🚫 Warning: This is not a complete medical contraindications list. It is a reference for common situations where the risk-benefit balance is clearly unfavourable. When in doubt, consult a doctor.
1. Absolute contraindications — do not use
| Condition / situation | Compounds affected | Reasoning |
|---|---|---|
| Active cancer (any type) | All GH-axis peptides, IGF-1-raising compounds | GH and IGF-1 are mitogenic — they promote cellular proliferation. This can accelerate tumour growth. |
| History of cancer (within 5 years or hormone-sensitive) | GH secretagogues, IGF-1-raising compounds | Risk of promoting residual or occult tumour cells. |
| Pregnancy | All research peptides | No foetal safety data. Unknown teratogenic risk. |
| Breastfeeding | All research peptides | Transfer to breast milk unstudied. Infant exposure risk unknown. |
| Known hypersensitivity/allergy to a compound | The specific compound | Potential for severe allergic reaction including anaphylaxis. |
| Acromegaly or gigantism | All GH-axis peptides | These conditions involve excess GH — further stimulation is directly harmful. |
| Active diabetic retinopathy | GH secretagogues | GH elevation worsens retinal vessel disease. |
2. Relative contraindications — use with caution or avoid
| Condition | Concern | Guidance |
|---|---|---|
| Type 1 diabetes | GH secretagogues worsen insulin resistance | Avoid GH-axis peptides or use only under close medical supervision with tight glucose monitoring. |
| Type 2 diabetes (poorly controlled) | Same as above | GLP-1 agonists may be beneficial; GH secretagogues require caution. |
| Carpal tunnel syndrome | GH elevation causes fluid-related nerve compression | GH-axis peptides may worsen symptoms. Monitor closely. |
| Benign prostatic hyperplasia (BPH) | GH and androgens stimulate prostate tissue growth | Males with BPH should monitor PSA if using GH secretagogues. |
| Active autoimmune disease | Immune-modulating peptides can alter immune balance | TB-500, Thymosin Alpha-1, LL-37 may unpredictably affect autoimmune conditions. |
| Severe kidney disease (eGFR <30) | Impaired clearance | Dose adjustments needed; increased accumulation risk. Medical oversight required. |
| Active mental health crisis | Some peptides (Semax) have stimulating effects; PT-141 has mood effects | Not contraindicated generally, but introduce carefully. |
3. Drug interactions
| Drug | Peptide interaction |
|---|---|
| Insulin (exogenous) | GH secretagogues oppose insulin action — blood glucose may rise unpredictably |
| Sulfonylureas / SGLT-2 inhibitors | As above — blood glucose monitoring essential with any GH-axis peptide |
| Warfarin | Some peptides may have mild antiplatelet effects — INR monitoring recommended |
| Immunosuppressants (tacrolimus, cyclosporine) | Immune-modulating peptides may counteract immunosuppression post-transplant |
| SSRIs / SNRIs / MAOIs | PT-141 (bremelanotide) — serotonin interactions; avoid with serotonergic drugs |
| Corticosteroids (systemic) | GH secretagogues: corticosteroids blunt GH release; reduces effectiveness |
| Thyroid hormone replacement | GH elevation alters T4→T3 conversion; thyroid medication may need adjustment |
| Chemotherapy agents | GH-axis peptides: avoid — potential to promote cancer cell growth |
4. Life stage considerations
| Life stage | Considerations |
|---|---|
| Under 18 | GH axis is naturally active during adolescence — exogenous stimulation via GH secretagogues is not appropriate and may disrupt normal growth patterns. |
| 18–25 | GH pulsatility is still relatively high naturally. GH secretagogues offer less incremental benefit than in older adults; risk-benefit calculation is less favourable. |
| 25–45 | Standard research population. Risk-benefit is most favourable for most peptides. |
| 45+ | GH secretagogues have clearer benefit as natural GH decline accelerates. Monitor PSA (males) and IGF-1 actively. |
| Post-menopause | Hormonal context changes. Some peptides interact with oestrogen pathways. PT-141 mechanism is preserved. Discuss with doctor if on HRT. |
| Elite athletes (competitive) | WADA considerations apply. Many GH-axis and GLP-1 peptides are banned. Career-ending if detected. |