What does it mean when cupping therapy draws out yellow fluid blisters?

After removing a cupping jar, if yellow blisters appear on the skin, this indicates that the cupping duration was too long and excessive negative pressure caused skin damage. During cupping, significant negative pressure is created inside the jar. Once the skin is drawn into the jar, the subcutaneous tissue fluid is affected by this pressure and migrates toward the area of higher negative pressure—namely, beneath the skin. If the cups are left in place too long, this fluid can accumulate under the skin and form blisters. Specific details are as follows:

In traditional Chinese medicine, cupping therapy is considered a process that helps expel toxins from within blisters out of the body. The essence of blister formation during cupping is essentially "fluid accumulation" beneath the skin. Pathological substances such as phlegm, dampness, and excess fluid are drawn to the surface via negative pressure, resulting in blister formation. After cupping, local skin may develop blisters; besides phenomena such as bleeding or bruising, some patients may also develop blisters.

After blisters form, their size should be assessed. If the blister is small, it can be covered with sterile gauze to keep the area dry while awaiting natural healing. However, if the blister is large—about the size of a soybean—it should be punctured using a sterile needle. The clear yellowish fluid should then be absorbed with a sterile cotton ball. Afterward, gentian violet solution can be applied, followed by covering with gauze. Allow the area to dry and form a scab, and wait for complete healing.