The proper way to open a glass ampule is to 'score' them around the narrowest part of
their neck. To 'score' a glass ampule it is best to use a metal knife with small teeth. Occasionally, these are provided with the ampule and these knives work best. If these knives are not provided, it occasionally works to use a fingernail file, grapefruit knife, or a type of kitchen knife with very small teeth. This knife should be rotated around the narrow part of the neck in a sawing motion. After a white line or 'score' is clearly evident on the neck, the ampule is ready to be cracked open.

Before cracking the ampule open, it should be placed inside a clean paper towel or a thin clean cotton towel with one hand should firmly grasping the lower portion of the ampule. Your other hand should grasp the very top of the ampule.

A quick snapping motion should cleanly remove the top of the ampule. A needle can then be inserted and the liquid drawn out. Do not try to crack open an ampule without scoring it, or by using your fingers directly against the glass ampule. Occasionally the glass ampule can shatter and this glass can cause a serious cut.