NEW COAs JUST LANDED — 99% purity across every GLP-1 compound•Independently lab-tested by Analiza Bialek European testing•Third-party verified identity & purity — every compound, every time•The real deal. Traceable compound numbers. Downloadable certificates.•View the latest Certificates of Analysis →•NEW COAs JUST LANDED — 99% purity across every GLP-1 compound•Independently lab-tested by Analiza Bialek European testing•Third-party verified identity & purity — every compound, every time•The real deal. Traceable compound numbers. Downloadable certificates.•View the latest Certificates of Analysis →•
Peptides UK 4U
PEPTIDES UK 4U
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Reta Pen UK

Reta Pen UK — Pre-Filled Retatrutide Quick Pens (20mg / 30mg / 40mg)

A pre-filled Reta pen (Retatrutide research pen), reconstituted under controlled conditions in our UK facility and cold-shipped ready to use. No bacteriostatic water measuring, no mixing, no clicks guesswork — your V2 Quick Pen arrives calibrated and labelled.

  • Ready-mixed — no bac water needed
  • 99%+ HPLC tested Retatrutide
  • Clicks-per-mg card included
  • Cold-shipped, Royal Mail Tracked 24
  • Same-day dispatch before 1pm
  • Discreet, plain outer packaging

Prefer to mix your own? The same batch is available as Retatrutide vials UK from £89 (£3.85/mg) — the lowest cost per mg and full dosing flexibility. Background, trial evidence and legality are covered in the Retatrutide UK guide, and what “reta” means is explained on our reta peptide page.

For In Vitro Use Only — Not for Human Use. Not a licensed medicine in the UK.

Pen price (all-in)
from £123.99
UK stock
dispatched today
Retatrutide 20mg — Quick Pen
Pre-filled, ready-to-use dial-a-dose pen.
£123.99
vial + pen
Retatrutide 30mg — Quick Pen
Pre-filled, ready-to-use dial-a-dose pen.
£153.99
vial + pen
Retatrutide 40mg — Quick Pen
Pre-filled, ready-to-use dial-a-dose pen.
£188.99
vial + pen
Switch to a vial & save £34.99
Same batch, same COA — from £89.00 (£3.85/mg). Best value · same-day dispatch.
Buy Retatrutide Pen

Add 31G pen needles if you need a full pack.

Prefer to mix it yourself?

The same batch and COA in a plain vial costs less per mg — Retatrutide 20mg £89, 30mg £119, 40mg £154. See Retatrutide vials UK for strengths, cost per mg and reconstitution volumes, or buy direct on the Retatrutide product page.

Pay securely by card — no bank transfers, no waiting

  • Pay by cardVisa, Mastercard & Maestro
  • Instant confirmationOrder confirmed the moment you pay
  • Same-day dispatchOrder before 1pm, Mon–Fri
  • Encrypted checkoutNo card details stored by us

Retatrutide pen price in the UK

StrengthVial onlyQuick Pen (all-in)Refill cartridgeCost per mg
Retatrutide 20mg£89.00£123.99£101.99£4.45/mg
Retatrutide 30mg£119.00£153.99£131.99£3.97/mg
Retatrutide 40mg£154.00£188.99£166.99£3.85/mg

The Quick Pen adds £34.99 to the vial price and includes reconstitution, bacteriostatic water, the pen itself and a calibrated clicks-per-mg card. Already own a pen? A pre-filled replacement cartridge is £12.99 on top of the vial.

Reta Pen UK — how to use a Retatrutide pen

Select the Pen format above and we prepare your 20mg, 30mg or 40mg Retatrutide vial as a pre-filled, calibrated dial-a-dose Reta pen in the UK, cold-shipped with a clicks-per-mg card.

  1. Step 1
    Bring the pen to room temperature

    Take the pen out of the fridge 10–15 minutes before use. Cold solution is thicker and dispenses less accurately. Never microwave, warm in hot water or shake the pen.

  2. Step 2
    Inspect the cartridge

    Hold the pen up to the light. The reconstituted Retatrutide should be clear and colourless with no visible particles or cloudiness. If it looks off, stop and contact us.

