Abnehmspritze: die Nebenwirkungen und wie Sie sie in den Griff bekommen

What this guide covers

Die häufigsten Nebenwirkungen der Abnehmspritze sind Magen-Darm-Beschwerden, dosisabhängig und meist in den ersten Wochen am stärksten. Hier erfahren Sie, was die Fachinformationen zu Semaglutid (Ozempic, Wegovy) und Tirzepatid (Mounjaro, Zepbound) zeigen, wie lange es dauert und wann Sie ärztlichen Rat einholen sollten. This is patient education, not a substitute for the prescriber who knows your case. Generic names sit next to brand names throughout: semaglutide (Ozempic, Wegovy), tirzepatide (Mounjaro, Zepbound).

Key points

• The short answer: mostly digestive, mostly early. Abnehmspritze is the German umbrella term for the injectable GLP-1 weight-loss medications: semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound). The most common side effects across all of them are gastrointestinal: nausea, constipation, diarrhea, vomiting, indigestion, and reduced appetite. In the STEP, SUSTAIN, SURMOUNT, and SURPASS trials these were reported most often, were usually mild to moderate, and clustered in the first weeks of treatment and just after each dose increase. For most people they ease as the body adjusts to a given dose. The same slowed digestion that drives the side effects is part of how these medications work, which is why the two tend to arrive together.
• Nausea and the digestive cluster. Nausea is the side effect people ask about most. These medications slow how quickly the stomach empties, so food sits longer than you are used to, and they act on the brain pathways that regulate appetite and nausea. It is usually heaviest in the first one to two weeks of a new dose and fades from there. What tends to help: smaller meals eaten slowly, lower-fat meals because fat is the slowest thing to leave the stomach, cold slow sips of water, and not lying down right after eating. Constipation and diarrhea come from the same slowed, altered digestion; the gut can go either way. If nausea tips into vomiting that stops you keeping fluids down, that moves into call-your-doctor territory.
• Fatigue, headache, and the early adjustment. Beyond the gut, the early weeks often bring fatigue, headache, or lightheadedness. These are usually not the drug acting directly but a knock-on effect of eating and drinking much less: you can run low on fluid and electrolytes, and that shows up as tiredness and headache. The fix is rarely to force large meals a slow stomach will not tolerate; it is to make smaller meals count, lead with protein, and keep fluids and electrolytes steady through the day. If fatigue is persistent and severe rather than the early-weeks dip, that is worth a conversation with your clinician, since low B12, iron, or thyroid problems can look identical.
• Muscle and hair: side effects of losing weight fast. Some effects come from rapid weight loss itself rather than the medication acting directly. A share of the weight lost is lean muscle, not just fat, which is why a protein target around 1.2 to 1.6 grams per kilogram of body weight per day and resistance training come up so often as protective habits. Temporary hair shedding (telogen effluvium) can follow any rapid weight loss and usually recovers; it is tied to the speed of loss and to running low on protein and iron, not to a direct drug toxicity. Neither is a reason to stop on its own, but both are reasons to keep protein and basic nutrition steady.
• The serious but rare risks the label flags. Most people never meet these, but they are the ones to know by name. The FDA labels for semaglutide and tirzepatide carry a boxed warning about thyroid C-cell tumors seen in rodents, so these medications are not for people with a personal or family history of medullary thyroid carcinoma or MEN 2. The labels also list pancreatitis (severe, persistent abdominal pain, often radiating to the back), gallbladder problems, low blood sugar especially when combined with insulin or a sulfonylurea, dehydration-related kidney injury from prolonged vomiting or diarrhea, and serious allergic reactions. These are uncommon, but they are same-day call signals rather than wait-and-see symptoms.

Frequently asked questions