Before you start using Humulin R, it’s important to tell your doctor about any medications, herbs, supplements, or over-the-counter drugs you are taking. Some of these can affect how Humulin R works in your body. These include antibiotics, antidepressants, certain heart medications, steroids, and cholesterol-lowering drugs, among others. Even thyroid medication and alcohol can impact how you manage your diabetes with Humulin R. So, it’s crucial to let your doctor know about everything you’re taking to ensure your treatment is safe and effective.