Lyumjev (insulin lispro-aabc) can cause side effects ranging from mild to serious. More common side effects include rash and itching. If Lyumjev’s side effects become bothersome, talk with your doctor about treatment tips and options.

Lyumjev is used in adults and children ages 1 year and older with type 1 diabetes or type 2 diabetes to help manage blood sugar.

Keep reading to learn about the common, mild, and serious side effects Lyumjev can cause. Lyumjev is available in the following forms:

  • KwikPen
  • Junior KwikPen
  • Tempo Pen
  • cartridge for single-patient use
  • vial for multiple doses

The side effects explained in this article pertain to all available forms of Lyumjev unless noted otherwise. To learn more about Lyumjev, including its uses, dosage, and cost, read this Lyumjev overview article.

Lyumjev can cause certain side effects, some more common than others. These side effects may be temporary, lasting a few days to weeks. Talk with your doctor if side effects do not go away, get worse, or become difficult to tolerate.

Lyumjev’s commonly reported side effects include:

For more information about some of these side effects, see the “Side effect specifics” section.

The following sections include more side effects of Lyumjev. Each person’s experience with side effects may differ.

Mild side effects have been reported with Lyumjev. These include:

In most cases, these side effects should be temporary. Some are managed easily. But if you have symptoms that are ongoing or bothersome, talk with your doctor or pharmacist. Do not stop using Lyumjev unless your doctor recommends it.

Lyumjev may cause mild side effects other than those listed above. See the drug’s prescribing information for details.

For more information about some of these side effects, see the “Side effect specifics” section.

Lyumjev may cause serious side effects. The following list may not include all possible serious side effects of the drug. For more information, you can refer to Lyumjev’s prescribing information.

If you develop serious side effects while using Lyumjev, call your doctor right away. If the side effects seem life threatening or you think you’re having a medical emergency, immediately call 911. Or call your local emergency number.

Serious side effects that have been reported include:

Note: Symptoms of heart failure are especially a concern in people also taking thiazolidinedione (TZD). One example of a TZD drug is pioglitazone (Actos).

For more information about some of these side effects and their symptoms, see the “Side effect specifics” section.

Allergic reaction

For some people, Lyumjev can cause an allergic reaction. In general, symptoms of an allergic reaction can be mild or serious. But some people have had a serious allergic reaction with Lyumjev, including these symptoms:

  • difficulty breathing
  • rash over the entire body
  • fast heartbeat
  • sweating
  • feeling faint
  • swelling of the face, tongue, or throat

Your doctor or child’s doctor should monitor the allergic reaction with Lyumjev. In some situations, they may recommend stopping treatment with Lyumjev.

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest a treatment to manage your symptoms. They also can determine whether you should keep using Lyumjev.

If you have symptoms of a severe allergic reaction, such as swelling or difficulty breathing, call 911. Or call your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

Your doctor can confirm whether you’ve had a serious allergic reaction to Lyumjev. If so, they may have you switch to a different treatment.

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

Low blood sugar (hypoglycemia)

Low blood sugar was a common serious side effect reported in studies of Lyumjev. Low blood sugar may cause symptoms such as:

  • sweating
  • dizziness or lightheadedness
  • headache
  • confusion
  • slurred speech
  • blurred vision
  • fast heartbeat
  • shakiness
  • hunger
  • irritability, anxiety, or mood changes

Factors that can increase the risk of low blood sugar when using this drug include:

  • changes in your meal patterns
  • changes in your physical activity level
  • taking certain other medications

What you can do

It’s best to be prepared for a low blood sugar episode ahead of time. That way, you or someone on your behalf can take the appropriate action. You should also be prepared to monitor your sugar level during Lyumjev treatment. Your doctor may suggest monitoring your level more frequently, especially if you’re at risk of low blood sugar.

Discuss the best course of action with your doctor ahead of time. Some of their recommendations may include the following, but they’ll provide more specific recommendations and guidelines for you.

