Medically reviewed on June 25, 2018
What is regular insulin?
Insulin is a hormone that works by lowering levels of glucose (sugar) in the blood. Regular insulin is a short-acting insulin that starts to work within 30 minutes after injection, peaks in 2 to 3 hours, and keeps working for up to 8 hours.
Regular insulin may also be used for purposes not listed in this medication guide.
Before taking this medicine
You should not use Humulin R if you are allergic to insulin, or if you are having an episode of hypoglycemia (low blood sugar).
Regular insulin is not approved for use by anyone younger than 2 years old. Regular insulin should not be used to treat type 2 diabetes in a child of any age.
To make sure insulin is safe for you, tell your doctor if you have:
liver or kidney disease; 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.
Follow your doctor's instructions about using insulin if you are pregnant or breast-feeding a baby. Blood sugar control is very important during pregnancy, and your dose needs may be different during each trimester of pregnancy. Your dose needs may also be different while you are breast-feeding.
How should I use regular insulin?
Follow all directions on your prescription label. Do not use this medicine in larger or smaller amounts or for longer than recommended.
Insulin is injected under the skin. You may be shown how to use injections at home. Do not give yourself this medicine if you do not understand how to use the injection and properly dispose of used needles and syringes.
Your care provider will show you the best places on your body to inject regular insulin. Use a different place each time you give an injection. Do not inject into the same place two times in a row.
After using regular insulin, you should eat a meal within 30 minutes.
Regular insulin must not be given with an insulin pump. Do not inject regular insulin into a vein or a muscle.
Never share a syringe with another person, even if the needle has been changed. Sharing syringes can allow infections or disease to pass from one person to another.
Use a disposable needle and syringe only once. Follow any state or local laws about throwing away used needles and syringes. Use a puncture-proof "sharps" disposal container (ask your pharmacist where to get one and how to throw it away). Keep this container out of the reach of children and pets.
Low blood sugar (hypoglycemia) can happen to everyone who has diabetes. Symptoms include headache, hunger, sweating, irritability, dizziness, nausea, fast heart rate, and feeling anxious or shaky. To quickly treat low blood sugar, always keep a fast-acting source of sugar with you such as fruit juice, hard candy, crackers, raisins, or non-diet soda.
Your doctor can prescribe a glucagon emergency injection kit to use in case you have severe hypoglycemia and cannot eat or drink. Be sure your family and close friends know how to give you this injection in an emergency.
Also watch for signs of high blood sugar (hyperglycemia) such as increased thirst or urination, blurred vision, headache, and tiredness.
Blood sugar levels can be affected by stress, illness, surgery, exercise, alcohol use, or skipping meals. Ask your doctor before changing your insulin dose or schedule.
Regular insulin is only part of a complete treatment program that may also include diet, exercise, weight control, regular blood sugar testing, and special medical care. Follow your doctor's instructions very closely.
Keep this medicine in its original container protected from heat and light. Do not draw insulin from a vial into a syringe until you are ready to give an injection. Do not freeze insulin or store it near the cooling element in a refrigerator. Throw away any insulin that has been frozen.
Storing unopened (not in use) regular insulin:
Refrigerate and use until expiration date; or
Store at room temperature and use within 42 days.
Storing opened (in use) regular insulin:
Store at room temperature and use within 42 days.
Do not use the medicine if it looks cloudy, has changed colors, or has any particles in it. Call your pharmacist for new medicine.
Read all patient information, medication guides, and instruction sheets provided to you. Ask your doctor or pharmacist if you have any questions.
Wear a diabetes medical alert tag in case of emergency. Any medical care provider who treats you should know that you have diabetes.
What happens if I miss a dose?
Use the missed dose as soon as you remember. Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra medicine to make up the missed dose.
Keep insulin on hand at all times. Get your prescription refilled before you run out of medicine completely.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. Insulin overdose can cause life-threatening hypoglycemia. Symptoms include drowsiness, confusion, blurred vision, numbness or tingling in your mouth, trouble speaking, muscle weakness, clumsy or jerky movements, seizure (convulsions), or loss of consciousness.
What should I avoid while using regular insulin?
Do not change the brand of insulin or syringe you are using without first talking to your doctor or pharmacist. Some brands of insulin and syringes are interchangeable, while others are not. Your doctor and/or pharmacist know which brands can be substituted for one another.
Insulin can cause low blood sugar. Avoid driving or operating machinery until you know how Humulin R will affect you.
Avoid medication errors by always checking the medicine label before injecting your insulin.
Avoid drinking alcohol. It can cause low blood sugar and may interfere with your diabetes treatment.
Regular insulin side effects
Get emergency medical help if you have signs of insulin allergy: 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:
Common side effects may include:
low blood sugar;
swelling in your hands or feet;
weight gain; 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.
See also: Side effects (in more detail)
What other drugs will affect regular insulin?
Many other medicines can affect your blood sugar, and some medicines can increase or decrease the effects of insulin. Some drugs can also cause you to have fewer symptoms of hypoglycemia, making it harder to tell when your blood sugar is low. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using. This includes prescription and over-the-counter medicines, vitamins, and herbal products.
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Copyright 1996-2018 Cerner Multum, Inc. Version: 8.01.
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