Myths about peptides, read against the science
Each article takes one claim people repeat online and reads it against trials, labels, regulators, and reviews.
Explore the myths
Side effects and safety
Worries about symptoms, organs, and warning signs.
01Do GLP-1 peptides cause hair loss?Yes, some people lose more hair on these peptides. Not many. And the hair grows back.02Do GLP-1 peptides damage teeth?Not directly. The peptide doesn't attack teeth. The conditions around it can.03Do GLP-1 peptides cause erectile dysfunction?There's one observational study suggesting a small effect in non-diabetic obese men. The evidence is thin, and no trial designed to test this has reported yet.04Do GLP-1 peptides lower libido?There's no clear mechanism in the literature that says the peptide lowers libido. The signal hasn't been studied directly in a trial.05Does Ozempic cause "Ozempic face"?The face does look different. The reason is fat loss, not the peptide.06Do GLP-1 peptides cause loose skin?Loose skin follows weight loss, not the peptide itself.07Do GLP-1 peptides cause muscle loss?Yes, some lean-mass loss happens. And that's true of every weight-loss method, not just peptides. The body-composition studies show fat falls more than lean.08Do GLP-1 peptides cause vitamin deficiencies?The peptide doesn't remove vitamins from the body. It reduces how much food the body takes in. If the food drops without the nutrient quality going up, vitamin intake can fall below what the body needs.09Do GLP-1 peptides cause dehydration?Not directly. The peptide doesn't dry the body out. Eating and drinking less around the peptide can.10Do GLP-1 peptides cause constipation?Yes. Constipation is one of the most common side effects of these peptides.11Do GLP-1 peptides cause nausea?Yes. And it's expected. Nausea is built into how this class of peptides works.12Does Ozempic cause "stomach paralysis"?Slower stomach emptying is part of how these peptides work. "Paralysis" overstates what's happening.13Do GLP-1 peptides damage the kidneys?Not directly. The kidney risk in the literature runs through severe dehydration from GI symptoms.14Do GLP-1 peptides damage the liver?Direct liver injury isn't a primary safety signal for these peptides.15Do GLP-1 peptides cause gallbladder problems?Yes. And so does fast weight loss itself. This is a real safety topic.16Do GLP-1 peptides cause pancreatitis?Acute pancreatitis is a labeled warning. The absolute rate in trials is low. The symptom pattern is severe persistent abdominal pain.17Do GLP-1 peptides cause thyroid cancer?The boxed warning is based on rat studies. The human evidence so far doesn't show a population-level cancer effect. A specific high-risk subgroup is contraindicated.
Body, weight, and fertility
Visible changes, muscle, metabolism, libido, and reproduction.
18Do GLP-1 peptides cause depression or suicidal thoughts?In January 2026, the FDA reviewed 91 studies covering about 108,000 patients and found no increased risk. Warning language is being removed.19Do GLP-1 peptides cause infertility?Infertility isn't an established effect. The label asks people to stop the peptide at least two months before a planned pregnancy because of how long it stays in the body.20Do GLP-1 peptides affect birth control?For tirzepatide (Mounjaro and Zepbound), the label is explicit. For semaglutide (Ozempic and Wegovy), it isn't.21Do GLP-1 peptides cause blindness?Rare, but real. The eye-disease research shows a small signal involving an optic-nerve condition, and the absolute rates are low.22Do people regain the weight when they stop?Yes, much of it. About two-thirds of the lost weight came back in the studies that followed people after they stopped.23Do GLP-1 peptides permanently damage metabolism?No. Significant weight loss reduces resting energy expenditure with or without the peptide. The adaptation is real but not specific to peptides.24Are weight loss peptides addictive?Are weight loss peptides addictive? Not in the stimulant-opioid-sedative sense. Current evidence points toward reduced compulsive reward signaling, not escalating reinforcement.
Trust, sourcing, and quality
What a source, COA, or side effect can prove, and what it cannot.
25Are all peptide sources the same?No. The molecule is the same on paper. The supply system isn't.26Does a certificate of analysis prove a peptide is trustworthy?A certificate of analysis is necessary, not sufficient.27Are side effects proof of bad peptide quality?Are side effects proof of bad peptide quality? No. In GLP-class compounds, low-to-moderate GI effects are often part of the expected mechanism pattern, not automatic evidence of defective product.