If you have diabetes, your doctor may prescribe Humalog.

It’s used to help manage blood sugar levels in adults and some children. And it can be given to people with either type 1 or type 2 diabetes.

Humalog basics

Humalog comes in two forms: Humalog and Humalog Mix.

Humalog is a solution that can be given:

Humalog Mix is a liquid suspension (a type of liquid mixture) that you’ll take as an injection under your skin.

Humalog and Humalog Mix aren’t regular insulins.* Instead, they’re rapid-acting insulins. This type of insulin starts to work 15 minutes after it’s injected. And the insulin’s effect in your body lasts between 2 and 4 hours. Humalog Mix also contains a longer-acting insulin that lasts up to 22 hours.

Humalog and Humalog Mix are biologic medications that contain insulin lispro. Humalog Mix also contains insulin lispro protamine. The manufacturer of these drugs also makes insulin lispro and insulin lispro protamine available as biosimilars. (A biologic drug is made from parts of living cells. Biosimilars are like generic drugs. But unlike generics, which are made for nonbiologic drugs, biosimilars are made for biologic drugs.)

In this article we describe how to take Humalog and Humalog Mix, their side effects, and more.

* Regular insulin is short-acting. It works 30 to 60 minutes after it’s given.

Your doctor will explain how you should take Humalog. They’ll also explain how much to take and how often. Be sure to follow your doctor’s instructions. Below are commonly used dosages, but always take the dosage your doctor prescribes.

Taking Humalog

Humalog comes in two forms: Humalog and Humalog Mix.

Humalog

Humalog comes as a solution. Your doctor may prescribe Humalog as:

  • An injection under your skin, using one of the following forms:
    • the Humalog KwikPen
    • the Humalog Tempo Pen
    • a cartridge and reusable insulin pens
  • A type of injection under your skin that’s given by an insulin pump. (An insulin pump will inject Humalog under your skin over a period of time.)
  • An intravenous (IV) infusion, which is an injection into a vein that’s given over time, by your doctor or another healthcare professional.

Humalog contains either 100 units or 200 units of insulin lispro in each milliliter of solution. Your prescription for Humalog may state either “U-100” or “U-200” depending on which strength of the drug your doctor prescribes.

But only Humalog KwikPens come as either U-100 or U-200. Other Humalog pens, vials, and cartridges come only as U-100. (Cartridges hold insulin and are used in reusable insulin pens.)

Humalog Mix

Humalog Mix is a suspension (a type of liquid mixture) that you’ll take as an injection under your skin. You can use the Humalog Mix KwikPen to inject the drug under your skin. Or, you can use the Humalog Mix vial with insulin syringes.

Humalog Mix comes in U-100 strength. It’s available as:

  • Humalog Mix 50/50, which contains 50% insulin lispro and 50% insulin lispro protamine
  • Humalog Mix 75/25, which contains 75% insulin lispro protamine and 25% insulin lispro

Dosage

The best time to administer Humalog is either 15 minutes before you eat or right away after you’ve eaten. Your doctor will tell you how much to take for your doses.

How much Humalog you’ll take varies depending on:

If you’re in a hospital and you need insulin, your doctor may use a dosage scale for Humalog. A dosage scale involves taking small doses of Humalog or another rapid-acting insulin as needed depending on your current blood sugar level. Your healthcare professionals will manage your insulin injections if you’re staying in a hospital.

Humalog sliding scale

In the past, doctors would prescribe Humalog on a sliding scale to quickly lower a person’s blood sugar level depending on their blood sugar readings. With a sliding scale, small amounts of Humalog are injected as needed based on your current blood sugar level.

Using a sliding scale requires you to test your blood sugar at home and calculate your insulin dose based on the scale. But this dosage scale is no longer recommended.

According to experts, Humalog sliding scales don’t control blood sugar levels because they’re a reactive treatment. Sliding scales react to your current blood sugar level. But sliding scales don’t manage your insulin needs based on your past blood sugar readings.

Taking Humalog with other drugs

You may need to take other medications together with Humalog to manage your blood sugar levels.

If you’re taking insulin such as Humalog, your doctor may decrease the dosage of, or have you stop taking, other diabetes drugs that increase your insulin level. Doing so helps prevent your blood sugar levels from dropping too low.

Examples of other diabetes medications that may be used with Humalog include:

  • metformin (Glucophage)
  • glyburide (Diabeta)
  • repaglinide
  • acarbose
  • pioglitazone (Actos)
  • liraglutide (Victoza)
  • sitagliptin (Januvia)
  • saxagliptin (Onglyza)
  • canagliflozin (Invokana)
  • insulin products other than Humalog

If you’d like to know more about taking other drugs with Humalog, talk with your doctor.

