How do you treat a rash from sun and antibiotic reaction?

To treat a rash from sun exposure and an antibiotic reaction, first, discontinue the antibiotic after consulting with a healthcare provider. Apply cool compresses to soothe the skin and use over-the-counter hydrocortisone cream to reduce inflammation. Keep the area moisturized and avoid further sun exposure. If the rash worsens or is accompanied by severe symptoms, seek medical attention promptly.