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Your guide to 31G pen needles and syringes

31G identifies the needle diameter. This independent reference explains dimensions, sterile single-use handling, packaging, and manufacturer instructions so readers can compare specifications accurately.

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Recent articles

Practical, source-cited writing on 31G pen needles and syringes — from the team that ships them across the EU.

Subcutaneous Injection Sites: Abdomen, Thigh, Upper Arm Explained

Subcutaneous injection

Subcutaneous Injection Sites: Abdomen, Thigh, Upper Arm Explained

The three subcutaneous injection sites — abdomen, outer thigh, upper arm — compared on absorption speed, comfort, ease of self-injection, and lipohypertrophy risk.…

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GLP-1 Needle and Syringe Sizing Guide: Mounjaro, Ozempic, Wegovy and Compounded Vials

Glp 1

GLP-1 Needle and Syringe Sizing Guide: Mounjaro, Ozempic, Wegovy and Compounded Vials

Mounjaro, Wegovy and Ozempic needle and syringe sizes — practical UK guidance on gauge, length and travel kit options for GLP-1 self-injection.

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4 mm vs 5 mm vs 6 mm Pen Needles for GLP-1 Injections: What the Evidence Says

Glp 1

4 mm vs 5 mm vs 6 mm Pen Needles for GLP-1 Injections: What the Evidence Says

4 mm is the modern default for GLP-1 self-injection. 5 mm is fine. 6 mm and 8 mm are mostly leftover diabetes-era stock. Here's what the FITTER consensus and EMA…

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How to Inject Mounjaro: an 8-Step Protocol from the KwikPen Instructions

Mounjaro

How to Inject Mounjaro: an 8-Step Protocol from the KwikPen Instructions

Step-by-step Mounjaro KwikPen injection protocol from the Eli Lilly user manual, with the bits where first-time UK users actually get stuck.

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Mounjaro KwikPen Needles: a UK Buyer's Guide for 4 mm and 5 mm Pen Needles

Mounjaro

Mounjaro KwikPen Needles: a UK Buyer's Guide for 4 mm and 5 mm Pen Needles

What pen needles fit the Mounjaro KwikPen, what UK pharmacies actually charge, and what Lilly's instructions require. 4 mm × 31G or 32G is the modern default.

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Rotating Injection Sites for Weekly GLP-1 Medications: a 4-Week Pattern

Glp 1

Rotating Injection Sites for Weekly GLP-1 Medications: a 4-Week Pattern

Lipohypertrophy is rare on weekly GLP-1 injection but not zero. Here's a simple 4-week abdomen-and-thigh rotation pattern, with the FITTER guidance behind it.

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Imogen Whitcombe — Editor

Imogen Whitcombe

Editor · 31-g.com

Who writes here

31-g.com is an independent information site about 31G sterile supplies. Articles are reviewed against manufacturer instructions before publication.

See our editorial policy for our review standards.

place EU-based verified Sterile-syringe supplier edit_note Independent editorial link Sources in every article

Frequently asked questions

Everything you want to know before ordering.

Is 31G the right gauge for me? expand_more

31 gauge is the thinnest precision needle commercially available — ideal for precision home-care with minimal discomfort. If your prescription specifies a different gauge, follow your doctor’s advice. For 29G or 30G, visit our sister sites 29-g.com or 30-g.com.

How fast will my order arrive? expand_more

Orders ship from Spain and arrive in 2-3 business days to most EU countries. Tracking number arrives by email as soon as your parcel is dispatched.

How is the package labelled? expand_more

Plain padded envelope. Sender appears as meeco SL with no product names, health terms, or brand markings on the outside. Only you will know what is inside.

What is your return policy? expand_more

Unopened, sealed packaging can be returned within 14 days of delivery for a full refund. For hygiene reasons we cannot accept returns of opened packages. Email info@31-g.com to start a return.

Is this a medical device? expand_more

Yes. Our syringes are high-quality medical supplies manufactured under ISO 13485. They are sterilised with ethylene oxide and supplied in sterile sleeves of 10. Each batch is traceable to its manufacturing facility.

Do you ship outside the EU? expand_more

Yes. We ship to all EU member states plus Switzerland, Norway, and the United Kingdom. Delivery times outside the EU may be slightly longer (3–7 business days) and import duties may apply.