Which peptides work with a reusable peptide pen?
RefillPen is a reusable injection pen for standard 3 mL cartridges you fill yourself. It measures by volume, in units, so it isn’t tied to one peptide: retatrutide, semaglutide, tirzepatide, GHK-Cu, BPC-157, Glow blends and 67 label names in all. Here’s how compatibility works.
How peptide pen compatibility works
A RefillPen doesn’t come prefilled. You fill a standard 3 mL glass cartridge, load it into the pen, and dial your amount in units. The pen measures volume, not a specific compound: one click is one unit, one unit is 0.01 mL, and a full 3 mL cartridge holds 300 units. That is why one pen works with so many different peptides.
| Pen | Most per injection | Volume | Cap |
|---|---|---|---|
| V1 | 80 units | 0.80 mL | Closed cap, slim metal body |
| V2 | 60 units | 0.60 mL | Open cap, needle stays hidden |
| V2.5 Slim Hybrid | 60 units | 0.60 mL | Open cap, lighter slim body |
| V3 | 60 units | 0.60 mL | Closed cap, slim or regular metal body |
- Most per injection
- 80 units
- Volume
- 0.80 mL
- Cap
- Closed cap, slim metal body
- Most per injection
- 60 units
- Volume
- 0.60 mL
- Cap
- Open cap, needle stays hidden
- Most per injection
- 60 units
- Volume
- 0.60 mL
- Cap
- Open cap, lighter slim body
- Most per injection
- 60 units
- Volume
- 0.60 mL
- Cap
- Closed cap, slim or regular metal body
Every RefillPen takes standard 3 mL cartridges and universal screw-on pen needles.
Not sure how many units your amount works out to? The free peptide pen dosage calculator does the math, and the Best Reusable Peptide Pen guide compares the four models in more detail.
Prefilled peptide pens vs a reusable RefillPen
Many “peptide pens” sold online come prefilled by the seller and are thrown away when empty. RefillPen is the reusable alternative: we sell the pen, the cartridges and the accessories, never peptides. You load a 3 mL cartridge, and when it runs out you load a fresh $1 cartridge and keep the pen.
| Prefilled pen | RefillPen | |
|---|---|---|
| Comes filled? | Yes, by the seller | No, you fill a standard 3 mL cartridge |
| When it’s empty | Usually thrown away | Load a new $1 cartridge and keep the pen |
| Dose dial | Varies by maker | One click = one unit, up to 60 or 80 units |
| Works with other peptides? | Only what it was filled with | Whatever you load in a 3 mL cartridge |
Comes filled?
- Prefilled pen
- Yes, by the seller
- RefillPen
- No, you fill a standard 3 mL cartridge
When it’s empty
- Prefilled pen
- Usually thrown away
- RefillPen
- Load a new $1 cartridge and keep the pen
Dose dial
- Prefilled pen
- Varies by maker
- RefillPen
- One click = one unit, up to 60 or 80 units
Works with other peptides?
- Prefilled pen
- Only what it was filled with
- RefillPen
- Whatever you load in a 3 mL cartridge
Retatrutide, semaglutide and tirzepatide pens
Retatrutide, semaglutide and tirzepatide all work in a RefillPen the same way: fill a 3 mL cartridge, load it, prime, and dial your units. We make pen labels for Retatrutide (Reta), Semaglutide (Sema), Tirzepatide (Tirz), Cagrilintide (Cagri), Survodutide and Eloralintide, so a pen for each is easy to tell apart.
Glow, Klow and Wolverine blend pens
Blends go in a cartridge like any single peptide. Glow is a blend of GHK-Cu, BPC-157 and TB-500, Klow adds KPV to the same three, and Wolverine is BPC-157 with TB-500. Load the blend’s cartridge, prime, and dial in units as usual. We make Glow, Klow and Wolverine labels.
GHK-Cu, BPC-157 and TB-500 pens
GHK-Cu, BPC-157 and TB-500 work in a RefillPen the same way, one peptide per cartridge. We make labels for GHK-Cu, GHK Basic, BPC-157, TB-500 and TB Frag, plus KPV and LL-37.
Tesamorelin, ipamorelin, CJC-1295 and sermorelin pens
Tesamorelin, Ipamorelin, CJC-1295, Ipamorelin/CJC, Sermorelin, HGH, HCG, IGF-1 and Kisspeptin all have RefillPen labels, and each goes in its own 3 mL cartridge in the same pen.
NAD+, MOTS-c and other peptides
NAD+, MOTS-c, SS-31, Humanin, Epitalon, Pinealon, Selank, Semax and the rest of the names below all load the same way. If it’s in a standard 3 mL cartridge, the pen dials it in units.
