Hello, It commonly happens due to aging, excessive weight gain, too much smoking, side effects of certain medications taken, excessive self-pleasuring, etc. You are suggested to be careful while taking medications that cause side effects and are affecting the penis. Avoid prolonged self-pleasuring, avoid use of sex toys for a couple of days. Maintain healthy weight. Do regular walking and exercises to reduce the fat accumulation in the penis. Check out for underlying medical condition that may be causing shrinkage of the penis. Get treated any prostrate problem or Peyronie’s disease. When not treated, Peyronie’s disease, it will reduce the length and circumference of a penis. Anti-hypertensive medicines are used too. To increase the blood flow, hemorheologic agents are given. Penile traction, etc. is helpful. Get clinically examined by a urologist, you will be treated by surgery if needed. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Nupur K., General & Family Physician