Tresiba Side Effects: Hypoglycemia, Weight Gain, Headache

Tresiba (Flextouch) is a long-acting insulin by the brand name insulin degludec. 

Insulin degludec is a medication used to treat diabetes in people who are one year old and above. 

Tresiba is a subcutaneous injection that reduces the amount of sugar in your blood. 

If you are taking Tresiba, you may suffer from some side effects. 

Individual responses to side effects may vary, and the severity may depend on factors such as age, Tresiba dosage, other medications, and existing medical conditions.

Let’s take a look at the most common adverse effects of Tresiba and ways to prevent or reduce the symptoms. 

Side effects of Tresiba to watch out for

Some side effects of Tresiba may be minor, while others may be more severe. Let’s take a look at the possible side effects you may experience.

1) Hypoglycemia

Studies suggest that hypoglycemia is reported as one of the common side effects in insulin users. Tresiba can cause a decrease in blood sugar in both type 1 and type 2 diabetes. 

Hypoglycemia is a serious side effect that can be fatal if it isn’t treated. 

If you are on Tresiba, you must learn to recognize the signs and symptoms of hypoglycemia, which are:

  • Headache
  • Dizziness
  • Sweating
  • Shakiness
  • Increased heartbeat
  • Hunger 
  • Weakness
  • Irritable and anxiety
  • Confusion
  • Loss of consciousness fits, or coma in severe cases

If you suspect your blood sugar is low, check your blood sugar levels with a blood glucose monitor.

2) Skin reactions

When taking insulin, you may experience skin reactions at the injection site, such as:

  • Itching
  • Erythema (redness around the area)
  • Hematoma or swelling
  • Lipohypertrophy
  • Cutaneous amyloidosis

To avoid these side effects from insulin degludec, try to rotate between different areas you inject, like your abdomen, thighs, and upper arms. 

3) Hypokalemia

Insulin degludec can cause a shift of the electrolyte potassium in your body. Potassium leaves your blood and enters your cells. This can leave a deficit in your blood potassium levels. 

As a result, you may experience the following symptoms:

  • Weakness
  • Muscle cramps or twitching
  • Fatigue
  • Thirst
  • Irregular heartbeat
  • Respiratory paralysis
  • Death

Speak to your doctor if you notice any of these signs of hypokalemia.

4) Weight gain

Putting on weight is a common side effect associated with insulin. Insulin encourages your body to store up more fat in your cells, which can result in weight gain.

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5) Allergy (hypersensitivity reaction)

In rare cases, you may have a hypersensitivity reaction to Tresiba or an ingredient in it. Visit the nearest emergency unit if you experience signs of hypersensitivity. This could be:

  • Swelling of the face, mouth, tongue, and throat
  • Trouble breathing
  • Increase heartbeat
  • Pruritus (itching) and rashes

You may be having a life-threatening hypersensitivity reaction called anaphylaxis.

6) Swelling, especially on the hands and feet

Tresiba may cause fluid to accumulate in your tissues. This causes swelling in your hands and feet, a condition called peripheral edema. 

People who have type 2 diabetes and are on Tresiba are more likely to get edema. 

7) Other side effects of Insulin degludec

Some people may experience:

  • Inflammation in their respiratory tract, such as nasopharyngitis, sinusitis, upper respiratory tract infection, like a cold
  • Itching, redness, or rash at the injection site
  • Headache
  • Diarrhea

Most of these side effects of Tresiba go away on their own after a few days or weeks. But if they persist or become worse, speak with a healthcare professional. 

How to reduce adverse reactions from Tresiba

Here are some tips to manage the side effects of Tresiba:

Get a blood glucose monitor 

This will help you check your blood sugar levels. It will help you to know whether your blood sugar is well controlled or not. You can also detect hypoglycemia and treat it in time. 

Inform your doctor about any concurrent medications while using Tresiba

Some medications may worsen the side effects of Tresiba.  Tell your doctor about any drug you are taking. 

Avoid alcohol

Alcohol can increase your risk of hypoglycemia, reducing your blood sugar levels. It can also prevent your liver from regulating your sugar levels. 

It is best to abstain from alcohol while on Tresiba.

Let your doctor know if you have another condition 

You should tell your doctor about any other conditions you may have, like kidney or liver problems. These conditions may affect your blood sugar and increase the risk of hypoglycemia.

Pay attention to the dose you are taking

You need to pay attention to the Tresiba dose you are taking. Make sure you take Flextouch exactly as directed by your healthcare provider. If you have any doubts, speak to your doctor or pharmacist. 

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How long do side effects from insulin degludec last?

Commonly, Tresiba side effects resolve within a few days or weeks. Most of them disappear on their own. 

If your side effects do not go away or become severe, speak to your doctor for advice.

Are there any long-term side effects of Flextouch?

Some potential long-term side effects of insulin degludec are:

  • Edema (swelling of the hands and legs). If you take Tresiba with rosiglitazone, you may develop heart failure. 
  • Hypoglycemia
  • Hyperglycemia
  • Hypokalemia
  • Allergic reactions, which may be severe

If any of these side effects have been persistent, please contact your doctor for help.

Potential side effects of Tresiba in elderly patients

Tresiba is generally safe to use in older people, but you may experience the following side effects: 


Due to older age, it may be difficult to notice certain side effects, especially hypoglycemia. You must watch your blood sugar level regularly to avoid hypoglycemia.

Organ damage

Older adults tend to handle drugs slower than younger people. They are more at risk of having organ damage like kidney or liver injury because of their age. 

If any of these are present, they may have problems when they take some drugs. Patients should be closely monitored as a precaution. 

The dosages may need to be adjusted in cases where there is a problem with certain organs. 

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Side effects of stopping Tresiba

If you stop using Tresiba, your blood sugar levels may increase, causing hyperglycemia. If this is not well controlled, you may develop diabetic ketoacidosis. 

In ketoacidosis, there is too much acid in your blood and urine, which is dangerous and can be severe.

Please talk to your doctor first before you stop taking Tresiba. 


Tresiba is a brand name for insulin degludec. It is described as a long-acting insulin taken once a day to help regulate high blood sugar, according to its intended use.

Some individuals may experience side effects while using it. Some Tresiba side effects may be mild, like headache, weight gain, or skin changes where you inject the medicine. These usually resolve after a couple of days.

Sometimes, you may experience more serious side effects from Flextouch. The most common one is low blood sugar or hypoglycemia. 

If you are using flextouch, you need to learn to recognize the side effects so that you may take precautions to prevent hypoglycemia and other side effects. 

Always speak to your healthcare provider if you have questions or symptoms you are unsure about.

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  1. Kahara T, Kawara S, Shimizu A, Hisada A, Noto Y, Kida H. Subcutaneous hematoma due to frequent insulin injections in a single site. Intern Med. 2004 Feb;43(2):148-9. doi: 10.2169/internalmedicine.43.148. PMID: 15005260.
  2. Aung T, Noakes R, Murrell DF, Daniel BS, Kelati A. Primary cutaneous amyloidosis: A review of the available studies and gaps in data. Australas J Dermatol. 2023 May;64(2):e121-e124. doi: 10.1111/ajd.14012. Epub 2023 Feb 24. PMID: 36825814.
  3. Access FDA. TRESIBA® (insulin degludec injection) for subcutaneous use.

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