Questions about taking Humalog

Below, we answer common questions related to taking Humalog.

  • What if I miss a dose of Humalog? If you miss a dose of Humalog, take the missed dose as soon as you remember. But if it’s been longer than 1 hour since you’ve eaten, just skip the missed dose. Then, take your next dose with your following meal like usual. Your body will start to lower your blood sugar naturally after you eat. So, injecting Humalog more than 1 hour after eating may cause your blood sugar to drop to unsafe levels. If you receive Humalog infusions from a healthcare professional, reschedule any missed appointments as soon as possible.
  • Will I need to use Humalog long term? Diabetes, which Humalog is used to manage, is a long-term condition. So you may need to take Humalog long term if your doctor recommends it. Talk with your doctor about how long you’ll need to take this drug.
  • Should I take Humalog with food? You’ll take Humalog either 15 minutes before eating or right away after eating. If you don’t eat, taking Humalog may lower your blood sugar levels to dangerously low levels.
  • How long does it take for Humalog to work? Humalog and Humalog Mix work quickly to lower your blood sugar. Within 15 minutes after injection, the drugs start to lower your blood sugar levels. And after 1 hour, Humalog will have its maximum effect in your body. Humalog’s effect can last up to 4 hours. And because Humalog Mix contains a mixture of insulins, its effects can last up to 22 hours.
Questions for your doctor

You may have questions about Humalog and your treatment plan. It’s important to discuss all your concerns with your doctor.

Here are a few tips that might help guide your discussion:

  • Before your appointment, write down questions like:
    • How will Humalog affect my body, mood, or lifestyle?
  • Bring someone with you to your appointment if doing so will help you feel more comfortable.
  • If you don’t understand something related to your condition or treatment, ask your doctor to explain it to you.

Remember, your doctor and other healthcare professionals are available to help you. And they want you to get the best care possible. So don’t be afraid to ask questions or offer feedback on your treatment.

Humalog and Novolog are both used to manage blood sugar levels in people with diabetes. Novolog contains insulin aspart, while Humalog contains insulin lispro.

Both Humalog and Novolog are rapid-acting insulins, which means they work quickly after they’re injected. But these drugs can’t be substituted for one another.

Novolog can be used in adults and children ages 2 years and older. But Humalog can only be used in adults and children ages 3 years and older.

For a detailed comparison of these two drugs, see our “Humalog vs. Novolog: Important Differences and More” article. And talk with your doctor if you have more questions about these medications.

Humalog and Humulin aren’t the same drug. Humulin contains human insulin, while Humalog contains insulin lispro. And different Humulin products also contain different types of insulin.

For example:

  • Humulin-R contains rapid-acting human insulin that’s injected 30 minutes before eating.
  • Humulin-N, on the other hand, contains a type of human insulin called isophane insulin. It’s an intermediate-acting insulin that takes longer to start working and lasts longer in your body.

Humalog also comes as Humalog Mix, which contains a mixture of rapid-acting and intermediate-acting forms of insulin lispro. Similarly, another product called Humulin 70/30 contains a mixture of rapid and intermediate-acting human insulin.

If you’d like to know more about the differences and similarities of Humalog and Humulin, see this drug article. And be sure to talk with your doctor about which drug is right for you.

Humalog is a biologic medication containing the active ingredient insulin lispro. A biologic medication is made from parts of living organisms.

The manufacturer of Humalog also makes a biosimilar form of the drug called insulin lispro. (Biosimilars are like generic drugs. But unlike generics, which are made for nonbiologic drugs, biosimilars are made for biologic drugs.)

In some cases, the brand-name drug and the biosimilar version may come in different forms and strengths.

Talk with your doctor if you’d like to know more about insulin lispro.

Like most drugs, Humalog may cause mild or serious side effects. The lists below describe some of the more common side effects that Humalog may cause. These lists don’t include all possible side effects.

Keep in mind that side effects of a drug can depend on:

  • your age
  • other health conditions you have
  • other medications you may be taking

Your doctor or pharmacist can tell you more about the potential side effects of Humalog. They can also suggest ways to help reduce side effects.

Mild side effects

Here’s a short list of some of the mild side effects that Humalog can cause. To learn about other mild side effects, talk with your doctor or pharmacist, or read the patient information for the forms of Humalog* below:

Mild side effects of Humalog that have been reported, and are discussed below in “Side effect focus” include:

Mild side effects of many drugs may go away within a few days or a couple of weeks. But if they become bothersome, talk with your doctor or pharmacist.