  3. Step 3
    Attach a fresh needle

    Wipe the rubber septum with an alcohol swab, then screw on a new 31G 6mm pen needle. Always use a new needle each time — reused needles blunt, contaminate and cause dose loss.

  4. Step 4
    Prime the pen

    Dial 2 units, point the needle upwards and press the plunger until a droplet appears at the tip. Priming clears the air gap so your first dose is a full dose. Repeat if no droplet appears.

  5. Step 5
    Dial the dose in clicks

    Each click equals a fixed volume, and the mg-per-click depends on the vial strength and fill volume. Use the calibrated clicks-per-mg card in your box, or cross-check on our free reconstitution calculator.

  6. Step 6
    Dispense and hold

    Press the plunger fully and hold for 6–10 seconds before withdrawing so the full dialled volume is delivered rather than left in the needle.

  7. Step 7
    Remove the needle and refrigerate

    Unscrew and dispose of the needle in a sharps bin — never store the pen with a needle attached, as that lets solution leak and air enter. Return the pen to 2–8°C.

Reta pen FAQs (Retatrutide pens)

How do you use a Retatrutide pen?

Bring the pen to room temperature, attach a fresh 31G 6mm needle, prime with 2 units until a droplet appears, dial your dose in clicks using the calibrated card supplied, dispense and hold for 6–10 seconds, then remove the needle and refrigerate at 2–8°C.

Where can I buy a Reta pen in the UK?

Peptides UK 4U supplies Reta pens (Retatrutide pens) from our UK facility. Choose your strength (20mg, 30mg or 40mg) and select the Pen format on this page — we handle reconstitution and bacteriostatic water and cold-ship it ready to use.

How much is a Reta pen UK?

The Reta pen price is the vial price plus the Quick Pen preparation, shown as an all-in price when you select the Pen format on this page.

What is a Reta pen?

A Reta pen is a standard dial-a-dose injection pen pre-loaded with reconstituted Retatrutide, prepared in a controlled UK environment at a set concentration so the clicks-per-mg are calibrated before it reaches you. Reta is simply the common short-hand for Retatrutide.

How many clicks per mg on a Reta pen?

Clicks-per-mg vary with vial strength. A calibrated clicks-per-mg card is included with every Reta pen we dispatch, and you can cross-check any dose with our free online calculator.

How are Reta pens shipped in the UK?

Reta pens ship in insulated cold packaging via Royal Mail Tracked 24. Orders placed before 1pm on a working day are dispatched the same day from our UK premises.

How long does a Retatrutide pen last once opened?

Once reconstituted, Retatrutide should be refrigerated and is generally stable for around 4–6 weeks. Keep the pen at 2–8°C between uses and away from direct light.

Do I need needles for the Reta pen?

Yes — the pen uses standard screw-on pen needles. We recommend 31G 6mm needles and stock them on-site so you can add a pack at checkout.

Also researching Tirzepatide? See our Tirz pen guide and Tirzepatide vials UK and Semaglutide vials UK pricing page — 20mg, 40mg and 60mg, UK stock, same-day dispatch before 1pm.

Retatrutide 40mg pen UK

The Retatrutide 40mg pen is our largest pre-filled Quick Pen at £188.99 all-in — £3.85 per mg, the lowest cost per mg of any strength we fill. It is the same 99%+ HPLC-tested batch as the 20mg and 30mg pens, reconstituted and calibrated in our UK facility, and it runs roughly twice as long as a 20mg pen before a refill cartridge is needed. A pre-filled 40mg replacement cartridge for a pen you already own is £166.99.

Where to buy Retatrutide pens in the UK

Peptides UK 4U is a UK-based supplier — stock is held at our own premises, so there is no overseas transit and no customs delay. Choose the Pen format on the Retatrutide product page, order before 1pm Monday to Friday and it is cold-shipped the same working day by Royal Mail Tracked 24 in plain unbranded packaging. Every batch carries an openly published Certificate of Analysis, and card payments run through an encrypted 3-D Secure gateway.

Prefer vials?

The vial is the same peptide, same batch and same COA — £34.99 cheaper than the pen because you reconstitute it yourself. Our Retatrutide vials UK page has full pricing, cost per mg, bacteriostatic water volumes and syringe unit tables for the 20mg, 30mg and 40mg vials.

Related Retatrutide pages

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