The short answer.
Peptide therapy is not appropriate for patients with active cancer (especially growth-hormone-axis peptides), pregnancy or breastfeeding, severe uncontrolled cardiovascular disease (for selected peptides), certain endocrine disorders without specialist co-management, and patients on medications with known peptide interactions. Each peptide has its own specific contraindication list. We screen at intake before recommending any peptide therapy.
The clinical detail.
Contraindications for peptide therapy are peptide-specific. Below is the practical screening framework we apply at intake, organized by peptide category. Patients in any of these categories should not start peptide therapy without addressing the contraindication first — sometimes peptide use becomes appropriate later, sometimes it doesn't.
Growth-hormone-axis peptides (sermorelin, CJC-1295, ipamorelin).
- Active cancer. Absolute contraindication. Growth-hormone signaling intersects with cell-growth pathways; the theoretical concern is that increasing GH/IGF-1 in a patient with active malignancy could affect tumor biology. Patients with a personal cancer history in confirmed remission may be candidates with oncology clearance; the timeline since remission matters.
- Strong family history of certain cancers. Relative concern. We evaluate case by case with input from the patient's primary or oncology team where appropriate.
- Active diabetic retinopathy. GH-axis activation can theoretically worsen proliferative retinopathy.
- Acromegaly or other pituitary adenoma. Absolute contraindication.
- Severe insulin resistance or poorly controlled type 2 diabetes. GH-axis stimulation can affect glucose metabolism. We address glucose control first.
- Pregnancy or breastfeeding. Not appropriate.
- Pediatric use. Sermorelin had historical use in pediatric growth-hormone deficiency under pediatric endocrinology. The functional-medicine adult use is a different population.
Sexual-function peptides (PT-141 / bremelanotide).
- Uncontrolled hypertension. PT-141 can produce transient blood-pressure elevation; not appropriate for patients with poorly controlled hypertension.
- Severe cardiovascular disease. Cardiology clearance required.
- Pregnancy or planning pregnancy. Not appropriate.
- History of melanoma or active hyperpigmentation concerns. Melanocortin activation can drive pigmentation changes.
- Concurrent use of certain medications. Caution with antihypertensives and other CNS-active medications. We review the medication list at intake.
Tissue-repair peptides (BPC-157).
- Active malignancy. The angiogenic and tissue-repair signaling has a theoretical interaction with tumor biology; we avoid in active cancer pending more data.
- Pregnancy or breastfeeding. Not appropriate; limited human data.
- Patients seeking to avoid injection. BPC-157 is most commonly used as subcutaneous injection; oral preparations are less reliable for systemic effect.
Metabolic peptides (AOD-9604).
- Active malignancy. Same growth-axis concern.
- Pregnancy or breastfeeding. Not appropriate.
- Patients expecting it to substitute for diet and training. AOD-9604 is an adjunct, not a primary intervention. We don't prescribe it as a weight-loss "easy button."
NAD+ infusions.
- Active malignancy. NAD+ has broad cellular effects; we avoid in active cancer pending more data.
- Pregnancy or breastfeeding. Not appropriate; limited safety data.
- Severe cardiovascular instability. Infusion adds volume and stimulation; we screen.
- Significant infusion-rate intolerance. NAD+ infusions can cause flushing, chest pressure, and discomfort if infused too quickly. Slow infusion mitigates but doesn't eliminate.
Cross-category contraindications.
- Pregnancy and breastfeeding. No therapeutic peptide we offer has adequate pregnancy safety data. Conservative default is no peptide therapy.
- Severe immunosuppression. Immunomodulatory effects of some peptides are not well characterized in this population.
- Patients unable or unwilling to follow monitoring schedule. A patient who won't return for follow-up labs or visits is not an appropriate candidate — for any peptide.
- Patients sourcing peptides from research-chemical channels. We do not prescribe peptides as a "complement" to research-chemical use because we cannot verify what the patient is actually using.
- Patients seeking peptides for indications without evidence support. We don't prescribe peptides for indications where the evidence doesn't support a clinical effect.
Relative contraindications worth discussing.
- Personal cancer history in remission — timeline since remission, type of cancer, oncology clearance.
- Family history of hormone-sensitive cancers or pituitary disease.
- Active or recent thrombotic event.
- Active mental health crisis or unstable medication regimen.
- Substance use disorders that may complicate adherence or interpretation of effect.
- Patients on weight-loss medications (GLP-1 agonists, etc.) prescribed elsewhere — some interactions to consider.
What screening looks like at intake.
Before starting any peptide protocol, we obtain a comprehensive medical history, current medication and supplement list, cancer screening status, cardiovascular history, family history relevant to the specific peptide, and baseline labs (varies by peptide; IGF-1 for GH-axis peptides, blood pressure check for PT-141, metabolic panel for AOD-9604, etc.). Patients with any absolute contraindication are not initiated. Patients with relative contraindications are discussed and decided case by case — sometimes with specialist input.
Where this fits in our methodology.
The CLARITY methodology builds in contraindication screening at every protocol entry point. Peptide therapy is not a default offering — it's a specific intervention used when clinically appropriate, not when requested. Patients deserve a clear no when peptides aren't appropriate, not a sales pitch. See the methodology in full.
For specific molecule contraindications, see the molecule pages: Sermorelin, BPC-157, CJC-1295/Ipamorelin, PT-141, NAD+, AOD-9604.