If you have diabetes, your doctor might suggest Tresiba (insulin degludec) as a treatment option for you.

Tresiba is a prescription medication. It’s used long term to manage blood sugar levels in adults and some children with type 1 or type 2 diabetes.

Tresiba is a type of insulin. It comes as a liquid solution that you’ll inject under your skin. For more information about Tresiba, see this in-depth article.

Like other drugs, Tresiba can cause mild or serious side effects. Keep reading to learn more.

Some people may experience mild or serious side effects during their Tresiba treatment.

More common side effects that have been reported with Tresiba include:

  • hypoglycemia (low blood sugar)
  • rash or itching at the injection site*
  • weight gain*

These side effects can vary depending on the condition the drug is being used to treat.

Like all medications, Tresiba can cause rare side effects. Examples of rare side effects that have been reported with Tresiba include:

* To learn more about this side effect, see “Side effects explained” below.

Examples of mild side effects that have been reported with Tresiba include:

* To learn more about this side effect, see “Side effects explained” below.

In most cases, these side effects should be temporary. And some may be easily managed, too. But if you have any symptoms that are ongoing or that bother you, talk with your doctor or pharmacist. And don’t stop using Tresiba unless your doctor recommends it.

Tresiba may cause mild side effects other than those listed above. See the Tresiba prescribing information.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Tresiba, visit MedWatch.

Serious side effects that have been reported with Tresiba include:

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

* To learn more about this side effect, see “Side effects explained” below.

Learn the answers to some frequently asked questions about Tresiba’s side effects.

Could Tresiba cause eye-related side effects?

No. Eye-related side effects weren’t reported in studies of Tresiba.

But people with diabetes have a higher risk for developing eye problems, such as:

If you have diabetes, it’s important to get regular eye exams. If eye-related problems are found early, many effective treatment options are available. Also, managing your blood sugar levels may help prevent complications of diabetes, including eye problems.

Will I experience hair loss during my Tresiba treatment?

If you experience hair loss with Tresiba, it’s probably not caused by the drug. Hair loss wasn’t a side effect reported in people taking Tresiba in studies.

But diabetes itself can lead to hair loss and slowed hair growth. This is because high blood sugar levels can damage your blood vessels over time. Damaged blood vessels may not deliver enough oxygen to support hair growth.

If you have questions or concerns about hair loss while you’re using Tresiba, talk with your doctor.

Is stomach pain a side effect of Tresiba?

No. Abdominal (belly) pain isn’t a side effect of Tresiba. But you could experience injection-site reactions where you inject the drug, including in your abdomen. These reactions could include pain, redness or discoloration, swelling, or itchiness.

If you experience pain in your abdomen after injecting Tresiba, talk with your doctor about ways to prevent or treat it.

Could my heart rate be affected by using Tresiba?

Tresiba doesn’t directly cause heart rate changes. But if you develop hypokalemia (low potassium levels), your heart could be affected. Hypokalemia is a serious side effect that’s possible with all insulins, including Tresiba.

For more details about this, see the “Side effects explained” section below regarding hypokalemia.

Does Tresiba cause shortness of breath?

No, shortness of breath isn’t a direct side effect of Tresiba. But it’s a possible symptom of heart failure.

Heart failure has been reported when Tresiba is used with a type of diabetes drug called a thiazolidinedione. Examples of thiazolidinediones include Actos (pioglitazone) and Avandia (rosiglitazone).

If you’re prescribed other diabetes drugs to take with Tresiba, talk with your doctor to make sure they’re safe to use together.

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

Weight gain

Using insulin, including Tresiba, can cause weight gain in some people. Weight gain was a common side effect reported by people using Tresiba in studies.

What might help

It’s important to monitor your weight during your Tresiba treatment. Changes in your weight might mean that your doctor needs to adjust your Tresiba dosage.

If you’re concerned about weight gain during your Tresiba treatment, here are some tips that could help you reach or maintain a moderate weight.

  • Track your calories. Consuming more calories than you burn can lead to high blood sugar levels and increased fat storage. Consider using a calorie-tracking app or a journal to log the calories you eat. Keeping track of your foods and portion sizes can help prevent you from taking in too many calories.
  • Get regular exercise. Exercise can help you burn calories and manage your blood sugar levels. If you’re beginning a new fitness routine, it’s best to start small and set realistic goals. And talk with your doctor before starting a new exercise routine.
  • Meet with a professional. Your doctor may be able to refer you to a registered dietitian or certified nutritionist. They can provide nutritional counseling that’s customized for your specific needs.

If you have concerns about gaining weight during your Tresiba treatment, talk with your doctor.

Injection-site reactions

Tresiba may cause injection-site reactions. This side effect is possible with all insulins, but it wasn’t commonly reported in people using Tresiba in studies. The following side effects can occur at or around the injection site:

  • bruising
  • pain
  • bleeding
  • rash
  • swelling
  • itching
  • warmth
  • redness or discoloration

Although less common, lipodystrophy (thickened skin at injection site) can also develop. This appears as lumps or pits at the injection site due to fat accumulation under the skin. It’s more likely to develop if you repeatedly inject the drug at the same site.

