Injections:
Sites, Technique, Reconstitution, Storage

The technique side of injections looks like a solved problem, until you're on month four and starting to develop scar tissue at the same two abdominal sites you've been using since day one. This page is the cross-cut for the technique, sites, reconstitution, and storage questions that come up across all three protocols.

For full context, the pillar pages cover the protocol-specific dosing decisions:

• TRT pillar, dosing, schedule, and SubQ vs IM
• GLP-1 pillar, choosing a compound and titration
• Peptides pillar, category-specific protocols

For walkthroughs of injection technique with photos and exact angle/needle guidance, see TRT injection guide, TRT walkthrough, and peptide guide.

Site rotation is the durable injection skill. The standard cross-protocol map:

The rule that matters: never hit the same exact site twice within a 7-day window, regardless of dose frequency. "The same site" means the same square inch, moving an inch up or left counts as rotation, but the abdominal grid only has so much real estate, which is why most users add at least one off-abdomen site within month two.

Peptide reconstitution is the source of most dose errors. The math:

Dose (units on U-100 syringe) = (target dose mcg / vial size mcg) × BAC water added (mL) × 100

Worked example: 5 mg vial of BPC-157, target 250 mcg per dose, reconstituted with 2 mL BAC water.

• Concentration: 5000 mcg / 2 mL = 2500 mcg/mL
• Per dose: 250 mcg / 2500 mcg/mL = 0.1 mL = 10 units

The error mode: someone uses 1 mL instead of 2 mL of BAC water. Same vial, same target, but now 10 units delivers 500 mcg. Dose math should be re-done from the BAC water added, not assumed from the last vial.

For an interactive calculator that handles every common vial size, see peptide calculator.

The articles below are the deep-dives that informed this hub, grouped by primary pillar. Each one expands on a specific question from the sections above.

From the TRT pillar

• First Trt Injection What To Expect
• Testosterone Cypionate Dosage Guide, Calculator & Dosing Charts, Free testosterone cypionate dosage calculator with dosing charts for 200mg/mL and 100mg/mL concentrations. Calculate exact syringe units for weekly, split, and daily microdosing protocols. SubQ vs IM comparison, side effect management, and common dosing mistakes.
• TRT Injection Schedule: Weekly vs Twice Weekly vs Daily Guide, Complete TRT injection schedule guide. Compare weekly, twice-weekly, EOD, and daily microdosing protocols. Includes frequency comparison table, week-by-week timeline, bloodwork timing, SHBG factors, SubQ vs IM by frequency, and switching protocols.