  • Use glucagon (available as an injection or nasal powder), for which you’ll need a prescription.
  • Follow the 15-15 rule, which involves eating 15 grams of carbs and then waiting 15 minutes to check blood sugar.
  • Eat certain foods, such as juice, regular soda, or glucose tablets.

Once you get recommendations from your doctor, be sure to share them with someone you trust. This will help them be prepared to act appropriately if you experience low blood sugar and aren’t able to treat it yourself.

Note: The manufacturer of Lyumjev notes that Lyumjev and other insulins should not be used during episodes of low blood sugar.

Low potassium in the blood (hypokalemia)

Low potassium in the blood was a common serious side effect reported in studies of Lyumjev. Low potassium in the blood may cause symptoms such as:

Factors that can increase the risk of low potassium in the blood when using this drug include:

  • taking other medications known to cause low potassium
  • inadequate nutrition
  • potential endocrine system disorders

What you can do

If you have low potassium in the blood during Lyumjev treatment, talk with your doctor. They’ll likely recommend that you take potassium orally or receive it by intravenous (IV) injection (into a vein).

Sudden onset of high blood sugar and high amounts of ketones in the blood or urine

Sudden onset of high blood sugar and high amounts of ketones in the blood or urine (ketoacidosis) was an uncommon serious side effect reported in studies of Lyumjev. This side effect was due to insulin pump problems and may cause symptoms such as:

Factors that can increase the risk of ketoacidosis when using this drug include:

What you can do

If you have ketoacidosis during Lyumjev treatment, you should alert your doctor right away. This condition cannot be treated with over-the-counter medications. Instead, your doctor may recommend that you receive the following:

  • intravenous (IV) insulin (IV means an injection into a vein)
  • electrolyte replacement
  • IV fluids
  • supportive care

Here are some frequently asked questions about the drug’s side effects and their answers.

How do side effects of Lyumjev in children compare with side effects reported in adults?

Various studies examined the use of Lyumjev in adults and children. Two studies examined the use of Lyumjev with basal insulin in people who have type 1 diabetes. One study involved adults and the other involved children with an average age of 12 years.

Both studies reported sore throat and irritated nasal passages (nasopharyngitis). The study involving children also reported upper respiratory tract infection.

Other side effects are possible, as each person’s experience with Lyumjev may differ.

What are Lyumjev’s side effects vs. Humalog’s and Fiasp’s?

Lyumjev, Humalog, and Fiasp all are approved to improve blood sugar management in adults and certain children with type 1 diabetes or type 2 diabetes. Each drug was studied using different markers. These include length of time, age of adults, additional insulins used, and other measures.

Because of these different markers, this table lists some side effects noted in adults using each drug in the studies. But it’s not intended to compare drugs or studies.

DrugSide effects in adults with type 1 diabetesSide effects in adults with type 2 diabetes
LyumjevLyumjev at mealtime, with basal insulin:
• sore throat and irritated nasal passages (nasopharyngitis)

Continuous infusion of Lyumjev:
• infusion site reaction
• infusion site pain
• sore throat and irritated nasal passages		Lyumjev at mealtime, with basal insulin:
• sore throat and irritated nasal passages (nasopharyngitis)
• upper respiratory tract infection
HumalogHumalog alone:
• sore throat
• irritated nasal passages
• headache
• pain
• increased cough
• infection
• nausea
• fever
• abdominal pain
• weakness (asthenia)
• bronchitis
• diarrhea
• muscle pain
• urinary tract infection (UTI)		Humalog alone:
• headache
• pain
• infection
• sore throat
• irritated nasal passages
FiaspFiasp at mealtime, with insulin detemir:
• sore throat and irritated nasal passages (nasopharyngitis)
• upper respiratory tract infection
• nausea
• diarrhea
• back pain		Fiasp, with insulin glargine:
• UTI

Note: Learn more about insulin types used in these studies: basal insulin, insulin detemir, and insulin glargine.

Consider the following important information before starting treatment with Lyumjev.

Before using Lyumjev, discuss your health history with your doctor. Lyumjev may not be right for you if you have certain medical conditions or other factors affecting your health. Be sure to talk with your doctor if any of the following apply to you:

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.