Peptide therapy: what it is, what the evidence shows, and key safety considerations

Peptide therapy has attracted attention for claims ranging from improved recovery and metabolism to “anti‑aging.” This article explains what peptides are, summarizes the best available human evidence, compares common forms and uses, and outlines monitoring and safety considerations you should know before considering treatment.

What is peptide therapy?

Peptides are short chains of amino acids—smaller than full proteins—that act as signaling molecules in the body. In medicine, some peptides are prescribed drugs that mimic or modify natural signals (for example, insulin or GLP‑1 receptor agonists). Other peptides are experimental agents with limited human data and mostly preclinical or small clinical studies.

If you’ve searched for “what is peptide therapy,” the short answer is: it broadly refers to medical or experimental use of these short amino‑acid chains to produce biological effects. How established a peptide is depends on regulatory approval and the strength of clinical trials.

Types and examples

Prescription, well‑studied peptides

• Insulin: an essential peptide hormone used for type 1 and advanced type 2 diabetes with decades of clinical evidence.

• GLP‑1 receptor agonists (liraglutide, semaglutide and others): peptide-based diabetes medications with large randomized trials supporting glucose control and, for many agents, weight loss.

• Somatropin (recombinant human growth hormone) and teriparatide (PTH 1‑34): approved for specific endocrine or bone indications with established dosing protocols.

• Tesamorelin: approved for HIV‑associated lipodystrophy.

Experimental or less‑proven peptides

• Examples include BPC‑157, TB‑500, CJC‑1295, ipamorelin and others commonly discussed online. Most of these have limited human data; evidence is primarily animal studies, case reports, or small uncontrolled trials.

What does the evidence say?

H3: Strong, high‑quality evidence
A subset of peptides are supported by rigorous randomized controlled trials and regulatory approval. These medications have defined indications, known benefit‑risk profiles, and standardized dosing overseen by clinicians. Examples: insulin for diabetes; GLP‑1 receptor agonists for type 2 diabetes and weight management; teriparatide for osteoporosis.

H3: Limited or emerging evidence
Many peptides marketed for “recovery,” “performance,” or “anti‑aging” lack robust human trials. Preclinical data can indicate biological plausibility, but animal results do not reliably predict clinical outcomes in people. Small open‑label studies or case series are hypothesis‑generating but insufficient to establish effectiveness or safety.

H3: Comparative considerations

• Approved peptide therapies are prescribed with monitoring and known adverse effects; their risks and benefits are quantified in trials.

• Experimental peptides may have anecdotal reports of benefit but lack standardized manufacturing, dosing, and safety data.

• Route of administration (subcutaneous injection, intranasal, oral formulations) affects absorption; many peptides require injection because oral bioavailability is poor.

Dosing and usage considerations

• Prescription peptides: dosing depends on the medication, indication, and individual factors. Clinicians typically start at a recommended initial dose and titrate to effect while monitoring for side effects.

• Experimental peptides: dosing is often not standardized. Reports of dose ranges online are inconsistent and may not be safe or effective.

• Administration: many peptides are given by subcutaneous injection; some are available as daily, weekly, or other schedules depending on formulation.

• Practical considerations: storage, sterility, and accurate reconstitution (if required) are critical. Improper handling can alter potency or introduce contamination.

Always discuss specific dosing, titration, and administration with a licensed clinician; do not rely on unverified online protocols.

Biomarkers and monitoring

Appropriate monitoring depends on the peptide and the intended effect. Common biomarkers that clinicians may track include:

• IGF‑1: used to monitor growth hormone axis activity and to help dose therapies that affect GH signaling.

• Fasting glucose: important for peptides that influence metabolism or glucose regulation (for example, GLP‑1 agonists or growth hormone–related therapy).

• CRP (C‑reactive protein): a general inflammation marker that may be measured when assessing systemic effects or monitoring inflammatory responses.

Other tests sometimes used include lipid panels, liver and kidney function, electrolytes, and hormone panels. Monitoring schedules are individualized and should be directed by a clinician.

Safety, risks, and who should avoid peptide therapy

Major safety considerations

• Avoid self‑injection without medical oversight. Contamination, incorrect reconstitution, and dosing errors are common risks with unsupervised use.

• Sourcing matters: unregulated online suppliers and non‑pharmaceutical compounding can introduce contaminants, incorrect doses, or counterfeit products.

• Immune reactions and injection‑site complications: local reactions, allergic responses, or antibody formation can occur.

• Metabolic effects: some peptides can alter glucose metabolism and appetite; monitoring fasting glucose is often necessary.

• Potential proliferative risk: therapies that increase IGF‑1 or growth signaling may theoretically affect cell proliferation. People with active cancer or a high risk of malignancy should discuss risks carefully with their oncologist or endocrinologist.

Who should generally avoid peptide therapy without strict medical oversight

• Pregnant or breastfeeding people.

• Individuals with active malignancy or recent history of cancer unless cleared by an oncologist.

• People with uncontrolled diabetes, significant cardiac, liver, or renal disease without specialist input.

• Children, unless a pediatric specialist has established an indication and safe dosing.

If you are considering peptides, use licensed prescribers and certified pharmacies, and insist on a plan for baseline and follow‑up testing.

Practical steps before starting peptide therapy

• Confirm the indication: ask whether the peptide is approved for your condition or considered experimental.

• Verify the evidence: request peer‑reviewed studies or guidelines that support the proposed use.

• Discuss monitoring: agree on which biomarkers will be measured (e.g., IGF‑1, fasting glucose, CRP) and the frequency of follow‑up.

• Check sourcing and handling: ensure medication comes from a regulated manufacturer or certified compounding pharmacy and that storage/administration instructions are clear.

• Review contraindications and interactions with your current medications.

Takeaways and conclusion

Peptide therapy is a broad category that includes well‑established prescription drugs supported by high‑quality evidence and many experimental peptides with limited human data. For approved peptide medications—such as insulin, GLP‑1 receptor agonists, teriparatide, and others—randomized trials and regulatory review define safe dosing, monitoring, and expected effects. Experimental peptides often lack standardized dosing, rigorous safety data, and reliable manufacturing.

Safety is paramount: avoid self‑injection from unverified sources, insist on clinician supervision, and use appropriate biomarker monitoring (IGF‑1, fasting glucose, CRP, and others as indicated). People who are pregnant, breastfeeding, have active cancer, or significant uncontrolled medical conditions should generally avoid unsupervised peptide use.

If you’re considering peptide therapy, discuss benefits, alternatives, monitoring, and sourcing with a qualified clinician so decisions are based on evidence and individualized risk assessment.

Join Mito to test 100+ biomarkers and get concierge-level guidance from your care team