Aromasin 25 mg is a medication used to treat breast cancer. It is a hormonal therapy that belongs to a group of drugs called aromatase inhibitors. Aromasin 25 mg comes in the form of a tablet and is taken once daily, usually after a meal. This medication works by blocking the production of the hormone estrogen, which can cause breast cancer cells to grow. Aromasin 25 mg can also help reduce the risk of the cancer coming back and developing in other parts of the body. The tablets must be taken for as long as your doctor prescribes. Possible side effects of taking Aromasin 25 mg include hot flashes, headache, weight gain, decreased interest in sex, fatigue, joint pain, hair loss, and depression.