The size of the flaccid penis (a penis without an erection) varies among men and there is no minimum size. Many factors, like cold, can affect the size of a flaccid penis and some men have a naturally smaller penis. A smaller penis does not affect the ability to perform sexually.
During sexual arousal, the penis will enlarge as blood fills the area and should become fully erect. Some men experience an incomplete or weak erection and this may affect sexual intercourse. Another problem is a partial erection which is quickly lost and the penis returns to a flaccid state. These problems are known as erectile dysfunction or commonly referred to as impotence, and requires medical investigation and treatment.
When aroused either due to physical or mental stimulation, the entrance to the penis cavity opens. This allows blood to rush into the cavity, filling all the space in it and causes the penis to enlarge. A membrane around the cavity keeps the blood trapped within the cavity and maintains the erection. This is how an erection occurs.
Valves at the entry point of the penis prevents blood from leaving the penis. After sexual intercourse or if stimulation decreases, the valve opens again and blood from the penis rushes out. The penis then returns to the flaccid state.
Many causes of erectile dysfunction involve the muscles that control the entrance and exit of blood into the cavity of the penis.
Weak or Incomplete Erection
In cases of a weak or incomplete erection, the problem lies in the filling and holding of blood within the penis cavity. If the muscles that control the passage of blood into the penis closes off the blood supply too early or if it cannot keep the blood within the penis, then the erection will be weak or incomplete.
Many men opt to use over-the-counter sex products, like herbal pills and penis pumps to improve the size and rigidity of an erection. Some of these products can be dangerous and may even damage structures within the penis that will allow you to get an erection naturally.
If you are experiencing any difficulty with getting an erection or if you are unable to maintain an erection, then you need to consult with a doctor. A urologist specialises in the genitourinary organs and will be best suited to investigate, treat and monitor your condition.