Prophet Muhammad (Peace be upon him) advocated that hijama should be practiced at certain times because it depends a lot on the moon. The moon has a gravitational pull on Earth resulting in a huge impact upon all life forms which includes human beings, animals, fish, plants and water bodies. It causes fluids to rise at particular times during the monthly lunar cycle. Therefore, this also includes a change in the human body.  Hence it is recommended to perform hijama at certain times. This all has to do with gravitational pull and the levels of the four fluid humors (black & yellow bile, blood and phlegm) and water inside the human body at certain times of the month. Just as the moon affects the tide of the ocean, it also affects the human body. 

According to Ibn Sina’s research, the four humors inside the human body were on the rise and in a state of agitation during the full moon. The full moon pulls the blood towards the skull during the full moon. As the moon begins to wane in the third week of the month, the fluids begin to recline in the body. The residue that is left over in the upper parts of the body is septic and should be removed through hijama, in order to cleanse the blood and cardio-vascular system.