Researched and fact-checked in-house against primary literature and regulator records. Not reviewed by a named clinician — how we work.
Evidence-rated reference Updated August 2026
We sell nothing. No vendor sponsorship. Editorial policy
Pepteyes .com

Cheat Sheet · Side effects

Side effects, by compound family

What actually shows up, why it happens, and the first thing to try — grouped by the compound families that share their side-effect profile. The red-flag list at the end is the one to memorise.

GLP-1s (Sema, Tirz, Reta)

Very Common
Nausea and vomiting — most common on ramp-up or a dose increase. Fix Slow your titration. Dose at night. Avoid high-fat meals the same day.
Constipation or diarrhea — GI motility slows significantly. Fix More fiber and water. Magnesium citrate at night. Do not rush to higher doses.
Muscle loss — rapid fat loss without training accelerates it. Fix Resistance train 3–4x per week. Hit protein targets daily.
Injection site redness or a lump — normal for SubQ early on. Fix Rotate sites every injection. Let the solution warm to room temp first.

GH Secretagogues (CJC, Ipa, GHRP)

Common
Water retention and bloat — GH holds water, especially early. Fix Cut sodium. Usually resolves in 2–3 weeks; lower the dose if severe.
Carpal tunnel or tingling hands — pressure from the fluid retention. Fix Lower the dose or take a week off. Usually temporary.
Increased hunger (GHRP-6) — ghrelin stimulation drives appetite hard. Fix Switch to Ipamorelin, or dose only at night.
Drowsiness — expected when dosed before bed — that timing is intentional. Fix Keep the nighttime dosing. Avoid pre-workout dosing.

BPC-157 and TB-500

Generally Well Tolerated
Nausea (oral BPC) — more common with the oral route. Fix Take with food, or switch to injectable SubQ.
Injection site irritation — mild redness or soreness. Fix Rotate sites, warm the solution to room temp, inject slowly.
Cancer growth concern (theoretical) — angiogenesis promotion is the main debate. Note Do not use with a history of cancer or active tumors.

NAD+

Common with IV
Flushing, chest tightness, nausea (IV) — common when the drip runs too fast. Fix Slow the drip. Run 250mg over a minimum of 2–4 hours.
Insomnia — the energizing effect disrupts sleep taken too late. Fix Take SubQ or oral doses before noon.
Headache — usually dehydration during IV sessions. Fix Hydrate before and during the infusion. Electrolytes help.

Melanotan II and PT-141

Common
Nausea and facial flushing — very common, especially the first few uses. Fix Start at 0.5mg or lower. Dose at night.
Mole darkening (MT2) — increased pigmentation can darken existing moles. Note Get moles checked before and during use. Stop if any mole changes.
Increased blood pressure — a transient spike after dosing. Fix Monitor BP. Avoid entirely with cardiovascular issues.

Universal Red Flags — Stop and Reassess

Important
Severe allergic reaction — rash, hives or difficulty breathing after an injection — stop immediately and seek emergency care.
Persistent elevated resting heart rate — especially with Retatrutide. Reduce the dose or stop.
Pancreatitis symptoms — severe upper-abdominal pain on a GLP-1 — stop immediately and get bloodwork.
Vision changes — blurring is documented with GLP-1 use. Stop and see a doctor.
Blood sugar crashes — dizziness, sweating, confusion — especially with IGF-1 LR3. Keep fast carbs nearby.
Cloudy or discolored peptide solution — never inject it. Discard it.

Reminder

Side effects vary with the person, the dose and the quality of the compound, and this list is not exhaustive. Not medical advice. If something feels wrong, stop the compound and talk to a doctor.