* Humalog comes in different forms and strengths. For more information, see the “How is Humalog taken?” section above.

Serious side effects

Serious side effects from Humalog can occur, but they aren’t common. If you have serious side effects from Humalog, call your doctor right away. But if you think you’re having a medical emergency, you should call 911 or your local emergency number.

Serious side effects of Humalog that have been reported include:

* For more information on this side effect, see the “Side effect focus” section below.

Side effect focus

Learn more about some of the side effects Humalog may cause.

Weight gain

You can gain weight while you’re taking Humalog, or any other insulin product.

Experts say that this happens because with treatment of high blood sugar levels, you’re no longer urinating as often or as much as before. And insulins are used to manage high blood sugar levels.

Also, insulin helps your body’s cells absorb sugar from your bloodstream. But when your cells absorb too much sugar, your body makes fat. And this may lead to weight gain.

What might help

Your dose of insulin may need to be adjusted if you gain or lose weight during treatment. Talk with your doctor if you’re concerned about your weight and your dosage of Humalog.

If you’re gaining weight with Humalog, ask your doctor about ways to manage your nutrition and level of physical activity. Your doctor can help you develop a plan to manage your weight. Additionally, a nutritionist may be able to help you plan meals that are beneficial for people with diabetes. And an exercise specialist can suggest ways to add physical activity into your lifestyle.

Low blood sugar level

If you have a low blood sugar level, which is also called hypoglycemia, you shouldn’t take Humalog. This is because the drug will lower your blood sugar even more.

Usually, hypoglycemia occurs when your blood sugar level is below 70 milligrams/deciliter (mg/dL). The normal range for fasting blood sugar level in people with diabetes is 80 mg/dL to 130 mg/dL.

Symptoms of low blood sugar can include:

  • anxiety or nervousness
  • sweating or having chills
  • irritability, impatience, or confusion
  • fast heart rate
  • dizziness
  • skin that looks paler than usual
  • blurred or impaired vision
  • headache

What might help

When injecting insulin, including Humalog, you should be aware of the symptoms of low blood sugar levels. And be sure to check your blood sugar levels per your doctor’s instructions.

Additionally, to help prevent low blood sugar, follow your doctor’s instructions for taking Humalog.

If you do have low blood sugar with Humalog, make sure to consume something with sugar that can be quickly absorbed by your body. Such items include:

  • sugar tablets or gel
  • 4 ounces of juice or regular soda (not sugar-free or diet versions)
  • 1 tablespoon of sugar, honey, or corn syrup
  • hard candies, jellybeans, or gumdrops

To raise your blood sugar level, you’ll need to ingest 15 grams (g) of sugar. If your blood sugar still hasn’t increased after 15 minutes, you should ingest another 15 g of sugar.

Lipodystrophy

It’s possible to have lipodystrophy while you’re using Humalog. This condition causes changes in the way fat tissue is distributed in your body. It can occur when you inject insulin, such as Humalog, into the same area.

With lipodystrophy, you may have pitting or thickened areas on your skin.

What might help

You’ll inject Humalog under the skin of your stomach, thigh, arm, or buttocks. To help prevent lipodystrophy, you’ll need to change your injection site each time you inject the drug. This means you’ll avoid injecting into the exact same spot for each injection.

You should also avoid injecting into areas of your body that already have altered fat distribution. These areas may look pitted, thickened, or lumpy. Also, don’t inject Humalog where your skin is tender, scarred, or damaged.

Allergic reaction

Some people may have an allergic reaction to Humalog.

Symptoms of a mild allergic reaction can include:

  • skin rash
  • itchiness
  • flushing (warmth, swelling, or redness, or discoloration in your skin)

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include swelling under your skin, typically in your eyelids, lips, hands, or feet. They can also include swelling of your tongue, mouth, or throat, which can cause trouble breathing.

Call your doctor right away if you have an allergic reaction to Humalog. But if you think you’re having a medical emergency, call 911 or your local emergency number.

Find answers to some commonly asked questions about Humalog.

What’s the difference between Humalog and Admelog?

Like Humalog, Admelog is a rapid-acting insulin that’s used to manage blood sugar levels in people with diabetes. (Rapid-acting insulin works 15 minutes after it’s injected.)

Like Humalog, Admelog is taken by injection under your skin or injection into your vein. Additionally, both of these medications can be taken as an injection through an insulin pump. (Insulin pumps continuously deliver insulin into your body.)

