Why Shelf Life Is Important

All medications can lose potency over time. Some products are sensitive to heat, light, or physical agitation that can cause chemical or physical changes. That's why all medicines bear an expiration date. Lilly continuously studies product stability to ensure that when a patient takes a drug, it will work the way it was intended.

Shelf life is determined early in product development. But validating it is an ongoing process. Our manufacturing technicians pull representative batches from production lines for testing and observation. Raw materials from outside suppliers also go through rigorous evaluation to ensure that fresh ingredients are always used. We continue testing our products in monthly increments for up to three years. Each time we test, we record the data.

Most of Lilly's products have a two-year shelf life; a few have three years. After a product is launched, its shelf life may be prolonged if studies show that stability is maintained over a longer period of time. It's part of our commitment to government regulatory bodies to continuously test our products' stability.