Epigenetics investigates heritable, reversible gene regulatory mechanisms beyond DNA sequence, including phosphorylation, acetylation, ubiquitination, and methylation of DNA and histones. Recent research highlights epigenetics' role in illnesses like cancer, and neurological, metabolic, and cardiovascular conditions. Reversible epigenetic changes offer therapeutic potential, with existing use of epigenetic drugs in certain neurological disorders and tumors. This survey discusses major diseases with epigenetic involvement and emerging medications for treatment.