Does Zepbound (tirzepatide) make you tired?

Short answer: it can. In the two placebo-controlled trials summarized in the Zepbound label, fatigue was reported by 5% to 7% of people on tirzepatide, depending on dose, against 3% on placebo.^[1] Mounjaro is the same drug. Tiredness tends to cluster around dose increases, and on low-appetite days it often tracks how little food and fluid are going in.

This page is about tirzepatide specifically: what its labels record, when in the dosing schedule tiredness shows up, and a checklist for the intake side. The general causes of tiredness across all GLP-1 medications are in why a GLP-1 can make you tired, and the food side in full is in our guide to what to eat when you're eating less.

How common is tiredness on Zepbound?

The Zepbound prescribing information pools two 72-week trials in 2,519 adults treated with the drug and lists every reaction reported in at least 2% of them and more often than on placebo.^[1] "Fatigue" in that table is a grouping: it includes asthenia (weakness), fatigue, lethargy and malaise. Three rows are relevant to feeling run down.

Reported in the trials	Placebo	5 mg	10 mg	15 mg
Fatigue (incl. weakness, lethargy, malaise)	3%	5%	6%	7%
Dizziness	2%	4%	5%	4%
Low blood pressure (incl. on standing)	0%	1%	1%	2%

From Table 1 of the Zepbound prescribing information.^[1] Two things stand out. Tiredness is more common than on placebo and rises a little with dose, but more than nine in ten people on the top dose did not report it. And the label itself warns that rates from one drug's trials cannot be compared directly with another drug's.

Does Mounjaro make you tired too?

Mounjaro and Zepbound both contain tirzepatide. Mounjaro is labeled for type 2 diabetes and Zepbound for weight management and related conditions, so their trials enrolled different people.

• In Mounjaro's pooled placebo-controlled diabetes trials, fatigue did not reach the label's 5% threshold for its main table.^[2]
• In a cardiovascular outcomes trial of 6,647 adults with type 2 diabetes and heart disease, fatigue was reported by 10% of people on Mounjaro.^[2] That trial compared Mounjaro with another diabetes medicine, not with placebo, and ran for years, so the figure is not a like-for-like comparison.
• Decreased appetite was reported by 5%, 10% and 11% of people on Mounjaro 5, 10 and 15 mg, against 1% on placebo.^[2]

That last line matters more than it looks. A smaller appetite is the point of the medication, and it is also the most common route to feeling flat.

Why does tirzepatide make some people tired?

The labels do not give a mechanism for the fatigue figures. The likely contributors are ordinary ones, and several of them are about intake.

• Much less food. A 2025 joint advisory from four US medical and nutrition societies reports calorie intake falling by 16% to 39% on these medications.^[3] It notes that vitamin and mineral shortfalls become more likely below about 1,200 calories a day for women and 1,800 for men, and lists "fatigue beyond expected levels" among the signs of a true deficiency.^[3]
• Less fluid. Less food means less of the water that comes with it, and these medications reduce drinking as well as eating.^[4][5] If stomach upset leads to vomiting or diarrhea, the Zepbound label warns that the fluid loss can lead to dehydration and, in some reported cases, kidney injury, and it advises patients to take precautions to avoid fluid depletion.^[1] More on that in GLP-1s and dehydration.
• Lower blood pressure. In the Zepbound trials, low blood pressure was reported by 1.6% of people on the drug against 0.1% on placebo, and more often in people also taking blood pressure medication.^[1] Feeling lightheaded on standing is worth mentioning to your prescriber.
• Low blood sugar, mainly with diabetes medicines. In a trial of people with type 2 diabetes, a glucose below 54 mg/dL was recorded in 4.2% on Zepbound against 1.3% on placebo, and in 10.3% of those also taking a sulfonylurea.^[1] Shakiness, sweating and sudden tiredness that ease after eating are the pattern to report.

When in the dosing schedule is tiredness most likely?

Tirzepatide is started at 2.5 mg once a week for four weeks, then raised in 2.5 mg steps, each after at least four weeks on the current dose.^[1] The label says the escalation is there to lower the risk of gastrointestinal reactions, and that most stomach upset, vomiting and diarrhea events happened during dose escalation and decreased over time.^[1] The labels do not break fatigue down by week, but in practice the same pattern is what many people describe: a harder week or two after each step, then a settling.

The advisory notes that in the trials people were allowed to stay on a dose for up to eight weeks before moving up.^[3] How fast to go is a conversation for your prescriber, not something to adjust yourself.

What should a low-appetite day include?

When appetite drops after a dose, the day can shrink to a coffee and a few bites without anyone deciding it should. A checklist makes the shortfall visible before it turns into a week of it. None of these numbers is specific to tirzepatide; they are the general reference figures, scaled for a smaller day.

Check	A working figure	Easy ways in on a small appetite
Ate within a couple of hours of waking	A small breakfast, then something every 3–4 hours[3]	Half a pot of Greek yogurt, an egg, a slice of toast
Protein at each eating occasion	RDA 0.8 g per kg of body weight; the advisory mentions 80–120 g a day as one practical target[3]	Eat the protein first. A large egg has about 6 g; 150 g of plain Greek yogurt about 14 g[6]
Fluid steadily through the day	See how much water to drink on a GLP-1	A glass beside you, sips between bites; milk, tea and broth count
Some fiber	14 g per 1,000 calories, about 20 g at 1,400[7]	A pear, a spoon of chia, half a cup of lentils
No long gap	The advisory lists long periods without meals among the habits to limit[3]	Set a reminder; the advisory suggests one if appetite does not prompt you[3]
Moved a little	Short walks; strength work on the days you can	Ten minutes after a meal
Noted energy, food and fluid	A few days is usually enough to see a pattern	A line in your phone's notes; bring it to your next appointment

Protein is usually the item that slips furthest, because protein foods are filling. The numbers and the arithmetic are in how much protein to eat on a GLP-1, and a full tirzepatide day of eating is in what to eat on Zepbound.

For transparency about our own product: Zornava Replenish is a lemon-lime drink mix with electrolytes, several B vitamins and a prebiotic fiber, made for lighter appetite days. It is one way to put fluid and some micronutrients into a day when food is short. It is not a treatment for medication-related tiredness, and it contains no caffeine or stimulants.

How long does tirzepatide tiredness last?

No trial answers this directly. What the label does say is that most stomach upset happened during dose escalation and decreased over time,^[1] and if tiredness is coming from eating and drinking too little, it should ease as intake recovers. Tiredness that does not settle within a few weeks at a steady dose, or that starts long after the dose stopped changing, is pointing at something else, and blood work is the usual way to find it.

Is Zepbound tiredness different from Wegovy tiredness?

The advisory's summary of the main obesity trials lists fatigue in 7% on tirzepatide 15 mg against 3% on placebo, and in 11% on semaglutide 2.4 mg against 5% on placebo.^[3] Those come from different trials with different people, so they are not a head-to-head comparison. The semaglutide side is covered in does Wegovy make you tired?

When should you call your prescriber?

• Tiredness that stops normal activities, or lasts beyond the first few weeks at a steady dose.
• Dizziness or fainting, especially on standing.
• Very little or very dark urine, or you cannot keep fluids down.
• Shakiness, sweating or confusion that eases after eating, particularly if you take insulin or a sulfonylurea.
• You have eaten very little for several days in a row.

Your prescriber can review the dose and the pace of increases, check other medications, order blood work and refer you to a registered dietitian.

Not sure which part of your intake is slipping on lighter days? Our two-minute quiz sorts it into water, protein, fiber and vitamins.