Isophane Insulin (NPH) Injection

NPH insulin (isophane) is a medication that treats diabetes. It increases levels of insulin in your body to decrease your blood sugar. This is an immediate-acting insulin. A healthcare provider will teach you how to inject this medication under your skin. The brand names of this product are Humulin® and Novolin®.

What is this medication?

ISOPHANE INSULIN (NPH) (EYE soe fane IN su lin) treats diabetes. It works by increasing insulin levels in your body, which decreases your blood sugar (glucose). It belongs to a group of medications called intermediate-acting insulins. Changes to diet and exercise are often combined with this medication.

This medicine may be used for other purposes; ask your health care provider or pharmacist if you have questions.

COMMON BRAND NAME(S): Humulin N, Novolin N, ReliOn

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What should I tell my care team before I take this medication?

They need to know if you have any of these conditions:

  • Episodes of hypoglycemia
  • Eye disease, vision problems
  • Kidney disease
  • Liver disease
  • An unusual or allergic reaction to insulin, metacresol, other medications, foods, dyes, or preservatives
  • Pregnant or trying to get pregnant
  • Breast-feeding

How should I use this medication?

Insulin is for injection under the skin. Use exactly as directed. It is important to follow the directions given to you by your care team. You will be taught how to use this medication and how to adjust doses for activities and illness. Do not use more insulin than prescribed. Do not use more or less often than prescribed.

Always check the appearance of your insulin before using it. This medication should be white and cloudy. Do not use it if it is not uniformly cloudy after mixing.

It is important that you put your used needles and syringes in a special sharps container. Do not put them in a trash can. If you do not have a sharps container, call your pharmacist or care team to get one.

If you use a pen, be sure to take off the outer needle cover before using the dose.

This medication comes with INSTRUCTIONS FOR USE. Ask your pharmacist for directions on how to use this medication. Read the information carefully. Talk to your pharmacist or care team if you have questions.

Talk to your care team regarding the use of this medication in children. While this medication may be prescribed for children for selected conditions, precautions do apply.

Overdosage: If you think you have taken too much of this medicine contact a poison control center or emergency room at once.

NOTE: This medicine is only for you. Do not share this medicine with others.

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What if I miss a dose?

It is important not to miss a dose. Your care team should discuss a plan for missed doses with you. If you do miss a dose, follow their plan. Do not take double doses.

What may interact with this medication?

  • Alcohol containing beverages
  • Aspirin and aspirin-like medications
  • Beta-blockers like atenolol, metoprolol, propranolol
  • Chloramphenicol
  • Chromium
  • Clonidine
  • Diuretics
  • Female hormones, like estrogens or progestins and birth control pills
  • Guanethidine
  • Heart medications
  • Isoniazid
  • Male hormones or anabolic steroids
  • Medications for weight loss
  • Medications for allergies, asthma, cold, or cough
  • Medications for mental problems
  • Medications called MAO Inhibitors like Nardil, Parnate, Marplan, Eldepryl
  • Niacin
  • NSAIDs, medications for pain and inflammation, like ibuprofen or naproxen
  • Other medications for diabetes, like glyburide, glipizide, or glimepiride
  • Pentamidine
  • Phenytoin
  • Probenecid
  • Quinolone antibiotics like ciprofloxacin, levofloxacin, ofloxacin
  • Reserpine
  • Some herbal dietary supplements
  • Steroid medications like prednisone or cortisone
  • Thyroid medication

This list may not describe all possible interactions. Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Also tell them if you smoke, drink alcohol, or use illegal drugs. Some items may interact with your medicine.

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What should I watch for while using this medication?

Visit your care team for regular checks on your progress.

A test called the HbA1C (A1C) will be monitored. This is a simple blood test. It measures your blood sugar control over the last 2 to 3 months. You will receive this test every 3 to 6 months.

Learn how to check your blood sugar. Learn the symptoms of low and high blood sugar and how to manage them.

Always carry a quick-source of sugar with you in case you have symptoms of low blood sugar. Examples include hard sugar candy or glucose tablets. Make sure others know that you can choke if you eat or drink when you develop serious symptoms of low blood sugar, such as seizures or unconsciousness. They must get medical help at once.

Tell your care team if you have high blood sugar. You might need to change the dose of your medication. If you are sick or exercising more than usual, you might need to change the dose of your medication.

