Brain:
Alcohol interferes with the communication pathways in the brain, and can affect the way the brain looks and works. 

Heart:
Drinking, whether a lot of a period of time or too much on a single occasion, can damage the heart and cause problems which include:

  • Cardiomyopathy - Stretching and drooping of heart muscle
    Arrhythmias - Irregular heart beat
  • Stroke
  • High Blood Pressure

Liver:
Drinking takes a toll on the liver and can lead to a multitude of problems and liver inflammations including:

  • Steatosis, or fatty liver
  • Alcoholic hepatitis
  • Fibrosis
  • Cirrhosis

Pancreas:
Toxic substances are produced due to alcohol that can eventually lead to pancreatitis, a dangerous inflammation and swelling of the blood vessels in the pancreas that prevent proper digestion

Cancer:
There is a strong scientific consensus of an association between alcohol drinking and several types of cancer. Consumption of alcoholic beverages is listed as a known human carcinogen in a repot on Carcinogens by the National Technology Program of the US Department of Health and Human Services. Research indicated that the more alcohol a person drinks, particularly the more a person drinks regularly over time, the higher the riks of developing an alcohol-associated cancer. Based on data from 2009, an estimated 3.5 percent of all cancer deaths in the United States (about 19,500) were alcohol related.

Patterns have emerged between alcohol consumption and the development of the following cancer:

  • Head and neck cancer: Consumption is a major risk factor for certain head/neck cancers; particularly cancer of the oral cavity, pharynx (throat), and larynx (voice box).
  • Esophageal cancer: Particularly esophageal squamous cell carcinoma.

    Liver Cancer: Alcohol consumption is an independent risk factor and primary cause of liver cancer.

  • Breast Cancer: More than 100 epidemiologic studies have researched the association between alcohol consupmtion and the risk of breast cancer in women, finding an increased risk with increased intake.

    Colorectal Cancer:Alcohol consumption causes a modest increased risk of cancer of the colon and rectum.

Immune System:
Drinking can weaken your immune system, making the body an easier target for disease. Chronic drinkers are more likely to contract diseases such as pneumonia and tuberculosis compared to people who do not drink. Drinking heavily on a single occasion also slows the body's ability to ward off infection - this can last up to 24-hours after getting drunk.

Sources:
https://www.niaaa.nih.gov/alcohols-effects-health/alcohols-effects-body
https://www.cancer.gov/about-cancer/causes-prevention/risk/alcohol/alcohol-fact-sheet