Your weekly GLP‑1 injection
Semaglutide and tirzepatide. What to expect, how to take it, and when to call us.
This is the guide we give patients starting semaglutide or tirzepatide. You're welcome to read it before you're a patient. We'd rather you knew.
The short version
- Follow your prescription exactly. Not a number from a chart, a video, or a friend.
- Same day every week. Time of day and food don't matter.
- Nausea is normal early on and after each increase. It usually settles. Tell us if it doesn't.
- Severe stomach pain that goes through to your back is not normal.
- Tell any surgeon, dentist or anesthesiologist you're on this, before any procedure.
- Book your next visit before you run out, so your treatment carries on without a gap.
When to get help
- Severe stomach pain that won't let up, especially if it goes through to your back and comes with vomiting. This can mean inflammation of the pancreas.
- Pain in the upper right of your belly, fever, yellowing of the eyes or skin, or pale stools. This can be your gallbladder.
- Vomiting or diarrhea you can't keep ahead of, or you've stopped urinating normally. Getting badly dehydrated on these medications can injure your kidneys.
- A lump or swelling in your neck, a hoarse voice, or trouble swallowing.
- Sudden changes in your vision.
- Trouble breathing, swelling of the face or throat, or a spreading rash.
What you're takingWhich product you have, and what it actually does
Semaglutide and tirzepatide belong to a class of medicines called GLP‑1 receptor agonists. Tirzepatide works on a second target as well, called GIP, which is why it’s sometimes described as a dual medication.
Which product you have. These medicines come as FDA‑approved branded products, and that is the first-line option. For some patients a compounded preparation is appropriate instead. Your prescription label tells you which one you have, and your visit notes give your clinician’s reasoning.
If yours is compounded, that means a licensed compounding pharmacy prepares it for you rather than a brand manufacturer producing it at scale. Compounded medications are not FDA‑approved. That isn’t a warning so much as a fact worth knowing, and it’s a large part of why the instruction below is to follow your own label rather than anything else.
It works on appetite, not metabolism.
Why that distinction matters, and what the medication will and won't do for you More
Weight is hard to keep off, but not because your metabolism broke. When you lose weight, hunger climbs, and it climbs about three times harder than the small drop in the calories you burn. That gap is what pulls most people back. These medications work on the appetite side of it.
Most people describe food taking up less room in their head. You stop finishing things out of habit. You get full sooner and stay full longer, partly because your stomach empties more slowly.
What it won’t do is reset anything, and it won’t stand in for eating and moving in a way you can keep up. It buys you a stretch where those choices are much easier to make. What you build during that stretch is what you keep.
How to take itYour dose, where to inject, missed doses, storage
Your dose is set for you, and so is the device it comes in. Two people on the same medicine can have different strengths, different devices and different numbers on their labels. A dose you read in a chart, a video, a forum, or from a friend is not your dose.
This matters most with a compounded preparation, where the strength in your vial is made to your prescription rather than to a fixed commercial standard. But it holds either way.
If your label is unclear, or the amount doesn’t look like what you expected, stop and message us before you inject. We would much rather answer that question than fix the result.
Time of day doesn’t matter. Food doesn’t matter. Consistency does, so pick a day and set a repeating reminder.
Your belly, at least two inches away from your navel. The front or outer thigh. The back of your upper arm. Move to a different spot each week so the skin and tissue have time to recover.
Some products come as a prefilled pen you dial to your dose. Others come as a vial you draw from with a syringe. Your label and your pharmacy’s instructions tell you which you have, and the steps differ, so follow those rather than a general video.
Common to both: wash your hands, clean the injection site with alcohol, use a new needle every single time, and put it straight into a sharps container afterwards, which is the hard plastic bin made for used needles. Never reuse or share a needle.
If you’re drawing from a vial, also wipe the vial top with alcohol before you insert the needle, and check the liquid looks clear and free of particles.
That’s deliberate. Starting low is how you avoid the worst of the side effects, and your provider moves you up in steps, at a pace set by how you’re tolerating it. There’s no prize for climbing faster, and plenty of people do well without ever reaching a high dose. Every change comes from your provider and arrives on your label. Never adjust it yourself.
If you miss a dose, or you're not sure how to store it More
Missing a dose is about timing, not amount, so it doesn’t change how much you take.
The rule is close to the same for both medicines: if it’s been about four days or less since the dose you missed, take it as soon as you remember. If more time than that has passed, or your next dose is nearly due, skip the missed one and carry on with your normal schedule.
The exact window differs slightly by product, and your label has yours. If you see different numbers quoted for semaglutide and tirzepatide, that’s usually because the two labels describe the same rule from opposite ends: one counts forward from the dose you missed, the other counts backward from your next one. They work out very similarly.
Never double up to catch up.
Storage. Keep it refrigerated unless your pharmacy label says otherwise. Don’t freeze it. Don’t use it if it looks discolored or has particles floating in it.
Side effectsThe common ones, what helps, and sulfur burps
The common ones. Nausea, burping, reflux, constipation, diarrhea, tiredness, headache, and soreness where you injected. These are usually worst in the few days after you start or after a dose goes up, and they usually settle.
Six things that genuinely help with the nausea and the constipation More
- Eat smaller amounts and stop at the first sign of full, not at “done.”
- Protein first, then vegetables, then the rest.
- Go easy on greasy, fried, and very sweet food. Those sit worst.
- Drink through the day, and consider an electrolyte drink (the kind sold for sports or rehydration) if you’re behind.
- Don’t lie flat right after eating.
- For constipation: fluids, fiber, movement. Tell us if it isn’t resolving. This is fixable and you shouldn’t just live with it.
Sulfur burps, the ones that taste of rotten egg — why they happen and how to stop them More
They catch people off guard, and they are very fixable.
