Finasteride was initially approved in 1992 as a drug for the treatment of prostate enlargement. Later, in 1997, the U.S. Food and Drug Administration approved this drug for the treatment of male pattern hair loss. This drug is also known by its trade names propecia and proscar. Every drug may show some side effects, and this one is no exception. Some of the side effects that have been reported by patients undergoing treatment using this drug are given below. Erectile Dysfunction or Impotency Erectile dysfunction refers to the inability of a man, to keep an erection firm during the span of sexual intercourse with his partner. It is commonly known as ED, and can result in total inability to achieve erection. There are cases of inconsistency in erection or a tendency to sustain erection briefly. People on the prescription of finasteride are at times found to be prone to erectile dysfunction or impotency. It has been noticed through tests that consumption of 1 mg of this drug has caused erectile dysfunction among 1.8% of the total number of people put to test. The percent of dysfunction rises by 18.5% if the dosage is increased by 5 mg among the same number of people. Gynecomastia Gynecomastia is an abnormal development of large mammary glands in males, resulting in male breast enlargement. It is an adverse side effect of this drug, and approximately 2.2% of the people experience it during the treatment. Patients should consult their doctor if they observe a change in the size of breast. Finding an alternative medication that does not cause this condition as a side effect, is also an option that can be considered. Allergic Reactions Allergic reactions such as skin rashes, itching, difficulty in breathing and swelling of the mouth, face, lips, or tongue have also been associated with the use of this drug. Other reactions include body pain or tenderness, and nipple discharge. Testicular pain is also reported by the patients sometimes. Depression Finasteride has also been linked to depression. Some of the possible reasons for this may be the decreased sex drive or an inability to satisfy the partner. However, there may be other reasons like stress and improper dosage, which may cause depression. The severity of depression may vary from person to person, but a consistent low feeling for a particular duration may also be accounted to other factors and may be completely unrelated to the intake of the drug, however, if the degree of depression increases, the appropriate specialist must be immediately informed. Such a mental condition may be viewed as signs of clinical depression. In such cases, the doctor should immediately be consulted, and if the problem becomes severe, the medication should be stopped on the doctor's advice. Decreased Libido (Sex Drive) Some of the studies suggest that the use of this drug may result in persistent sexual side effects. It may also result in decreased or abnormal ejaculation. This drug has also known to cause birth defects in an unborn baby and should be avoided by pregnant women. It is also advisable for them, not to handle crushed or broken tablets, because the medication could be absorbed through skin. The side effects induced by finasteride are also dependent on the immune system of the patient, and not all are susceptible to the effects caused by the drug. Some people are able to tolerate the drug well, and if the side effects occur, they can easily be treated by the health care provider. It has also been reported that in controlled clinical trials, nearly 1.2% of patients on this medication have discontinued the treatment because of the drug-related adverse sexual experience.