What to Know About the Humalog Cartridge

There are many types of insulin available. This allows the many people with Type 1 and Type 2 diabetes flexibility in finding what works best for them. Insulin also comes with a few options of how to give your doses. Vials, insulin pens, and insulin cartridges are among the most well known.

One commonly prescribed brand of rapid-acting insulin is Humalog (insulin lispro). It comes in multiple dosage forms, including Humalog KwikPens, Humalog cartridges, and concentrated Humalog.

Keep reading to learn more about your dosage options with Humalog.

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What is rapid-acting insulin?

Rapid-acting insulin lowers blood sugar levels quickly. Once injected, it can take effect within 15 minutes and can last anywhere from 2 to 4 hours.

Humalog is one brand of rapid-acting insulin. As mentioned, it comes in vial, insulin pen, and cartridge form. Humalog has two different doses: U-100 and U-200. U-100 means there are 100 units of insulin in every 1 mL. U-200 means there are 200 units of insulin in every 1 mL. Humalog U-200 is only available as an insulin pen.

Other examples of rapid-acting insulin include:

• NovoLog (insulin aspart): The dose is 100 units/mL, and it is available in vials, FlexPens, and cartridges.

• Apidra (insulin glulisine): The dose is also 100 units/mL, and it is available in vials, SoloStar pens, and cartridges.

When is a Humalog cartridge used?

A Humalog cartridge is most often used with an insulin pump. Insulin pumps are helpful for people who need to inject insulin several times a day. They’re more commonly used by people with Type 1 diabetes. 

Using a Humalog cartridge can help lower the number of times you have to inject yourself. But using an insulin pump is a personal choice, based on what suits your lifestyle and insulin needs.

The Humalog cartridge can also be utilized in a reusable insulin pen. The Humalog KwikPen is a disposable insulin pen, meaning you throw the device away once you’ve used all the insulin inside. Reusable insulin pens are designed to be kept and refilled with cartridges, such as the Humalog one, meaning you only dispose of the cartridge.

The Humalog cartridge can also be used with reusable smart insulin pens. These devices look similar to reusable insulin pens. But they also include technology to help you better manage your insulin doses. Typically, smart insulin pens are paired with a smartphone app to help you track your insulin use. Some also work alongside continuous glucose monitors (CGMs) to help you track both your insulin use and blood sugar readings in one place.

Is the Humalog U-200 KwikPen similar to other rapid-acting insulins?

The Humalog U-200 KwikPen has the same active ingredient, insulin lispro, as the Humalog cartridge, U-100 vial, and U-100 KwikPen. But Humalog U-200 provides a higher dose of insulin in every 1 mL.

NovoLog and Apidra have different active ingredients than Humalog. So although they’re also rapid-acting insulins, they may provide a different effect. You should never switch between brands of insulin without your healthcare provider’s OK. However, switching from a brand-name insulin to a biosimilar (generic) insulin shouldn’t cause problems.

How is the Humalog U-200 used?

Using the Humalog U-200 KwikPen is similar to using the Humalog U-100 KwikPen. Here are 15 steps for using both:

1. Gather your supplies. You’ll need your insulin pen, an unused pen needle, two alcohol swabs, and gauze or a cotton ball.

2. Wash your hands with soap and water.

3. Remove the cap from your KwikPen. Wipe the rubber end with an alcohol swab.

4. Pick up your unused pen needle. Remove the paper covering. Do not remove the plastic covering yet.

5. Push the pen needle onto the pen and twist the needle to tightly secure it.

6. Carefully remove both the outer plastic covering and the inner needle shield.

7. Prime your KwikPen by dialing up 2 units of insulin using the knob on the back of your pen.

8. Hold your KwikPen with the needle pointing toward the ceiling. Make sure any air bubbles in the cartridge window rise to the top. Gently tap the window to help all air bubbles rise.

9. Keeping the needle pointing upward, press the dose knob button until the number of units reads “0” again.

10. Wipe the skin of your injection area with an alcohol swab. Let it air dry.

11. Dial up the number of units your healthcare provider has instructed you to use on your KwikPen. Even numbers of units are printed on the dose dial. Odd numbers are marked with a single horizontal line.

12. Insert the needle into your skin. Push the dose knob all the way in. Hold the knob in and slowly count to five before removing the needle. Check to make sure the dial reads “0” again. This means your whole dose was injected.

13. Use gauze or a cotton ball for bleeding if needed. Any bleeding after a dose should be minimal and stop quickly.

14. Carefully remove the pen needle from the pen. Dispose of the needle in a sharps container. Place the KwikPen’s cap back on the pen.

15. Be sure to use a different injection location with your next dose to prevent skin irritation and lipohypertrophy.

What are common side effects of Humalog?

Humalog side effects can vary slightly, depending on whether you have Type 1 or Type 2 diabetes. However, the most common side effect of this medication is low blood sugar (hypoglycemia). 

This side effect can be dangerous, which is why you’ll likely be instructed to test your blood sugar a few times a day while using Humalog.

Other common side effects include:

• Flu (more common for people with Type 1 diabetes)

• Headaches

• Pain

• Cough (more common for people with Type 1 diabetes)

• A higher risk for infections

Weight gain is possible with all insulins, including Humalog. On average, people gain less than 5 pounds after starting insulin. Discuss the best ways to manage this side effect with your healthcare provider.

Lipohypertrophy can happen with insulin injections. This is when you form thick skin where you inject medications. It can happen when you use the same injection site too often. Lipohypertrophy can make it hard to inject a needle into your skin. Changing injection areas can help lower the risk of this side effect.

Is there an advantage to using Humalog U-200 compared to Humalog U-100?

Yes. Concentrated insulin, like Humalog U-200, can be helpful for people who need to inject large doses (100 units of Humalog or more) at one time. In these cases, a person can inject a smaller volume of insulin. This can be more comfortable for some people.

There’s also concern that large volumes of insulin may not be fully absorbed. And if insulin isn’t fully absorbed, it may not be as effective as it should be. Humalog U-200 helps to prevent this absorption issue.

Lastly, concentrated insulin pens can help save people money. Humalog U-200 and U-100 KwikPens both contain 3 mL of insulin in each pen. This means the concentrated pens have double the number of units as the traditional pens. This could mean less trips to the pharmacy and less pens filled per prescription. 

If you’re looking to lower the number of times you need a Humalog refill, discuss Humalog U-200 with your healthcare provider.

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Written by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

Edited by:

Samvida Patel, MNSP, INHC

Samvida Patel, MNSP, INHC, is a health editor at GoodRx. She is a nutritionist and integrative nutrition health coach with over 8 years of experience in health communications.

Reviewed by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

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