Final answer:
Apply a warm compress to the puncture site to encourage blood flow. If this is ineffective, massage the area or consider repeating the puncture at a different site with a new lancet.
Step-by-step explanation:
If a drop of blood does not form after capillary puncture, the most suitable actions to take can depend on the situation and the reason why the blood is not forming. However, oftentimes, the first intervention would be to encourage blood flow to the area, which can be done by warming the site. Applying a warm compress to the site can help increase blood flow. If this does not work, or if the warm compress is not available, massaging the area from the base of the finger towards the puncture site can also stimulate blood flow. One should ensure that the puncture was deep enough and, if necessary and following proper procedures, consider repeating the puncture at a different site using a new lancet. It is important to not squeeze the fingertip too hard as it might cause tissue fluid to mix with blood, which can affect test results.