Do not skip meals. Ask your care team if you should avoid alcohol. Many nonprescription cough and cold products contain sugar or alcohol. These can affect blood sugar.

Make sure that you have the right kind of syringe for the type of insulin you use. Try not to change the brand and type of insulin or syringe unless your care team tells you to. Switching insulin brand or type can cause dangerously high or low blood sugar. Always keep an extra supply of insulin, syringes, and needles on hand. Use a syringe one time only. Throw away syringe and needle in a closed container to prevent accidental needle sticks.

Insulin pens and cartridges should never be shared. Even if the needle is changed, sharing may result in passing of viruses like hepatitis or HIV.

Each time you get a new box of pen needles, check to see if they are the same type as the ones you were trained to use. If not, ask your care team to show you how to use this new type properly.

Wear a medical ID bracelet or chain, and carry a card that describes your disease and details of your medication and dosage times.

What side effects may I notice from receiving this medication?

Side effects that you should report to your care team as soon as possible:

  • Allergic reactions—skin rash, itching, hives, swelling of the face, lips, tongue, or throat
  • Low blood sugar (hypoglycemia)—tremors or shaking, anxiety, sweating, cold or clammy skin, confusion, dizziness, rapid heartbeat
  • Low potassium level—muscle pain or cramps, unusual weakness or fatigue, fast or irregular heartbeat, constipation

Side effects that usually do not require medical attention (report to your care team if they continue or are bothersome):

  • Lipodystrophy—hardening or scarring of tissue at injection site
  • Pain, redness, or irritation at injection site
  • Weight gain

This list may not describe all possible side effects. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Where should I keep my medication?

Keep out of the reach of children and pets.

Unopened Vials:

Humulin N Vials: Store in a refrigerator between 2 and 8 degrees C (36 and 46 degrees F) or at room temperature up to 30 degrees C (86 degrees F). Do not freeze or use if the insulin has been frozen. Protect from light and excessive heat. If stored at room temperature, the vial must be discarded after 31 days. Throw away any unopened and unused medication that has been stored in the refrigerator after the expiration date.

Novolin N Vials: Store in a refrigerator between 2 and 8 degrees C (36 and 46 degrees F) or at room temperature up to 25 degrees C (77 degrees F). Do not freeze or use if the insulin has been frozen. Protect from light and excessive heat. If stored at room temperature, the vial must be discarded after 42 days. Throw away any unopened and unused medication that has been stored in the refrigerator after the expiration date.

Unopened Pens:

Humulin N KwikPens: Store in a refrigerator between 2 and 8 degrees C (36 and 46 degrees F) or at room temperature up to 30 degrees C (86 degrees F). Do not freeze or use if the insulin has been frozen. Protect from light and excessive heat. If stored at room temperature, the pen must be discarded after 14 days. Throw away any unopened and unused medication that has been stored in the refrigerator after the expiration date.

Novolin N FlexPens: Store in a refrigerator between 2 and 8 degrees C (36 and 46 degrees F) or at room temperature up to 30 degrees C (86 degrees F). Do not freeze or use if the insulin has been frozen. Protect from light and excessive heat. If stored at room temperature, the pen must be discarded after 28 days. Throw away any unopened and unused medication that has been stored in the refrigerator after the expiration date.

Vials that you are using:

Humulin N vials: Store in the refrigerator or at room temperature up to 30 degrees C (86 degrees F). Do not freeze. Keep away from heat and light. Throw the opened vial away after 31 days.

Novolin N vials: Store at room temperature up to 25 degrees C (77 degrees F). Do not refrigerate. Do not freeze. Keep away from heat and light. Throw the opened vial away after 42 days.

Pens that you are using:

Humulin N KwikPens: Store at room temperature up to 30 degrees C (86 degrees F). Do not refrigerate or freeze. Keep away from heat and light. Throw the pen away after 14 days, even if it still has insulin left in it.

Novolin N FlexPens: Store at room temperature up to 30 degrees C (86 degrees F). Do not refrigerate or freeze. Keep away from heat and light. Throw the pen away after 28 days, even if it still has insulin left in it.

NOTE: This sheet is a summary. It may not cover all possible information. If you have questions about this medicine, talk to your doctor, pharmacist, or health care provider.

Copyright ©2023 Elsevier Inc. All Rights Reserved.

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Note: Introduction and Additional Common Questions written and medically approved by Cleveland Clinic professionals.

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