Humulin R may lead to various side effects, some of which can be serious. These include:
1. Low Blood Sugar (Hypoglycemia): Symptoms of low blood sugar may occur suddenly and can range from mild to severe. Common signs of mild to moderate hypoglycemia include sweating, drowsiness, dizziness, fast heart rate, tremors, hunger, restlessness, tingling in extremities, lightheadedness, headache, and trouble concentrating. Severe hypoglycemia can cause confusion, loss of consciousness, seizures, coma, and even be life-threatening. It’s crucial to be aware of the symptoms and follow your healthcare provider’s guidance on managing low blood sugar.
2. Serious Allergic Reactions: In rare cases, individuals may experience severe allergic reactions to Humulin R, which require immediate medical attention. Symptoms can include a widespread rash, shortness of breath, wheezing, rapid heart rate, sweating, and feeling faint.
3. Low Potassium (Hypokalemia): Your healthcare provider may perform blood tests to monitor your potassium levels while using Humulin R.
Common, less severe side effects of Humulin R may include:

• Skin thickening or pitting at the injection site (lipodystrophy). To minimize these skin changes, it’s recommended to rotate injection sites and avoid injecting into areas with existing skin changes.
• Injection site reactions, such as redness, swelling, and itching. If these reactions persist, inform your healthcare provider.
• Weight gain.
• Swelling due to fluid retention.

If you experience any side effects that are bothersome or persistent, discuss them with your healthcare provider. Keep in mind that this list may not encompass all potential side effects of Humulin R. For more detailed information, consult your healthcare provider or pharmacist.