• Benefits

Heart disease: Once thought of as a threat mainly to men, heart disease also is the leading killer of women in the United States. Drinking moderately may lower the risk for coronary heart disease, mainly among women over age 55. However, there are other factors that reduce the risk of heart disease, including a healthy diet, exercise, not smoking, and keeping a healthy weight. Moderate drinking provides little, if any, net health benefit for younger people. (Heavy drinking can actually damage the heart.)

• Risks

Drinking and driving: It doesn’t take much alcohol to impair a person’s ability to drive. The chances of being killed in a single-vehicle crash are increased at a blood alcohol level that a 140-lb. woman would reach after having one drink on an empty stomach.

Medication interactions: Alcohol can interact with a wide variety of medicines, both prescription and over-the-counter. Alcohol can reduce the effectiveness of some medications, and it can combine with other medications to cause or increase side effects. Alcohol can interact with medicines used to treat conditions as varied as heart and blood vessel disease, digestive problems, and diabetes. In particular, alcohol can increase the sedative effects of any medication that causes drowsiness, including cough and cold medicines and drugs for anxiety and depression. When taking any medication, read package labels and warnings carefully.

Breast cancer: Research suggests that as little as one drink per day can slightly raise the risk of breast cancer in some women, especially those who are postmenopausal or have a family history of breast cancer. It is not possible, however, to predict how alcohol will affect the risk for breast cancer in any one woman.

Source: http://pubs.niaaa.nih.gov/publications/brochurewomen/women.htm#drinking