A normal person taking 8 glasses of water a day takes 64 ounces (1.9 liters), thus the need to constantly get rid of the excess water. The bladder stores this extra liquid and when half complete, sends signals to the brain to let one know that they ought to pee. This however, is bearable and you may decide to hold the urine for longer.
But how long is long, well it changes with various people. Others can hold it for so long while others can not hold it for long. It is however advisable that you hit the head as soon as the urge to do so comes.
While holding it for a short period has no effect apart from the difficulty to concentrate on anything else than your urge to pee, doing so for long and too many times is detrimental. It might lead to infections and other negative effects. The bacteria on the genital surface is not being flushed out, therefore it can enter through the ureter and migrate in to the bladder. If this goes untreated, the bacteria will enter the blood stream causing a systemic disorder that’s extremely life threatening.
For pregnant women, these bacteria propagate faster, there are other infections that may arise from this. They include:
Kidneys stones a condition where miniature stone like grow in the kidneys due to excessive accumulation of calcium and sodium salts along the tract. The stones make it difficult to pass urine because the pain that comes along is unbearable since the stones will be large in comparison to the tract size.
Cystitis an inflammation of the bladder walls mostly experienced by girls. Its symptoms are: pain in the pelvis, burning and pain when urinating and swelling of the bladder.
Voiding dysfunction this happens mostly in children. It’s the inability to retain urine as the sphincter muscles are weakened and are not able to relax.
The bladder may also swell because it is holding more than its capacity. Too much swelling may call for a surgery.
Other possible varied effects are anxiety, cramps, shivers and stomach aches.