What the labels list, and what they do not
Zepbound®’s US label builds its side-effect table from SURMOUNT-1 and SURMOUNT-2, two 72-week trials in 2,519 adults treated with Zepbound®. A reaction is included only if at least 2% on Zepbound® reported it and it was more frequent than on placebo. [1] Muscle aches, joint pain, back pain and cramps do not appear. The Canadian monograph reports the same trials with a 1% threshold and also omits them, and the EU product information for tirzepatide, sold in Europe as Mounjaro®, does the same. [3][4]
Several rows describe sensations that people may call aches, summarised below.
| Finding | Zepbound® 5 / 10 / 15 mg vs placebo | Source |
|---|---|---|
| Injection site reactions (includes pain, bruising, redness, itching, rash at the site) | 6 / 8 / 8% vs 2% | US Table 1 [1] |
| Fatigue (includes asthenia, lethargy, malaise) | 5 / 6 / 7% vs 3% | US Table 1 [1] |
| Dysesthesia (abnormal skin sensation) | 0.2 / 0.2 / 0.4% vs 0.1% | US §6.1 [1] |
| Hypersensitivity reactions, mostly skin (rash, itching) | 5 / 5 / 5% vs 3% | US Table 1 and §6.1 [1] |
| Injection site pain; dysaesthesia | Both “uncommon” (1 in 1,000 to 1 in 100) | EU tirzepatide information [4] |
| Unusual skin sensations such as burning, tingling or pricking | Listed among possible side effects | Canadian patient information [3] |
The injection site and the skin
The clearest source of soreness is the injection itself. In the pooled trials, injection site reactions were much more common in people who developed antibodies to tirzepatide (11.3%) than in those who did not (1%). [1] The Canadian monograph lists the terms behind that row, including pain, swelling, hardening, irritation and tingling at the site. [3] Hypersensitivity reactions, mostly rashes and itching, were also more common than on placebo, both within a day of a dose (2.1% vs 0.4%) and later (3.5% vs 2.7%). [1]
Dysesthesia, a burning, tingling or otherwise unpleasant skin sensation, is the other skin-level finding. It was uncommon in the trials, [1] and the Canadian monograph also lists it from post-marketing reports. [3] Such sensations can be confused with aching, which is one reason to describe exactly where and how it hurts.
Muscle, weight and uric acid in the research
Zepbound®’s label says tirzepatide lowers weight with greater loss of fat mass than lean mass. [1] In SURMOUNT-1, average weight fell by 15.0% to 20.9% over 72 weeks depending on dose, against 3.1% on placebo. [7] Weight loss of that size changes how muscles and joints are loaded, in both directions.
A 2026 analysis of FDA spontaneous reports found no overall musculoskeletal signal for incretin medicines, but tirzepatide was linked to reports of muscle atrophy and a neck mass, and musculoskeletal reports with GLP-1 medicines and tirzepatide tended to start within 30 days. [5] Spontaneous reports are shaped by who chooses to report and cannot show cause or frequency.
For joints, two pieces of research point the other way. In a post hoc analysis of SURMOUNT-1, all three tirzepatide doses lowered blood uric acid compared with placebo, and weight loss explained about 73% of the change. [6] High uric acid is what drives gout, and obesity is a gout risk factor. [11] A 2026 narrative review on low back and knee pain concluded that weight reduction improves pain and function in these conditions, while stressing that GLP-1-based medicines are not pain treatments in themselves. [8]
Why aches can appear during treatment
Three explanations are supported by the documents or by public health sources.
- Fluid and electrolyte loss. Nausea, vomiting and diarrhea, most common while the dose is being raised, can lead to dehydration. [1] MedlinePlus lists muscle cramps among signs of mild to moderate dehydration, and electrolyte imbalance among causes of muscle pain. [9][12]
- General malaise. The fatigue row in Table 1 includes malaise, a general feeling of being unwell. [1]
- A change in activity. Many people start exercising while on Zepbound®; MedlinePlus names overuse, tension and exercise injury as the commonest causes of muscle pain. [9]
Other things that cause aches
MedlinePlus lists flu and other infections, fibromyalgia, lupus, polymyalgia rheumatica, electrolyte problems and certain medicines, including statins for cholesterol and ACE inhibitors for blood pressure, among causes of muscle pain. [9] For joints it names osteoarthritis, gout, bursitis, tendinitis, rheumatoid arthritis and infections. [10] Many people starting Zepbound® already take a statin or blood pressure medicine, so it is worth noting whether an ache began after any medicine change.
Gout deserves its own mention. It typically causes sudden, intense pain, swelling, redness and warmth in a single joint, often the big toe and often at night. [11]
What general guidance suggests
The Zepbound® Medication Guide has no ache-specific advice. It asks you to drink fluids to reduce the chance of dehydration and to rotate the injection site every week, using a different spot even within the same area. [2] For injection site soreness, rotation is the step the label itself describes. [1]
For muscle pain from overuse, MedlinePlus suggests rest, ice for the first one to three days and then heat, gentle stretching and massage, and names acetaminophen or ibuprofen as options; [9] for joint pain it adds warm baths and stretching. [10] Ask a pharmacist which pain reliever suits you, since Zepbound® can affect how some oral medicines are absorbed. [1] If an ache began after starting or changing a medicine such as a statin, MedlinePlus advises contacting your provider. [9]
Zepbound® and Mounjaro® are registered trademarks of Eli Lilly and Company. PepLabo is not affiliated with or endorsed by Eli Lilly and Company.
When to get help
| Sign | Who to contact | How fast | Source |
|---|---|---|---|
| Muscle pain with sudden weight gain, water retention or passing much less urine, or with shortness of breath or trouble swallowing | Emergency services (911 or local number) | Emergency | MedlinePlus [9] |
| Swelling of the face, lips or throat, severe rash, or trouble breathing after a dose | Stop Zepbound® and get emergency help | Emergency | Medication Guide [2] |
| Muscle weakness, inability to move a body part, high fever, very stiff neck or vomiting with aches | Medical help right away | Emergency | MedlinePlus [9] |
| A suddenly hot, red, swollen and very painful joint | Your clinician the same day | Today | MedlinePlus [10][11] |
| Ongoing vomiting or diarrhea with cramps, thirst or dark urine | Your prescriber, promptly | Today | Medication Guide [2] |
| Muscle pain lasting more than 3 days, or that began after starting or changing a medicine | Contact your provider | At your next appointment | MedlinePlus [9] |
