Which of the following is a common complication of venipuncture?

Hematoma is indeed a common complication of venipuncture. When a needle is inserted into a vein for the purpose of drawing blood or administering medication, there is a risk that the needle may puncture both walls of the vein or cause the vessel to bleed into the surrounding tissue. This leads to the accumulation of blood outside the vessel, forming a hematoma, which is essentially a localized collection of blood.

Signs of a hematoma include swelling, tenderness, discoloration, and sometimes, a firm mass under the skin at the puncture site. While this condition is generally benign and can resolve on its own, it may cause discomfort and occasionally require treatment if it becomes significant or interferes with further venipuncture.

In contrast, the other options such as dehydration, coughing, and headache are not direct complications associated with the venipuncture procedure itself. Dehydration is more about a patient's overall status before a procedure, coughing might occur due to unrelated respiratory issues, and headaches can arise from numerous other causes but do not typically result from the act of venipuncture. Therefore, hematoma stands out as the relevant and expected complication in this context.