Peptides 101
Alan Peptides 101
Educational information only

What 15 popular compounds are, what they're studied for, and what's known about the risks.

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A note from Alan

I’m Alan. If you found me through my skin journey on TikTok, you already know I don’t gatekeep.

This is everything I’ve learned about peptides, laid out the way I wish someone had explained it to me: what’s proven, what’s just marketing, and what the risks look like. Wherever you’re starting from, I’m glad you’re here.

Alan

GHK-Cu

Naturally occurring

A naturally occurring three-amino-acid peptide that binds to copper. It is studied in skin, collagen, and wound-related research.

Benefits

Studied for supporting healthier-looking skin, collagen production, wound healing, and hair growth. Injectable benefits are not established.

Side effects

Topical products may cause redness, irritation, or an allergic reaction. The FDA says injectable GHK-Cu has limited human safety data and may carry risks involving immune reactions, aggregation, and peptide impurities.

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Retatrutide

Experimental · in clinical trials

An experimental peptide that activates three receptors involved in appetite, blood sugar, and metabolism: GLP-1, GIP, and glucagon.

Benefits

Clinical trials have found significant weight reduction and improvements in certain metabolic measurements. May support significant weight loss by reducing appetite and activating metabolic pathways involved in blood sugar, energy use, and fat metabolism.

Side effects

Nausea, diarrhea, vomiting, and constipation were common in trials. Some participants experienced increased heart rate.

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Tesamorelin

Rx product approved for one specific use

A laboratory-made version of a growth hormone-releasing hormone. It stimulates the body to release more growth hormone.

Benefits

A specific prescription tesamorelin product is FDA-approved to reduce excess abdominal fat in certain adults with HIV-associated lipodystrophy. It is not approved as a general weight-loss treatment.

Side effects

Swelling, fluid retention, joint pain, carpal tunnel symptoms, increased blood sugar, elevated IGF-1, allergic reactions, and injection-site reactions. It may be inappropriate for people with certain cancers or pituitary conditions.

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TB-500

Experimental · not FDA-approved

An experimental synthetic peptide fragment related to thymosin beta-4. It is not an FDA-approved medication.

Benefits

Commonly marketed for supporting wound healing, flexibility, tissue repair, and physical recovery. These benefits are not proven in humans.

Side effects

FDA has not identified adequate human-exposure data, so its side effects and long-term risks are unknown. Possible concerns include immune reactions, peptide aggregation, impurities, and contamination.

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BPC-157

Experimental · mostly animal research

An experimental peptide made from 15 amino acids. Most supporting evidence comes from laboratory or animal research.

Benefits

Studied mainly in animals for digestive health, wound healing, tendons, ligaments, and injury recovery. Human benefits remain unproven.

Side effects

Human side effects are not adequately known. The FDA identifies possible risks involving immune reactions, aggregation, peptide impurities, and difficulty confirming the quality of the active ingredient.

Sources

KPV

Experimental · human benefits not established

A small peptide made from three amino acids: lysine, proline, and valine. It is related to part of the alpha-melanocyte-stimulating hormone sequence.

Benefits

Studied for potentially calming inflammation and supporting the skin, gut, and wound-healing processes. Human benefits are not established.

Side effects

No adequate human-exposure data are available, so its side effects and long-term risks are unknown. Possible concerns include immune reactions.

Sources

MOTS-C

Experimental · no established human benefit

A small peptide naturally produced from genetic information inside mitochondria, which are structures involved in cellular energy.

Benefits

Studied for possible support of energy use, insulin sensitivity, exercise performance, and metabolic health. It has no established human medical benefit.

Side effects

The FDA has not identified adequate human-exposure data. Possible risks include immune reactions, aggregation, and peptide impurities.

Sources

MT-1

Approved implant exists · MT-1 is unregulated

Afamelanotide is a synthetic version of a hormone involved in skin pigmentation. It is related to what online sellers may call Melanotan I or MT-1.

Benefits

The approved afamelanotide implant helps certain patients tolerate light exposure and also increases skin pigmentation. Unregulated MT-1 is not equivalent to the approved implant.

Side effects

Implant-site reactions, nausea, throat discomfort, cough, fatigue, dizziness, sleepiness, skin darkening, and new or changing moles. Patients using the approved product are advised to receive regular skin examinations.

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MT-2

Unapproved · FDA safety concerns

An unapproved synthetic compound that activates melanocortin receptors involved in pigmentation and other body functions.

Benefits

Marketed for increasing skin pigmentation or tanning and sometimes for increasing sexual arousal. It is unapproved, and these are not established safe medical benefits.

Side effects

Reported effects include nausea, flushing, reduced appetite, skin darkening, changing moles, and prolonged erections. FDA notes serious case reports involving priapism, melanoma, neurological toxicity, and sympathomimetic toxicity. A case report does not always prove that MT-2 caused the event, but it identifies a potential safety concern.

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GLOW

Blend · not adequately studied
Blend of
GHK-CuBPC-157TB-500

Benefits

Marketed for supporting brighter-looking skin, collagen, hair growth, and tissue recovery. The complete blend has not been adequately studied in humans.

Side effects

Potential risks include reactions associated with each ingredient, unknown interactions, contamination, immune reactions, and peptide impurities.

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Glutathione

Naturally occurring antioxidant

A naturally occurring antioxidant made from three amino acids. It is technically a tripeptide.

Benefits

Helps protect cells from oxidative stress and supports normal antioxidant and detoxification processes. Skin-lightening and broad wellness claims are not fully established.

Side effects

Oral products may cause digestive discomfort. Injectable products add risks involving allergy, contamination, and sterility. FDA has reported endotoxin-related reactions that can range from fever and chills to severe illness or death.

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NAD+

Coenzyme · not a peptide

A coenzyme found in every living cell. It helps cells transfer energy and is not a peptide.

Benefits

Helps cells convert nutrients into energy and supports normal cellular metabolism. Claims that injections increase energy, promote weight loss, or reverse aging have not been proven.

Side effects

FDA has received reports following compounded NAD+ injections involving severe chills, shaking, vomiting, and fatigue. Some reactions were consistent with bacterial-endotoxin contamination and required medical treatment.

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CJC/Ipamorelin

Experimental · not FDA-approved
Blend of
CJC-1295Ipamorelin

A combination of two experimental substances that affect growth-hormone signaling. CJC-1295 acts on growth hormone–releasing pathways, while ipamorelin stimulates the ghrelin receptor.

Benefits

Marketed for increasing growth-hormone signaling to support sleep, recovery, muscle development, and fat loss. These are not FDA-approved benefits.

Side effects

CJC-1295 has been associated with increased heart rate and systemic vasodilation. FDA also identifies immune and impurity concerns for both substances. Serious events occurred in a study using intravenous ipamorelin, although the relevance to other routes remains uncertain.

Sources

Wolverine

Blend · unproven
Blend of
BPC-157TB-500

Benefits

Marketed for supporting tendons, ligaments, joints, injury healing, and workout recovery. These combined benefits remain unproven.

Side effects

Human safety data for the combination are inadequate. Possible concerns include immune reactions, contamination, peptide impurities, and unknown effects from combining the substances.

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