From the GLP-1 pillar

• BPC-157 Nasal Spray Dosage Guide, BPC-157 nasal spray dosing, preparation, and comparison to subcutaneous injection. Covers protocols, bioavailability differences, spray count by concentration, cycle length, and common mistakes. ## Localized Comparison Articles - /de/blog/retatrutid-vs-tirzepatid, Retatrutid vs Tirzepatid: Phase-3-Daten, Wirkmechanismus, Nebenwirkungen, Kosten (German) - /pt/blog/retatrutida-vs-tirzepatida, Retatrutida vs tirzepatida: dados de Fase 3, mecanismo de acao, efeitos colaterais, custos (Portuguese) - /es/blog/retatrutida-vs-tirzepatida, Retatrutida vs tirzepatida: datos de Fase 3, mecanismo de accion, efectos secundarios, costos (Spanish) - /fr/blog/retatrutide-vs-tirzepatide, Comparaison retatrutide vs tirzepatide : donnees de Phase 3, mecanisme d'action, effets secondaires, cout (French) - /de/blog/semaglutid-vs-tirzepatid-vs-retatrutid, Semaglutid vs Tirzepatid vs Retatrutid: Welche Abnehmspritze? Gewichtsverlust, Kosten, Nebenwirkungen (German) - /pt/blog/semaglutida-vs-tirzepatida-vs-retatrutida, Semaglutida vs tirzepatida vs retatrutida: qual escolher? Perda de peso, custos, efeitos colaterais (Portuguese) - /es/blog/semaglutida-vs-tirzepatida-vs-retatrutida, Semaglutida vs tirzepatida vs retatrutida: cual inyeccion elegir? Perdida de peso, costos, efectos (Spanish) - /fr/blog/semaglutide-vs-tirzepatide-vs-retatrutide, Comparaison complete des trois medicaments GLP-1 : semaglutide, tirzepatide et retatrutide (French) ## Social Media - X (Twitter): https://x.com/regimenapp - Instagram: https://www.instagram.com/helloregimen/ - TikTok: https://www.tiktok.com/@regimenapp ## Contact Email: support@helloregimen.com Website: https://helloregimen.com ## Dutch (NL) Localized Pages - /nl/, Dutch homepage with all trackers, calculators, and guides - /nl/trt-dosiscalculator, TRT dose calculator (Dutch) - /nl/peptide-reconstitutiecalculator, Peptide reconstitution calculator (Dutch) - /nl/glp1-dosiscalculator, GLP-1 dose calculator (Dutch) - /nl/tirzepatide-tracker, Tirzepatide (Mounjaro/Zepbound) tracker (Dutch) - /nl/bpc-157-tracker, BPC-157 peptide tracker (Dutch) - /nl/testosteron-tracker, Testosterone tracker (Dutch) - /nl/ozempic-tracker, Ozempic tracker (Dutch) - /nl/wegovy-tracker, Wegovy tracker (Dutch) - /nl/mounjaro-tracker, Mounjaro tracker (Dutch) - /nl/retatrutide-vs-tirzepatide, Retatrutide vs Tirzepatide comparison (Dutch) ## Spanish (ES) Calculator Pages - /es/calculadora-nasal, Intranasal peptide spray dose calculator (Spanish) - /es/calculadora-testosterona, Free and bioavailable testosterone calculator (Spanish) - /es/calculadora-dosis-dividida, Split dose calculator for TRT (Spanish) - /es/visualizador-vida-media, Half-life visualizer with PK curves (Spanish) - /es/calculadora-reconstitucion, Peptide reconstitution calculator (Spanish) ## German (DE) Calculator Pages - /de/intranasaler-rechner, Intranasal peptide spray dose calculator (German) - /de/testosteron-rechner, Free and bioavailable testosterone calculator (German) - /de/split-dosis-rechner, Split dose calculator for TRT (German) - /de/halbwertszeit-visualisierer, Half-life visualizer with PK curves (German) - /de/rekonstitutions-rechner, Peptide reconstitution calculator (German) ## Portuguese (PT-BR) Calculator Pages - /pt/calculadora-nasal, Intranasal peptide spray dose calculator (Brazilian Portuguese) - /pt/calculadora-testosterona, Free and bioavailable testosterone calculator (Brazilian Portuguese) - /pt/calculadora-dose-fracionada, Split dose calculator for TRT (Brazilian Portuguese) - /pt/visualizador-meia-vida, Half-life visualizer with PK curves (Brazilian Portuguese) - /pt/calculadora-reconstituicao, Peptide reconstitution calculator (Brazilian Portuguese) ## Localized Retatrutide Articles (DE, PT, ES, FR) - /de/blog/retatrutid-dosierung-anleitung, Retatrutid Dosierungsleitfaden: Titrationsschema, Split-Dosierung, Mikrodosierung (German) - /pt/blog/retatrutida-dosagem-guia, Guia de dosagem de retatrutida: titracao, dose fracionada, microdosagem (Portuguese) - /es/blog/retatrutida-dosificacion-guia, Guia de dosificacion de retatrutida: titracion, dosis dividida, microdosis (Spanish) - /fr/blog/retatrutide-dosage-guide, Guide de dosage du retatrutide : titration, dose fractionnee, microdosage (French) - /de/blog/retatrutid-nebenwirkungen-leitfaden, Retatrutid Nebenwirkungen: Woche-fur-Woche Timeline nach Dosisstufe (German) - /pt/blog/retatrutida-efeitos-colaterais-guia, Efeitos colaterais da retatrutida: timeline semana a semana por dose (Portuguese) - /es/blog/retatrutida-efectos-secundarios-guia, Efectos secundarios de retatrutida: timeline semana a semana por dosis (Spanish) - /fr/blog/retatrutide-effets-secondaires-guide, Effets secondaires du retatrutide : timeline semaine par semaine par dose (French) - /de/blog/wechsel-tirzepatid-zu-retatrutid, Wechsel von Tirzepatid zu Retatrutid: Protokoll und Dosisaquivalenz (German) - /pt/blog/troca-tirzepatida-para-retatrutida, Troca de tirzepatida para retatrutida: protocolo e equivalencia de doses (Portuguese) - /es/blog/cambio-tirzepatida-a-retatrutida, Cambio de tirzepatida a retatrutida: protocolo y equivalencia de dosis (Spanish) - /fr/blog/transition-tirzepatide-vers-retatrutide, Transition du tirzepatide au retatrutide : protocole et equivalence des doses (French)
• Peptide Injection Sites: SubQ Rotation Map and Technique Tips, The 6 best subcutaneous injection sites for peptides, GLP-1s, and TRT. How to build a rotation pattern, injection technique tips, and when to skip a site.
• How to Reconstitute Peptides: BAC Water Calculator + Dosing Chart, Step-by-step peptide reconstitution with free calculator. How much bacteriostatic water for BPC-157, semaglutide, and tirzepatide vials, plus syringe unit conversion chart.
• Peptide Storage Guide: How to Store Reconstituted Peptides, Lyophilized vs reconstituted storage, temperature requirements, the 28-day rule, BAC water shelf life, GLP-1 pen storage windows, travel tips, signs of degradation, and common storage mistakes.
• Retatrutide Reconstitution Calculator Guide, How to reconstitute compounded retatrutide with bacteriostatic water, including a free dose calculator for 5mg, 12mg, and 30mg vials. Step-by-step mixing guide, dose charts, titration schedule, and triple-agonist comparison with semaglutide and tirzepatide.
• Semaglutide Reconstitution Calculator Guide, How to reconstitute compounded semaglutide with bacteriostatic water, including a free dose calculator, step-by-step instructions, and storage guidelines.
• Tirzepatide Reconstitution Calculator Guide, How to reconstitute compounded tirzepatide with bacteriostatic water, including a free dose calculator, dose escalation schedules, and storage guidelines.
• Traveling with Peptides & GLP-1 Meds: TSA Rules, Cold Chain Storage, and Packing Checklist, TSA rules for flying with peptide vials, GLP-1 pens (Ozempic, Mounjaro), and TRT. Cold chain storage for reconstituted peptides, room-temp windows for branded pens, international regulations, and a complete packing checklist.

