When to Stop

• Allergic reaction. As with any injectable peptide, theoretical anaphylaxis risk on first administration. No published cases for ARA-290 specifically — the molecule is small (1257 Da) and non-glycosylated, so immunogenicity is expected to be low — but: first 30 minutes of injection #1 should be at home, with antihistamine accessible.
• Off-target erythropoietic effect. This is the theoretical risk that the IRR-selectivity premise is what's keeping ARA-290 safe — and it has been validated across 15+ years of trial work without a hematocrit, hemoglobin, or reticulocyte count signal in published cohorts. However, the long-term risk of "what if at extended use or higher doses some EPOR-homodimer activation creeps in" is not zero. Practical safety check: monitor CBC + hematocrit before and after cycle. If hematocrit rises, that flags off-target activity and the protocol should stop. This is a key biomarker safeguard for ARA-290 specifically.
• Theoretical thrombosis risk if erythropoietic activity emerges. EPO's most serious adverse effect is increased thromboembolic risk via raised hematocrit — ARA-290's safety thesis is that it never raises hematocrit, therefore never raises thrombosis risk. Validated to date but worth flagging the chain of inference.
• Theoretical immune dysregulation. ARA-290 modulates innate immune signaling (M2 polarization, anti-inflammatory cytokine output). Chronic immune-axis modulation in healthy users is theoretically suboptimal. No published case reports of clinically meaningful immune suppression at trial doses.
• Day 1 + first 30 min of every cycle initiation: anaphylaxis window. Inject at home, antihistamine within reach.
• Pre-cycle CBC baseline + week 4 CBC follow-up: Hematocrit must NOT rise. This is the critical safety check distinguishing ARA-290 from EPO. Pre-cycle hsCRP also reasonable (would expect mild reduction on cycle as anti-inflammatory marker).
• Throughout cycle: any unusual headache pattern, especially with elevated blood pressure, would flag potential off-target erythropoietic effect — stop and re-baseline CBC.
• Lifetime cumulative load: if running multiple cycles per year, periodic CBC + reticulocyte count + blood-pressure checks are reasonable due-diligence. Reasonable cap: 2 cycles per year for chronic management.
• Active erythrocytosis or polycythemia (theoretical concern that any residual EPOR-homodimer activity would compound the existing condition)
• Active malignancy (general peptide caution; theoretical IRR signaling at tumor sites)
• Recent thromboembolic event
• Pregnancy / lactation (no human data)
• Severe renal or hepatic impairment (clearance not characterized in detail)
• Known peptide hypersensitivity