Cups should be retained in place from 5 to 15 minutes, depending on the strength of suction. Especially in hot weather, or when cupping over shallow flesh, the duration of treatment should not be too long. Often I have seen the cups pop off for no apparent reason. If the suction was good in the first place, then generally this is an indication that suction is not needed in that place, or there was too much body hair for the cup to hold. It is also possible for the cup to remain in place and still be unnecessary, and if so, no redness or bruising will occur.
Bruises occurring under the cups indicate where the congestion has been.
I have also seen blisters appear which should be dressed and treated to prevent infection. Cupping is done over areas where there is swelling, pain or congestion, either of energy, blood or mucus. Thus, it is good for edema, swellings, asthma, bronchitis, dull aches and pains, arthritis, abdominal pain, stomach-ache, indigestion, headache, low back pain, painful menstruation, coughs from excessive mucus, and places where bodily movement is limited and painful. Cupping should not be done during high fever, convulsions or cramps, or over allergic skin conditions, ulcerated sores, or on the abdomen or lower back of pregnant women. It will also be ineffective over areas with irregular body angles, where the muscles are thin, the skin is not level or where there is a lot of body hair.