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Can regular and lispro insulin (Humalog) be mixed?

Medically reviewed by Carmen Pope, BPharm. Last updated on June 20, 2022.

Official answer

  • Yes, they can be mixed; however, there is no real reason why you would want to mix the two as they are both short-acting insulins.
  • If you do need to mix regular and lispro insulin, draw up the lispro insulin first to prevent clouding.
  • Typically, a short-acting insulin is given with either an intermediate-acting insulin or a long-acting insulin.

It is important to always check the compatibility of insulins before you mix them.

In general, the rule: “ Clear before cloudy, draw the fastest insulin first”, should be followed.

If you need to mix regular with lispro insulin (Humalog):

  • Firstly, question the reason why? These are both short-acting insulins so clinically they are not often mixed as a short-acting insulin is usually combined with an intermediate or long-acting insulin.
  • Regular insulin is compatible with lispro, but always draw up the lispro first, and then draw up the regular insulin to prevent clouding.

Some insulins cannot be combined. For example:

  • Lantus and Levemir
  • Protamine zinc and other insulins
  • Lente insulins and NPH/isophane insulins
  • Lente insulins and protamine suspended insulins
  • Animal insulins and human or analog insulins.

Longer-acting insulins contain added buffers that make them last longer in the body, and these can settle at the bottom of a vial or precipitate out when mixed with other insulins (or mixed in the wrong order).

Do not shake a bottle of insulin. Instead, gently turn it up and down about 20 times or roll it in your hands slowly.

Lispro insulin

Lispro insulin has a rapid onset of action and peaks in one half the time and double the concentration of a comparable dose of regular insulin. It should be injected immediately before eating or with a meal.

  • Starts working within 0 to 15 minutes after administration
  • Peaks in 30 to 90 minutes
  • Keeps working for less than five hours (usually two to four hours).

Regular insulin

  • Starts to work within 30 minutes after injection
  • Peaks in 2 to 3 hours
  • Keep working for up to 8 hours.


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