common questions
Retatrutide: Your Questions Answered From the Trials
Here are direct answers about trial amounts, weekly shots, side effects, FDA status, storage, and when this drug might become available.
How to reconstitute retatrutide?
There's no approved way to mix the powder. In trials, Eli Lilly supplied retatrutide ready for a shot. Strict drug-making rules kept it clean and made each amount the same. People in the trials didn't prepare it. No approved recipe or mixing liquid exists for powder sold outside trials. Those directions come from users or sellers, not an approved drug label. You can't tell from a gray-market label whether the powder holds the right drug or strength.
How to take retatrutide?
In Phase 2 trials, people received one shot each week. The needle went into fat just under the skin. No other way was tested in people. Trial staff began with less and raised the amount on set dates. They hoped this would ease stomach problems. Retatrutide isn't approved, so the trial method doesn't give you directions for using it elsewhere.
How much retatrutide per week?
Phase 2 tested 1, 4, 8, and 12 mg each week in people with obesity [1]. A second test used amounts from 0.5–12 mg in people with type 2 diabetes [2]. These groups gave us the reports on weight and health problems. At 12 mg, average weight fell the most: 24.2% after 48 weeks. That group also had the most people leave because of health problems, at 18% [1]. These facts aren't directions for you.
How to mix retatrutide with bacteriostatic water?
No approved mixing recipe exists. Trial teams used retatrutide that was already ready for a shot. People in those trials didn't add bacteriostatic water. That is germ-free water with an added liquid that slows germ growth. Online directions for mixing gray-market powder don't come from an approved drug label. You can't know whether the powder holds the right drug, the right strength, or harmful dirt.
How often do you take retatrutide?
Every trial so far has used one shot under the skin each week [1][2][4]. Half the drug took about 6 days to leave the blood. Enough remained seven days after a shot for the weekly trial plan. No trial in people tells you what daily or twice-weekly shots would do.
How to store retatrutide?
There are no approved storage rules for material sold outside a trial. Eli Lilly kept the trial drug within strict cold limits. Sellers once gave figures of 20 below zero before mixing and 2–8 degrees on the celsius scale afterward. In plain terms, that means a deep freezer, then a refrigerator. Those are seller claims, not approved directions. Cold storage can't prove a vial holds the right drug or strength.
How is Retatrutide administered?
People received one shot under the skin each week. All Phase 1b and Phase 2 trials in people used that way [1][2][4]. Your doctor may call it a shot under the skin. The needle goes into fat, often on the belly, thigh, or upper arm. No trial in people has tested a pill, a vein, or another way.
What is the Retatrutide dosage schedule?
In the Phase 2 obesity trial, separate groups worked toward 1, 4, 8, or 12 mg each week. Their amounts rose over the first few weeks [1]. In the Phase 2 diabetes trial, staff moved from 0.5 mg to 12 mg in steps [2]. Phase 1b also moved from 0.5 mg to 12 mg over 12 weeks [4]. The slow rise aimed to ease stomach trouble. These different plans don't give you one starting amount.
Does more retatrutide bring more nausea and stomach trouble?
Yes. Phase 2 found a clear rise. Nausea affected about 23% at 1 mg and about 45% at 12 mg. Vomiting, diarrhea, and constipation also rose with the amount. Stomach problems made 3% leave at 1 mg and 18% leave at 12 mg [1]. Reviews found that moving up slowly can help your stomach bear drugs that copy 1 hunger message [7].
Did more retatrutide lead to more weight loss?
Yes. At 48 weeks in Phase 2, the 1 mg group lost 8.7%. The 4 mg group lost 17.3%, the 8 mg group lost 22.8%, and the 12 mg group lost 24.2%. The placebo group, given shots with no drug, lost 2.1% [1]. Weight fell more as the test amount rose. Still, the added loss from 8 mg to 12 mg was smaller than at earlier steps. Group averages can't predict your weight change.
Did retatrutide harm bones or kidneys at higher amounts?
Phase 2 did not find more broken bones. Kidney health wasn't a main question in Phase 2. A blood test of how well the kidneys clean blood showed no clear warning. A Phase 3 kidney trial and a heart trial are now checking kidney health [9]. A 2025 review said drugs that copy 1 hunger message may help protect kidneys in people with diabetes [11]. We don't fully know how. Firm answers for retatrutide must wait for Phase 3. For your kidneys, no clear harm appeared early, but the larger work isn't done.
