The thinness of the ejaculated semen may be caused by physiological factors such as frequent masturbation or frequent sex; or pathological factors such as prostatitis and oligospermia, as follows. 1. Physiological factors: for example, frequent masturbation or too frequent sex may lead to thin semen. When the sex life is improved, the symptoms will be gradually relieved, and the consistency of the sperm will also increase significantly. 2. Prostatitis: related to long-term irregular sex life and sedentary and other factors, if not treated in time, may affect the quality of sperm, resulting in sperm thinning; in serious cases, it will affect the sexual function and fertility, and some patients will often frequent urinary frequency, urinary urgency, urinary discomfort. 3. Oligospermia: when the sperm count decreases significantly, it may cause thin semen, the sperm vitality may be poor, and there may be white blood cells in the semen. If you find that the ejaculate is thin and you are worried that it may affect your fertility, it is recommended that you seek medical attention as soon as possible and get to know the quality of the sperm by doing a semen analysis.