Admelog is used in adults and some children with type 1 or type 2 diabetes, just like Humalog is. And Admelog contains the same active ingredient as Humalog: insulin lispro. But Humalog and Admelog can’t be substituted for each other.

Admelog is a follow-on version of Humalog. This means that it was developed by a different drug company as their version of Humalog.

If you have more questions about these two drugs, talk with your doctor. They can recommend which medication would be the best treatment option for you.

How fast does Humalog work?

Humalog comes in two forms: Humalog and Humalog Mix.

The onset of Humalog’s action is 15 minutes after it’s injected. This means that the action time starts 15 minutes after you take a Humalog injection. And the drug’s action time lasts about 2 to 4 hours, with a peak effect after 1 hour. (Peak effect is when the drug has its maximum effect in your body.)

Humalog is a rapid-acting insulin, but it loses its effect quickly. This is unlike long-acting insulin, which takes longer to start working, but is longer lasting.

Humalog Mix contains a mixture of rapid-acting insulin and longer-acting insulin. Like Humalog, Humalog Mix starts working 15 minutes after it’s injected. But its effects can last up to 22 hours.

How long does Humalog last in your body?

Humalog comes in two forms: Humalog and Humalog Mix. Each form can last a different amount of time in your body.

Humalog can last about 4 to 5 hours in your body, while Humalog Mix can last about 22 hours.

Humalog’s half-life is 1 hour. This means that half of a dose of Humalog will be eliminated by your body after 1 hour. In general, after about four to five half-lives, a medication reaches very low levels and is eliminated from your body.

The half-life of Humalog Mix isn’t known for sure.

Does Humalog need to be refrigerated?

Yes, unopened Humalog and Humalog Mix need to be refrigerated until you’re ready to use them. After getting Humalog or Humalog Mix from your pharmacy, you should place the unopened drug into your refrigerator. And make sure the temperature is between 36°F and 46°F (2°C and 8°C).

Once you open Humalog or Humalog Mix, you can store it at room temperature, but below 86°F (30°C). You’ll have to use Humalog vials, cartridges, and prefilled pens within 28 days. And you’ll have to use Humalog Mix vials within 28 days, or the prefilled pens within 10 days.

Any unused Humalog Mix vials or Humalog vials, cartridges, and prefilled pens should be discarded after 28 days if kept at room temperature. Any unused Humalog Mix prefilled pens should be discarded after 10 days if kept at room temperature.

Some important things to discuss with your doctor when considering Humalog include:

  • your overall health
  • any medical conditions you may have

Also, tell your doctor if you’re taking any medications. This is important to do because some drugs can interfere with Humalog.

These and other considerations are described below.

Interactions

Taking medications, vaccines, foods, and other things with a certain drug can affect how the drug works. These effects are called interactions.

Before taking Humalog, be sure to tell your doctor about all medications you take (including prescription and over-the-counter types). Also describe any vitamins, herbs, or supplements you use. Your doctor or pharmacist can tell you about any interactions these items may cause with Humalog.

Interactions with drugs or supplements

Humalog can interact with several types of drugs, such as:

This list does not contain all types of drugs that may interact with Humalog. Your doctor or pharmacist can tell you more about these interactions and any others that may occur with use of Humalog.

Warnings

Humalog may not be suitable for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you take Humalog. Factors to consider include those in the list below.

  • Hypoglycemia. Low blood sugar (hypoglycemia) can be life threatening. Your doctor may suggest increasing how often you check your blood sugar levels when you first start Humalog or whenever your dosage is changed. During these times, you have a higher risk for hypoglycemia with Humalog.
  • Allergic reaction. If you’ve had an allergic reaction to Humalog or any of its ingredients, you shouldn’t take Humalog. Ask your doctor what other medications are better options for you.
  • Low blood potassium levels. If you have low potassium levels in your blood, taking Humalog may be dangerous. If you develop low potassium levels during treatment with Humalog, your doctor may tell you to stop taking the drug. Your doctor may also have you take supplements to raise your potassium levels.

Use with alcohol

Alcohol can affect Humalog’s effect in lowering your blood sugar level.

Specifically, alcohol can cause insulin, such as Humalog, to act stronger than usual. And this can increase your risk for low blood sugar and other side effects.

Be sure to tell your doctor if you drink alcohol. Let them know how much and how often you drink. Your doctor may adjust your Humalog dosage if needed. Don’t drink alcohol or take medications that contain alcohol while using Humalog before first talking with your doctor.

Pregnancy and breastfeeding

Doctors don’t have enough information on whether Humalog is harmful if used by pregnant people.