What might help

To help prevent or reduce injection-site reactions, be sure to rotate your injection sites. Tresiba may be injected under the skin of your thighs, upper arms, or abdomen (belly). It’s important to avoid using the same injection site multiple times in a row.

When choosing an injection site, avoid areas where your skin is damaged, scarred, tender, bruised, thickened, or has lumps.

You’ll use alcohol to clean your skin before each insulin injection. Be sure to let the alcohol air-dry before injecting Tresiba. This can help reduce pain or stinging.

If you’re concerned about injection-site side effects with Tresiba, talk with your doctor or pharmacist.

Hypokalemia

Although it’s less common, Tresiba can cause hypokalemia (low potassium levels).

Certain other medications can also lower your potassium levels. Using these medications with Tresiba can raise your risk for this side effect. Examples of these medications include certain diuretic medications (water pills) such as hydrochlorothiazide.

Symptoms of hypokalemia may include:

What might help

While you’re using any type of insulin, your doctor will monitor your potassium levels with blood tests.

If your potassium levels become low, your doctor may recommend changes to your treatment plan. They may also prescribe a medication that’ll bring your potassium levels up to normal, such as K-Dur (potassium chloride).

If you have questions or concerns about hypokalemia with Tresiba, talk with your doctor.

Allergic reaction

Like most drugs, Tresiba can cause an allergic reaction in some people. In studies, allergic reactions were rarely reported with Tresiba, but they did occur.

Symptoms of an allergic reaction can be mild or serious and can include:

  • skin rash
  • itchiness
  • flushing (warmth or redness/deepening of skin color for a brief time)
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

In studies of Tresiba, the following symptoms were also reported as related to allergic reactions:

  • swelling of the tongue and lips
  • diarrhea
  • nausea
  • feeling tired
  • itchiness
  • hives (raised skin welts)

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 an over-the-counter oral antihistamine, such as Benadryl (diphenhydramine), or a topical product, like hydrocortisone cream, to manage your symptoms.

If your doctor confirms you had a mild allergic reaction to Tresiba, they’ll decide if you should continue using it.

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

If your doctor confirms you had a serious allergic reaction to Tresiba, they may have you switch to a different treatment.

Keeping track of side effects

During your Tresiba treatment, consider keeping notes on any side effects you’re having. Then, you can share this information with your doctor. This is especially helpful to do when you first start taking new drugs or using a combination of treatments.

Your side effect notes can include things like:

  • what dose of drug you were taking when you had the side effect
  • how soon after starting that dose you had the side effect
  • what your symptoms were from the side effect
  • how it affected your daily activities
  • what other medications you were also taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help your doctor learn more about how the drug affects you. And your doctor can use this information to adjust your treatment plan if needed.

Tresiba may not be right 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 Tresiba. The list below includes factors to consider.

Liver or kidney disease. If you have certain types of liver disease or kidney disease, this could raise your risk for hypoglycemia from Tresiba. If you’ve had problems with your kidney or liver, talk with your doctor before using Tresiba. They may adjust your dose of Tresiba or monitor you more closely during your treatment.

Allergic reaction. If you’ve had an allergic reaction to Tresiba or any of its ingredients, you should not take Tresiba. Ask your doctor about other medications that might be better options for you.

Alcohol use and Tresiba

Drinking alcohol during your Tresiba treatment may increase your risk for hypoglycemia (low blood sugar).

Alcohol can affect your blood sugar in the following ways:

  • It can prevent your liver from regulating your blood sugar.
  • It can cause hypoglycemia.

Insulins, including Tresiba, can also cause hypoglycemia. According to the American Diabetes Association, drinking alcohol while using insulin medications such as Tresiba can raise your risk for this side effect.

Because of this risk, talk with your doctor about how much (if any) is safe for you to drink while using Tresiba.

Pregnancy and breastfeeding while taking Tresiba

It’s unknown if Tresiba is safe to use during pregnancy or while breastfeeding.

If you’re pregnant or breastfeeding, or are planning to become pregnant or to breastfeed, talk with your doctor. It’s important to manage your blood sugar during this time. Your doctor can explain the risks and benefits of Tresiba and determine the best treatment option for you.

Tresiba is a type of insulin used to control blood sugar levels in adults and some children with diabetes. For most people, the side effects of Tresiba are mild or easily managed. But serious side effects can occur.

If you have questions about Tresiba’s side effects, talk with your doctor or pharmacist. If you’re not sure where to start, here are some suggestions to consider asking your doctor:

  • Will my other diabetes medications increase my risk for side effects from Tresiba?
  • Do my other health conditions put me at a higher risk for side effects?
  • Will my risk for having side effects be reduced with a lower dosage of Tresiba?
  • Are there any injection tips that would lower my risk for injection-site side effects?

If you have type 2 diabetes, sign up for Healthline’s type 2 diabetes newsletter to get helpful tips on managing your condition.

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 other 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.