Get emergency medical help if you have signs of insulin allergy to Humalog: redness or swelling where an injection was given, itchy skin rash over the entire body, trouble breathing, fast heartbeats, feeling like you might pass out, or swelling in your tongue or throat.
Call your doctor at once if you have:
weight gain, swelling in your hands or feet, feeling short of breath;
low blood sugar - headache, hunger, sweating, irritability, dizziness, fast heart rate, and feeling anxious or shaky; or
low potassium - leg cramps, constipation, irregular heartbeats, fluttering in your chest, increased thirst or urination, numbness or tingling, muscle weakness or limp feeling.
Common Humalog side effects may include:
low blood sugar;
weight gain;
swelling in your hands or feet;
itching; or
thickening or hollowing of the skin where you injected the medicine.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
 Humalog side effects (more detail)
Before taking this medicine
You should not use Humalog if you are allergic to insulin, or if you are having an episode of hypoglycemia (low blood sugar).
Humalog should not be given to a child younger than 3 years old. Humalog should not be used to treat type 2 diabetes in a child of any age.
To make sure Humalog is safe for you, tell your doctor if you have ever had:
liver or kidney disease;
heart problems; or
low levels of potassium in your blood (hypokalemia).
Tell your doctor if you also take pioglitazone or rosiglitazone (sometimes contained in combinations with glimepiride or metformin). Taking certain oral diabetes medicines while you are using insulin may increase your risk of serious heart problems.
Tell your doctor if you are pregnant or breastfeeding.
Follow your doctor's instructions about using Humalog if you are pregnant or you become pregnant. Controlling diabetes is very important during pregnancy, and having high blood sugar may cause complications in both the mother and the baby.