Studies show that Humalog doesn’t increase the risk of major problems with fetal development (commonly known as birth defects), pregnancy loss, or other problems during pregnancy. And there’s more risk for a pregnant person and their fetus if diabetes isn’t well-managed during pregnancy.

Currently, doctors aren’t sure whether Humalog:

  • passes into human breast milk, or
  • has an effect on a child who is breastfed or your body’s milk production

If you’re pregnant or breastfeeding, talk with your doctor about the benefits and risks of taking Humalog.

Costs of prescription drugs can vary depending on many factors. These factors include what your insurance plan covers and which pharmacy you use.

The active ingredient in Humalog, insulin lispro, is available in biosimilar form. And the manufacturer has also made the active ingredients in Humalog Mix available in biosimilar form. These are called insulin lispro and insulin lispro protamine.

Similar to generics, biosimilars often cost less than brand-name drugs. (Biosimilars are like generic drugs. But unlike generics, which are made for nonbiologic drugs, biosimilars are made for biologic drugs such as Humalog.)

If you have questions about how to pay for your prescription, talk with your doctor or pharmacist. You can also visit the Humalog manufacturer’s website to see if it has support options.

If you have diabetes, your doctor may prescribe Humalog.

The drug works to help manage blood sugar levels in people with either type 1 or type 2 diabetes.

Humalog comes in two forms: Humalog and Humalog Mix. Below are the specific uses for each:

  • Humalog is used in adults with type 1 or type 2 diabetes. Humalog is also used in children ages 3 years and older with type 1 diabetes. It’s not known if Humalog is safe or effective for children with type 2 diabetes.
  • Humalog Mix is used in adults with type 1 or type 2 diabetes. It’s not known if Humalog Mix is safe or effective for children.

With diabetes, your body either doesn’t make enough insulin, or it doesn’t respond to insulin normally. Insulin is a hormone that helps lower your blood sugar level. It brings sugar out of your blood and into your cells, where the sugar is used for energy. So, with diabetes, your blood sugar level is higher than normal.

Humalog and Humalog Mix contain a type of insulin called insulin lispro. Humalog Mix also contains a type of insulin called insulin lispro protamine. The drugs lower your blood sugar levels by:

  • helping your muscle and fat cells take in sugar from your blood
  • blocking your liver from making sugar
  • stopping your body’s breakdown of fat and protein so that your body will use up sugar instead

Don’t take more Humalog than your doctor prescribes. Using more than this can lead to serious side effects.

If you take too much Humalog, your blood sugar may drop too low, causing hypoglycemia (low blood sugar level). A severe overdose of Humalog can cause your blood sugar to drop very low, which can be life threatening.

Symptoms of severe hypoglycemia

Overdose of Humalog can cause severe hypoglycemia, which may lead to these symptoms:

What to do in case you take too much Humalog

If you have a glucagon injection available, ask someone to inject it for you, if you’re unable to do so yourself. (Glucagon will quickly raise your blood sugar level.)

Also, call your doctor if you think you’ve taken too much Humalog. You can also call 800-222-1222 to reach the American Association of Poison Control Centers, or use its online resource. But if you have severe symptoms, immediately call 911 (or your local emergency number) or go to the nearest emergency room.

Note:If you haven’t already, be sure to talk with your doctor about when and how to use glucagon.

If you have questions about taking Humalog, talk with your doctor or pharmacist. Your doctor can tell you about other treatments you can use for your condition. Here’s a list of articles that you might find helpful.

Some questions to ask your doctor about Humalog may include:

  • How can I store Humalog if I am traveling to a warmer climate?
  • How often do I need to check my blood sugar level while I’m taking Humalog?
  • What should I do if I notice pits, thickened areas, or lumps of fat develop around my belly?
  • How often do I need to change out Humalog needles?

You can learn more about the uses of Humalog by subscribing to Healthline’s type 2 diabetes newsletter. You can also read advice and stories from others with your condition in the Bezzy T2D community.

Q:

What is the difference between Humalog KwikPen and Humalog Tempo Pen?

Anonymous

A:

Humalog KwikPens and Humalog Tempo Pens are very similar.

These pens work in the same way. But Tempo Pens can connect with a smartphone app to record your insulin doses. Humalog KwikPens don’t have this feature.

Both KwikPens and Tempo Pens hold 3 milliliters (mL) of insulin. But Tempo pens come in a strength of 100 units of insulin per mL (U-100), while KwikPens come both as U-100 and U-200, which hold 200 units of insulin per mL.

If you’d like to know more about the differences and similarities of these pens, talk with your doctor. They can recommend which device would be a better option for your needs.

The Healthline Pharmacist TeamAnswers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.