Key takeaways
Humulin R (insulin regular) and Humalog (insulin lispro) are both insulins used to manage blood sugar levels in people with diabetes, but they have some key differences. Humulin R is a short-acting insulin that starts working within 30 minutes and lasts for 3 to 6 hours. In contrast, Humalog is a rapid-acting insulin that begins to work within 15 minutes and lasts for 2 to 4 hours. Humulin R can be purchased over the counter, while Humalog requires a prescription. Humulin R is typically injected 30 minutes before a meal, whereas Humalog is injected within 15 minutes before or right after a meal. Both medications can cause low blood sugar and weight gain, but Humalog is also associated with flu-like symptoms and headaches. Humulin R is available in vials, while Humalog comes in various pen options and vials.