From the Peptides pillar

• BPC-157 Reconstitution Calculator Guide, How to reconstitute BPC-157 peptide with bacteriostatic water, including a free dose calculator, common dosing protocols, and storage instructions.
• How to Make a Peptide Nasal Spray, Step-by-step guide to making a peptide nasal spray at home. Covers supplies, reconstitution, concentration math, transfer to spray bottle, storage, and common mistakes.
• Peptide Blend Dosing: How to Calculate Per-Peptide Doses in Multi-Compound Vials, How blend ratio math works for pre-mixed peptide vials (GLOW, KLOW, Wolverine, CJC-1295/Ipamorelin). Reconstitution for multi-peptide vials, worked examples with exact syringe units, safety warning against DIY peptide mixing, and common mistakes.
• Peptide Injection Schedule Beginners
• The Peptide Starter Kit: Everything You Need Before Your First Injection, Complete supply checklist, reconstitution basics, injection technique, and storage rules for your first peptide protocol.
• Tb500 Reconstitution Dosing Guide

OptiPin's injection-site rotation map advances automatically across the six SubQ and IM sites as you log doses, so the next-shot site is always one tap away. The reconstitution calculator is built in, pick the vial, enter BAC water added, set target dose, and the syringe-unit number is computed and stored against the active vial. Vial inventory tracks open dates and discard windows per compound (28 days for most GLP-1s, 30 days for most reconstituted GH peptides), with reorder reminders firing before you run out. For users on multiple compounds, the inventory view is the difference between a calm Friday refill and a frantic Sunday-night reconstitution at the wrong concentration.