Primacort 100 Injection is used to treat allergic and inflammatory conditions. It contains Hydrocortisone, which inhibits the release of certain chemical messengers in the body that cause redness, itching, and swelling. It also works as a replacement therapy for the natural steroid hormone cortisol. Common side effects of Primacort 100 Injection are acne, increased hair growth, weight gain, dizziness, nausea, muscle weakness, or indigestion.