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What You Need To Know About The Side Effects of Insulin

Expertly reviewed by Dexter Macalintal, MD · Internal or General Medicine

Written by Hello Bacsi · Updated Apr 04, 2022

What You Need To Know About The Side Effects of Insulin

You may never have to worry about the side effects of insulin when using it to control your diabetes. But, there is still a chance that the drug may affect you negatively. Insulin might lead to allergic reactions or other uncomfortable signs and symptoms. Learn more about the possible side effects of insulin here. 

Allergic Reactions To Insulin: Symptoms and Severity

A small number of patients taking insulin have experienced allergic reactions. How do you identify these reactions? 

If, after injecting insulin , you notice that the skin around the injection site is swollen or red, has a rash, itches, and your face and lips start to swell, it’s most likely an insulin allergy.

If the side effects of insulin are life-threatening, as evidenced by  symptoms, such as swollen tongue , tightness in the chest, shortness of breath, dizziness, or fainting, you should be hospitalized immediately for emergency care and treatment.

However, please note that allergy to insulin is very rare.

Hypoglycemia: The Most Common Side Effect Of Insulin

Hypoglycemia is the most common and serious adverse effect of insulin, occurring in approximately 16% of patients with type 1 diabetes and 10% of patients with type 2 diabetes.

Severe hypoglycemia usually presents initially with confusion, sweating, and heart palpitations. More serious cases may result in convulsions, coma, neurological impairment, and even death.

If you’re at risk for low blood sugar, you may need to monitor your blood or urine sugar regularly

The risk of hypoglycemia is higher if you use too much insulin or take insulin injections continuously. It may also occur when you take the correct amount of insulin at the appropriate time, but do not consume enough food. 

Diabetes and its treatments affect your blood sugar a lot. The goal is to avoid very low (hypoglycemia) or very high ( hyperglycemia ) sugar levels.

Recognizing and Treating Hypoglycemia

You may experience low blood sugar after using insulin. Because insulin’s job is to lower your blood sugar, it has the ability to work so well that blood sugar drops too much. 

Hence, it is important to learn to recognize the symptoms of hypoglycemia immediately. Some of the signs and symptoms include shakiness, hunger, irritability, sweating, and pale skin. 

You can check your blood sugar level with a blood glucose meter . If you see a drop in blood sugar, use fast-acting carbohydrates as advised by your doctor. Fast-acting carbohydrates include fruit juices, candies, cookies, raisins, and regular soft drinks.

People who have severe hypoglycemia and cannot eat or drink anything need urgent glucagon injections.

Your doctor and diabetes team are your best resource to help you learn how to recognize the side effects of insulin and manage allergies effectively.

Other Side Effects Of Insulin

Other insulin side effects include weight gain, symptoms caused by interactions with other medications, headaches and nausea.

Weight gain may be due to the body’s more efficient use of calories during insulin treatment. Patients on high-dose insulin therapy are more likely to experience weight gain. Discuss with your doctor if you need to change your diet plan and exercise routine. 

Some people experience dimples or thickening of the skin at the injection site. This is why it’s important to rotate the sites of injection.

In addition, taking certain diabetes medications while taking insulin can increase your risk of serious heart problems. So tell your doctor if you are taking any other medications. Insulin should also be used with caution in people with pre-existing liver, kidney or heart failure.

Also, each type of insulin may have its own set of side effects. When you start using a new insulin, read the patient information to identify common side effects of that insulin.

Since reactions to insulin are uncommon, you should be aware of potential side effects. Knowing how to recognize if your body is having an allergic reaction or low blood sugar after an insulin shot is important to your health as it allows you to take action immediately. 

Key Takeaways

Although most people who use insulin do not experience significant side effects, you still need to be aware of potential complications in case they do occur. It would also be a good practice to follow up with your diabetes team and discuss probable side effects of the medications you are taking aside from insulin. Lastly, schedule a visit with your registered nutritionist-dietitian for necessary adjustments in your dietary plans.

Learn more about Diabetes here.


Hello Health Group does not provide medical advice, diagnosis or treatment.

Expertly reviewed by

Dexter Macalintal, MD

Internal or General Medicine

Written by Hello Bacsi · Updated Apr 04, 2022

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