How to self-inject intramuscular vitamin B12

This information is for patients who are being treated for nerve problems related to the use of nitrous oxide, also known as ‘laughing gas’ or ‘whippets’. 

The initial treatment involves daily intramuscular (into the muscle) vitamin B12 injections. For convenience, these injections can be safely given by the patient themselves at home.

Below are the step-by-step instructions that show how to self-inject the vitamin B12 safely. The pictures will help you to understand how to do this. 

What you will need

You will be provided with the equipment to self administer your B12 injection: 

  • 2ml syringe
  • Injecting needle. This will be either blue or green. A green needle might be provided if you require a longer needle to inject into the muscle bulk. 
  • Glass capsule (ampoule) of vitamin B12
  • Purple needle for drawing up B12 
  • Cleaning wipes (containing alcohol) 
  • Clean gauze or cotton wool 
  • Sharps bin



Step 1

Wash your hands with soap and warm water.

Place all of the equipment on a clean, flat surface. 

Opening the ampoule of vitamin B12

Step 1 

Tap the top of the B12 ampoule with your finger, so that the solution flows to the bottom. 

Step 2

Remove a cleaning wipe from the packet and unfold it fully. Use it to wipe the top of the ampoule in a circular motion. Leave it to air-dry for 30 seconds.

Step 3

Hold the base of the ampoule in your non-dominant hand. If you’re right handed this will be your left hand. If you’re left handed, this will be your right hand. 

Using the same cleaning wipe, grab the top of the ampoule between your thumb and forefinger in your dominant hand.

Make sure the black dot is facing towards you, and that you snap the lid away from you.

Snap the top off by applying pressure at the black dot on the base of the lid. 

Drawing up B12 from the open ampoule

Step 1 

Remove the purple drawing needle out of the packet. Secure it onto the end of your syringe.  

Step 2 

Remove the red cap from the purple drawing needle. 

Step 3

Place the tip of the drawing needle in the bottom of the ampoule. Pull the syringe plunger, until all the fluid is in the syringe (1ml total). 


Step 4

Hold the syringe pointing upwards. Tap the syringe with your finger to remove any air bubbles. 

Slowly push the plunger upwards to remove the air from the syringe. Do this until the fluid reaches the tip of the syringe. 

Step 5 

Remove the needle from the syringe, and dispose of it in the sharps bin. 

Placing the injecting needle on the filled syringe

Step 1

Open the blue injecting needle and secure it on the end of your syringe full of b12. 

You might be given a green injecting needle to use, instead of a blue one. 

Step 2 

Remove the protective cap. Pull the pink safety cover back to expose the needle. 

Locate the injection site 

The injection site will be about halfway down the outer part of your thigh. 

A good way to find the right spot is to rest the palm of your hand on your hip bone.

The injection point should be where your fingers end.

The area to safely inject is shown by the shading in the photograph.


Giving the injection

Step 1

While comfortably sat down, remove a new cleaning wipe from its packaging, and unfold it.

Clean the skin over the injection site by rubbing the cleaning wipe in circular motions.

Leave to air-dry for 30 seconds.

Alcohol can sting so you must wait for it to dry or it will make the injection more painful.

Step 2

Stretch the skin taught over your injection site and make sure your muscle is relaxed.


Step 3 

Make sure the needle is placed at a 90 degree angle to the skin. Insert the needle, so that only half the needle has gone into your skin.

Step 4

Slowly pull back on the syringe plunger first to check you are not within a blood vessel. If the syringe fills with blood, remove the needle and start again at site a few centimetres further down your leg. If you’re unable to pull the syringe plunger back (the syringe does not fill with blood) then proceed with pushing the plunger down slowly over 5 to 10 seconds. Slower injections are less painful.

Step 4

Remove the needle. If you are bleeding, press the area gently with some clean gauze or cotton wool.

Step 5

Cover the needle with the pink safety cover by pressing on a firm surface until you hear a click. 

Step 6 

Dispose of the needle in the sharps bin. 

Safe disposal of equipment

It is important that you dispose of all the equipment when you have finished. 

Some of your equipment will need to be disposed of in the sharps bin, and the rest can be disposed of in your household rubbish. 

Equipment to be disposed of in sharps bin:

  • Injecting needle
  • Empty glass ampoule
  • Purple needle used to draw up medicine

Equipment to be disposed of in household rubbish:

  • Syringe 
  • Cleaning wipes
  • Packaging

Sharps bin

Close the lid on your sharps bin after each use. Gently press the lid down. Do not push too hard as this will lock the lid.

Dispose of a full sharps bin by taking it to your local pharmacy or by contacting the local council for specialist disposal. Do not dispose in your household waste.


  • Store unused equipment and medicine in a safe place, away from children and pets.
  • Store capsules of B12 at room temperature, not in the fridge.

More information

If you have a phobia of needles and need support, let the staff caring for you know.

You might find our information about needle phobia and overcoming your fear useful. 

Resource number: 5471/VER1
Last reviewed: February 2024 
Next review due: February 2027 

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