Food is sitting in your stomach longer than it used to, which gives gut bacteria more time to break down sulfur-containing food and produce hydrogen sulfide gas. The smell is the gas, not anything being wrong.
What actually helps:
- Cut the fat and the portion size at the meal before they start. High-fat and large meals sit longest, and that’s what gives the fermentation time to happen.
- Ease off high-sulfur foods for a few days: eggs, red meat, garlic, onion, broccoli, cauliflower, cabbage, and whey protein shakes are the usual culprits.
- Stay upright for an hour after eating, and keep drinking water through the day.
- Bismuth subsalicylate (the pink over-the-counter stomach liquid) binds sulfide gas and often settles it within a day. It can turn your tongue and stool black for a while, which looks alarming and is harmless. Check with us first if you take blood thinners or can’t have aspirin.
- If it keeps coming back at a particular dose, tell us. Holding at the dose you’re on for longer is often all it takes.
Come to us instead of the internet if it arrives alongside real pain, vomiting you can’t keep ahead of, or a fever.
Tell us if it isn’t settling. Struggling through a dose increase isn’t a sign of commitment. It’s information. Holding at a dose or slowing down is a normal part of this, and we’d rather adjust than have you quit.
You should not take this medication ifThyroid cancer history, MEN2, pregnancy — and what else to tell us
- You or a family member has had medullary thyroid carcinoma, an uncommon type of thyroid cancer that sometimes runs in families, or you have Multiple Endocrine Neoplasia syndrome type 2, an inherited condition affecting several hormone glands. Your own history counts here as much as your family’s.
- You’re pregnant, breastfeeding, or trying to become pregnant.
Tell your provider if you have a history of pancreatitis, gallbladder disease, kidney problems, or diabetic eye disease. Also tell them if you take insulin, or a diabetes tablet from the sulfonylurea group, which includes glipizide, glyburide and glimepiride.
Three things almost nobody tells youSurgery, birth control, and protecting your muscle
These medications slow how fast your stomach empties, so food can still be in there when a procedure assumes it’s empty. That raises the risk of stomach contents getting into your lungs while you’re sedated. Say it out loud when you book and again on the day. Don’t assume it’s in your chart.
Current guidance is that most people carry on with their GLP‑1 before a planned procedure. You may be asked to stick to clear liquids for the 24 hours beforehand, particularly if you’ve been having nausea or vomiting. Let the procedure team make that call. Don’t stop your medication on your own, and don’t let anyone assume you’re not on one.
That comes from a 2024 joint statement by the American Society of Anesthesiologists, the American Gastroenterological Association, the American Society for Metabolic and Bariatric Surgery, the International Society of Perioperative Care of Patients with Obesity, and the Society of American Gastrointestinal and Endoscopic Surgeons. It replaced earlier 2023 advice to hold the weekly dose, which is still what a lot of people and a lot of printed material will tell you. If your procedure team quotes the older rule, it’s worth mentioning the update.
This is about contraceptive pills you swallow, not about any weight-loss medication. Tirzepatide can reduce how much of the hormone your body absorbs, most strongly right after you start and right after every dose increase.
So for 4 weeks after you start, and for 4 weeks after each dose increase, either add a barrier method such as condoms, or ask your provider about switching to a method that doesn’t rely on absorption from your stomach: the patch, the ring, the injection, an implant, or an IUD.
Some of what you lose on these medications is muscle, and that’s the part you don’t want back later as fat. Protein at every meal, and some form of resistance training, meaning anything that makes your muscles work against a load: weights, resistance bands, or your own bodyweight. Twice a week counts. Of everything you can do alongside the medication, this returns the most.
Two smaller ones. Many people find alcohol hits harder and appeals less. And if your stomach empties more slowly, other tablets may absorb differently, so mention it to any prescriber who’s adjusting a dose.
If and when you stopWhat comes back, and what goes first
Appetite comes back, and the health improvements fade faster than the weight does More
Appetite returning isn’t failure, and it isn’t the medication having not worked. It’s the same appetite pressure that was always there, no longer being opposed.
Here’s something most companies in this business won’t tell you. Weight tends to return gradually, over months. The health improvements go sooner, and they go further. Blood pressure, blood sugar and cholesterol drift back toward where they started well before the weight does, so you can still be well below your starting weight and have already lost most of what the medication was doing for your heart and your metabolism.
That’s the part worth talking through with your provider before you stop, rather than discovering it at your next set of blood tests.
Follow-ups and refillsBooking, and messaging us between visits
Book your next visit before you run out. It keeps your treatment continuous and lets your provider adjust things when it suits you, rather than working around a gap.
If there is a longer break, your provider may restart you at a lower dose and build back up. That’s a normal precaution to keep side effects manageable, not a penalty and not a setback.
Between visits, message us. You don’t need to wait for an appointment to ask a question, report a side effect, or tell us something isn’t working.
Where this comes fromOur sources, in plain language
- How to take it, side effects, missed doses and the contraception interaction: the FDA-approved prescribing information for semaglutide and tirzepatide.
- Surgery and procedures: the 2024 joint statement from the American Society of Anesthesiologists, American Gastroenterological Association, American Society for Metabolic and Bariatric Surgery, International Society of Perioperative Care of Patients with Obesity, and Society of American Gastrointestinal and Endoscopic Surgeons.
- Why appetite rather than metabolism: research measuring how hunger and energy expenditure change after weight loss, which finds the rise in appetite is roughly three times larger than the fall in calories burned (Polidori and Hall, Obesity, 2016).
- What happens after stopping: the extension studies that followed people after they came off semaglutide and tirzepatide (STEP 1 extension; SURMOUNT-4).
Ask us for the full references any time. We’d rather show our work than have you take our word for it.