Insulin allergies, although rare, are unpredictable and can occur at any time during treatment. Symptoms of an allergic reaction can be immediate or can appear after the patient has been taking the medication for longer than a week. Reactions can either be local or affect two or more body systems (anaphylaxis).

The signs and symptoms of a local allergic reaction to insulin include:

• Dents under the skin at the injection site
• Swelling at the injection site
• Persistent or temporary redness at the injection site
• Itching at the injection site
• Clusters of small bumps that are similar to hives

Local reactions occur only in the area where the insulin was injected. These reactions usually appear within 30 to 60 minutes and usually disappear within a few days to a few weeks. Patients should contact their physician when they believe they are suffering a local allergic reaction to their insulin.

In severe cases an anaphylactic reaction could occur. Anaphylaxis is a rare, severe allergic reaction that affects two or more body systems. It can affect the skin, lungs, nose, throat, gastrointestinal tract and heart. Without prompt emergency treatment, anaphylaxis can quickly progress to anaphylactic shock and become deadly.

Symptoms of anaphylaxis generally occur immediately after exposure to the allergen. However, it can take as long as several hours after exposure before signs of anaphylaxis appear. The more rapidly symptoms appear, the more severe they are likely to become.

Early signs and symptoms include:

• Severe itching of the eyes and face
• Anxiety
• Palpitations
• Rapid or weak pulse
• Swelling of the throat or tongue
• Slurred speech
• Difficulty swallowing
• Coughing, choking, wheezing or difficulty breathing
• Bluish tint to skin (cyanosis), including lips or nail beds
• Nasal congestion
• Red or swelling skin
• Hives (including on the lips, eyelids, throat and tongue)
• Abdominal cramps
• Diarrhea
• Nausea or vomiting
• Drop in blood pressure

Without immediate emergency treatment, anaphylaxis can quickly progress to anaphylactic shock and become deadly. More advanced signs and symptoms include:

• Collapse or loss of consciousness
• Convulsions
• Loss of bladder control
• Shock
• Stroke
• Cardiac arrest
• Respiratory arrest

Patients should ask their physician what steps to take if they recognize any of these symptoms. A common recommendation is to seek emergency treatment as soon as an insulin-using diabetic person experiences any of the signs or symptoms of a systemic allergic reaction.