people who lost weight on tirzepatide and then switched to orforglipron kept about 75% of their weight loss over a year.

Maven Clinic can help you find the right fit

Only you and your provider can assess the tradeoff between tirzepatide’s weight loss edge and orforglipron’s everyday convenience. The choice depends on personal factors, like your health profile, where you are in your weight loss journey, and what matters most in your day-to-day routine.

A Maven Clinic provider can help you weigh your GLP-1 RA treatment options. We’ll help you choose a starting point and adjust your plan as your needs evolve.

FAQ

Can I switch from tirzepatide to orforglipron?

Yes. In the ATTAIN-MAINTAIN trial, people who switched from tirzepatide to daily orforglipron kept about 75% of their weight loss over 52 weeks. Some weight regain is expected when moving from a dual-hormone medication to a single-hormone one, but the transition is clinically supported.

Is orforglipron FDA-approved?

Yes, the FDA approved orforglipron on April 1, 2026 under the brand name Foundayo®. It’s authorized for chronic weight management. Adults with obesity or those who are overweight with at least one weight-related medical condition qualify. 

Can orforglipron and tirzepatide be taken together?

No. Both prescribing labels state that you shouldn’t take two GLP-1 RAs at the same time. Combining them raises the risk of severe digestive side effects with no added clinical benefit.

Is orforglipron approved for type 2 diabetes?

Not yet. As of mid-2026, Foundayo® is approved for weight management only. However, Eli Lilly has published positive trial data for orforglipron in type 2 diabetes. Based on this, they’ve announced plans to seek FDA approval for that use.

What are the maximum doses for orforglipron and tirzepatide?

Orforglipron dosage starts at 0.8 mg once daily, with gradual increases up to a maximum of 17.2 mg. Tirzepatide dosage starts at 2.5 mg once weekly, and the maximum dose is 15 mg.