Every peptide name we make pen labels for
If you run more than one peptide, our slide-on peptide pen labels ($0.99 each) fit around the pen and name what’s inside. No adhesive, so there’s no sticky residue. We currently make labels for 67 names:
- 5-Amino-1MQ
- Adalank
- Adamax
- AICAR
- AOD-9604
- ARA-290
- BPC-157
- Cagrilintide (Cagri)
- Cartalax
- Cerebrolysin
- CJC-1295
- DSIP
- Eloralintide
- Epitalon
- FOXO4
- GCA Bluetide
- GCA Deeptide
- GCA Hightid3
- GCA Metatide
- GCA Riptid3
- GHK Basic
- GHK-Cu
- Glow
- Glutathione
- HCG
- HGH
- HSN (Hair/Skin/Nails)
- Humanin
- IGF-1
- Illumineuro
- Ipamorelin
- Ipamorelin/CJC
- Kisspeptin
- Klow
- KPV
- L-Carnitine
- Lipo C
- LL-37
- Magic Sleep
- Melanotan 1
- Melanotan 2
- MIC B
- Mitoprime
- MOTS-c
- NAD+
- Oxytocin
- PE-22-28
- Pinealon
- PT-141
- Retatrutide (Reta)
- Selank
- Semaglutide (Sema)
- Semax
- Sermorelin
- Shred
- SS-31
- Super Human
- Survodutide
- TB Frag
- TB-500
- Tesamorelin
- Thymosin
- Tirzepatide (Tirz)
- Vesilute
- VIP
- Vitamin D3
- Wolverine
One pen per peptide, or one pen for several?
Both work. Pick whichever fits how you use your pens:
- One pen per peptide: the simplest way to never mix them up. Name each pen with a label and give it its own colored Halo cartridge holder.
- One pen, swapped cartridges: keep each peptide in its own labeled cartridge and swap it in when you need it. Re-prime every time you swap; this short video shows how.
Either way, keep one peptide (or one blend) per cartridge, so the label always matches what’s inside.
What you need to get started
- A pen: the V1, V2, V2.5 or V3. Every pen comes with an empty 3 mL cartridge.
- Spare cartridges: individually packed 3 mL glass cartridges, $1 each.
- Universal pen needles: the standard screw-on kind; see the FAQ for sizes.
- Labels and holders: peptide pen labels and Halo cartridge holders to tell pens apart.
- Somewhere to keep it: a vial travel box or pen stand.
Or put it all together in one go with the Starter Kit builder.
Peptide pen compatibility questions
Can I use a RefillPen with tirzepatide or semaglutide?
Yes. RefillPen is a reusable pen for standard 3 mL cartridges you fill yourself. It measures in units and isn’t built for any single compound, and we make pen labels for tirzepatide (Tirz) and semaglutide (Sema). RefillPen is not a prefilled pen and isn’t affiliated with any drug brand.
Can I use a RefillPen for retatrutide?
Yes. Load retatrutide in a standard 3 mL cartridge, prime, and dial in units like any other peptide. We make Reta labels, including a limited-edition Pink Lemonade color.
Can I use a RefillPen for BPC-157, TB-500, GHK-Cu or NAD+?
Yes. The pen works the same way whatever the cartridge holds: fill a standard 3 mL cartridge, load it, prime, and dial in units. We make labels for all four, and for 63 other names listed above.
Can I put Glow, Klow or Wolverine blends in a RefillPen?
Yes. A blend goes in one cartridge just like a single peptide, and we make Glow, Klow and Wolverine labels so the pen says which blend is inside.
Does RefillPen sell peptides or prefilled pens?
No. RefillPen sells the pens, 3 mL cartridges and accessories, not peptides. Every pen comes with an empty 3 mL cartridge, ready for you to fill.
Can I use one pen for different peptides?
Yes. You can swap cartridges in and out of one pen; just re-prime each time you swap. Or keep one pen per peptide and tell them apart with pen labels and colored Halo cartridge holders.
How many units are in a 3 mL cartridge?
300. One click is one unit, and one unit is 0.01 mL, so a full 3 mL cartridge holds 300 units. How many doses that gives depends on your dose size; the peptide pen dosage calculator works it out.
Is a RefillPen the same as a reusable insulin pen?
It works the same way: a mechanical pen with a dose dial that takes standard 3 mL cartridges and screw-on pen needles, with no batteries. RefillPen is made and sold for peptides, in four models and 50 color combinations.
How should I store and travel with a loaded pen?
Never leave a pen or cartridges in a car, even covered: it can pass 86 °F within minutes. When flying, keep the pen and supplies in your carry-on, because a checked bag’s hold can freeze. Take the needle off after every use. The FAQ covers storage and travel in more detail.
Do you ship RefillPen to the UK?
Yes. We ship internationally by USPS, including to the United Kingdom, at a flat rate shown in your cart. See Shipping & Delivery for every country.
Which reusable peptide pen should I choose?
Choose the V1 if you need the widest range (up to 80 units), the V3 for a solid metal closed-cap pen, or the V2.5 Slim Hybrid for a lighter body that keeps the needle hidden. The Best Reusable Peptide Pen guide compares them side by side.
For research purposes only.
Ready to get started?
Reusable peptide pens from $24.99, $1 sterilized cartridges, and free shipping on orders over $59.
Or try the free peptide pen dosage calculator →