Caffeine is also an outlier as its use is seen as socially acceptable in most cultures and even encouraged in others, particularly in the Western world. Caffeine has both positive and negative health effects. It can treat and prevent the premature infant breathing disorders bronchopulmonary dysplasia of prematurity and apnea of prematurity. Caffeine citrate is on the WHO Model List of Essential Medicines. It may confer a modest protective effect against some diseases, including Parkinsons disease. Some people experience sleep disruption or anxiety if they consume caffeine, but others show little disturbance. Evidence of a risk during pregnancy is equivocal; some authorities recommend that pregnant women limit caffeine to the equivalent of two cups of coffee per day or less. Caffeine can produce a mild form of drug dependence – associated with withdrawal symptoms such as sleepiness, headache, and irritability – when an individual stops using caffeine after repeated daily intake. Tolerance to the autonomic effects of increased blood pressure and heart rate, and increased urine output, develops with chronic use (i.e., these symptoms become less pronounced or do not occur following consistent use).Caffeine is classified by the US Food and Drug Administration as generally recognized as safe. Toxic doses, over 10 grams per day for an adult, are much higher than the typical dose of under 500 milligrams per day.
Penile pain refers to pain in the penis, human or otherwise. Common causes
Penile injury
Circumcision
Penile fracture
Priapism
Phimosis
Peyronies disease
Sexually transmitted infections
Chronic prostatitis/chronic pelvic pain syndrome

Cultural references
Priapus, a minor Greek god of fertility, is marked by his oversized, permanent erection, which gave rise to the medical term priapism. Some researchers believe the depiction of Priapus penis referred to a penile disease, and that paintings of Priapus were used to ward off the disease. See also
Genital pain
Vaginal pain
Testicular pain
List of the causes of genital pain


== References ==