Final answer:
A common complication in capillary sampling is the formation of a hematoma at the puncture site.
Step-by-step explanation:
A common complication in capillary sampling is the risk of hematoma formation at the puncture site. Hematoma is a localized collection of blood outside the blood vessels, resulting from bleeding due to injury. During capillary sampling, if the puncture is too deep or the puncture site is not properly compressed after sampling, it can lead to bleeding and the formation of a hematoma.