Did Phase 2 raise retatrutide from 2 mg to 12 mg?
The Phase 2 obesity report writes its four separate groups as 1/4/8/12 mg. Those slashes mean separate amounts, not fractions or steps. Staff didn't move each person from two to twelve milligrams, so the report can't answer that exact question [1]. The Phase 2 diabetes trial did raise amounts in steps [2]. Across the trials, higher amounts brought more weight loss and more stomach trouble. Slow increases helped people stay. Phase 1b moved from 0.5 to 12 mg over 12 weeks [4]. That doesn't set an amount for you.
What does retatrutide do?
Retatrutide copies three hormone messages in the body. One curbs hunger and slows food leaving your stomach. Another helps release insulin and affects stored fat. The third can raise fuel use and help the liver break down fat. In Phase 2, the 12 mg group lost 24.2% of its weight on average after 48 weeks [1]. A 2025 review called that a large change for this drug family [6].
What happens in your body after retatrutide?
Scientists made retatrutide from many small pieces found in protein. Powerful lab pictures showed the drug joining three body message sites [3]. It has 1 link tied to hunger and 1 tied to insulin. Another link copies glucagon, a hormone that helps the liver use stored fuel. Together, those actions may explain the large weight loss. Lab pictures can't tell what will happen to one person.
Is retatrutide FDA approved?
No. Retatrutide has no FDA approval. It remains an investigational drug. Your doctor can't prescribe it, and you can't get a lawful drug supply outside a trial. Semaglutide and tirzepatide have FDA-approved drug products; compounded versions do not share that approval. Retatrutide is at an earlier stage.
When will retatrutide be available?
There is no confirmed date for retatrutide to become an approved medicine. Retatrutide remains investigational. Any move to routine patient use would require FDA review and approval. A review's length cannot be inferred from a trial end date. No launch year can be promised. A trial schedule cannot settle when a medicine will be approved. Even completed trials do not guarantee approval. ClinicalTrials.gov publishes trial schedules and recruitment records, rather than approval dates.
How long does retatrutide take to work?
People in the higher-amount Phase 2 groups had clear weight loss by 12 weeks. Their weight kept falling through week 48 [1]. In Phase 1b, the top group lost more weight than the placebo group over 12 weeks [4]. A placebo group gets shots with no drug. A 2025 review said weight loss grew as the trial went on [6]. These dates come from people watched by trial staff. They can't tell what untested powder would do.
Is retatrutide better than tirzepatide?
Retatrutide brought greater weight loss in its Phase 2 trial than tirzepatide brought in a different trial. That doesn't tell you which drug is better. A Phase 3 trial is now testing the two drugs against each other [9]. That Phase 3 contest uses the same people and rules. Until Phase 3 reports, any claim that one is better rests on different people, lengths, and goals. A 2025 review said retatrutide might come near weight loss after bariatric surgery. The review called that idea early [8].
How to switch from tirzepatide to retatrutide?
There are no published medical directions for a switch. Retatrutide isn't approved, so your doctor can't prescribe it for you. The trial drug has no approved prescription-switch plan. No approved retatrutide label supplies switching instructions. Moving from tirzepatide to gray-market retatrutide puts the change outside a doctor's care and outside an approved plan.
Is retatrutide a GLP-3?
No. GLP-3 is a made-up name. GLP-1 is a body message that curbs hunger. GLP-2 is a different message that helps the gut. Retatrutide copies GLP-1 but not GLP-2 [3]. People may see GLP-1 beside GLP-2 and invent GLP-3. The real third message here is glucagon, a hormone that helps the liver use stored fuel.
Is retatrutide available?
Not as an approved drug. Retatrutide is still in Phase 3 trials. You may be able to join a trial listed on ClinicalTrials.gov if you meet its rules. The only other material is gray-market powder marked for research. No health agency or trial doctor checks that powder [1][4]. There is no approved prescription path.
What is retatrutide used for?
Trials have studied retatrutide in people with obesity, type 2 diabetes, and fatty liver. Phase 3 trials also look at the heart and kidneys. Another obesity trial compares the drug with an approved one. A 2025 review discussed possible help with weight, blood sugar, heart health, and liver fat [9]. Those hopes don't give the drug an approved use. The trials are still testing them.