PeptIQ is for adults 18+ and never gives dosing advice. Talk with a licensed clinician before starting, stopping, or changing any peptide, hormone, or medication. This guide is educational, not medical advice.
Peptide content is everywhere right now. A Center for Countering Digital Hate review found TikTok videos promoting steroids, peptides and SARMs had at least 587 million US views over three years, about 420 million of them from users aged 18–24 (CCDH). In a UK Anti-Doping survey of 16–25-year-olds, 5% said they saw peptide ads every day (UKAD).
So here's an honest look at the evidence, including where there isn't much.
First, "peptide" covers two very different things
FDA-approved peptide medicines, prescribed and monitored. Insulin, semaglutide (Wegovy/Ozempic) and tirzepatide have been through large trials. They have labels, known side effects and a clinician watching labs.
Unapproved, compounded-from-unapproved or "research use only" (RUO) products. These include retatrutide, BPC-157, CJC-1295, MK-677 and melanotan II. Nobody has established them as safe and effective for any use. The FDA has warned companies selling GLP-1-type drugs, retatrutide among them, "falsely labeled 'for research purposes' or 'not for human consumption'" and says these products "are of unknown quality and may be harmful" (FDA).
Most of what follows is about the second group.
Retatrutide ("reta")
- Not FDA-approved. It's still investigational. The FDA says retatrutide "cannot be used in compounding under federal law" and has warned telehealth companies, API distributors and outsourcing facilities over it (FDA; warning letter).
- Studied in adults with obesity, under trial monitoring. In the Phase 2 NEJM trial, 73–94% of participants on retatrutide reported adverse events, compared with 70% on placebo. Most were gastrointestinal. Between 6% and 16% stopped because of side effects (none stopped on placebo). Heart rate rose with dose, and one serious case of acute pancreatitis occurred (NEJM 2023). Phase 3 trials enroll adults (ClinicalTrials.gov).
- What that means for an 18-year-old buying it online: you'd be using a drug with no approval and no data in your age group. The vial may not contain what the label says, and nobody is monitoring you the way trial participants were.
Testosterone
- Testosterone is FDA-approved only for men whose low testosterone comes from specific medical conditions, confirmed by lab tests. In 2015 the FDA added labeling about a possible increased risk of heart attack and stroke (FDA 2015). Labels state that safety and effectiveness in males under 18 "have not been established" (Aveed label).
- Current labels list serious reactions reported with abuse: cardiac arrest, heart attack, cardiomyopathy, stroke, liver toxicity, major depression, mania and psychosis. They also list testicular atrophy, subfertility and infertility, plus "premature closure of bony epiphyses with termination of growth" in adolescents (label).
- Dependence and shutdown. The label describes withdrawal after high-dose use that can last "weeks or months": depression, fatigue, craving and hypogonadotropic hypogonadism, meaning your own production stays suppressed (label). Starting at 18, when your hormonal axis is healthy, means trading a working system for one you may have to manage for years.
SARMs and growth-hormone secretagogues (MK-677 and others)
- The FDA has issued a warning aimed specifically at teens and young adults using SARMs. It links them to liver injury and failure, heart attack, stroke, psychosis and infertility (FDA).
- In one online survey of SARM users, 72% were 18–29. More than 90% hadn't consulted a physician, and more than half reported side effects (Int J Impot Res).
- In a December 2025 warning letter, the FDA said MK-677 can cause water retention, changes in glucose metabolism and insulin sensitivity, and possibly heart failure, and that "long-term effects ... are unknown." The FDA found it hidden in a children's "growth" product (FDA). Evidence gap: the worry that raising IGF-1 before growth plates close could affect growth is mostly theoretical. Healthy teens have never been studied.
GLP-1s in teens: the approved path looks very different
Semaglutide (Wegovy) is approved for adolescents 12 and older with obesity, based on the STEP TEENS trial (NEJM 2022). The FDA's review noted that adolescents had more gallstones, gallbladder inflammation, low blood pressure and rash than adults did (FDA review). Pediatric guidelines pair it with intensive lifestyle treatment and ongoing medical supervision (AAP 2023).
That's the model to follow: a diagnosis, an approved product, a clinician and follow-up labs.
Even approved drugs go wrong without supervision
US poison centers received 4,414 GLP-1 calls in 2023, compared with 234 in 2014. Three-quarters were dosing errors (PMC). In California, 33 of 36 compounded-GLP-1 exposures were administration errors (Ho et al. 2025). The FDA has warned about compounded semaglutide overdoses of 5–20 times the intended amount caused by mixing up units (FDA).
What we don't know
- No major US youth survey (YRBS, Monitoring the Future) asks about peptides, retatrutide or non-medical GLP-1 use. MTF tracks anabolic steroids: 0.9% of 8th, 10th and 12th graders reported past-year use in 2025 (MTF).
- Social-media data measures exposure, not use. We don't know how many 18–24-year-olds actually use research peptides.
- "No data" doesn't mean "safe." It means nobody has checked.
Our take
If you're under 25, don't start any of these on your own. See a licensed clinician, get baseline labs, and stick to approved products for real diagnoses. PeptIQ is a tracking tool, not a prescriber, and nothing here is dosing advice.