Humulin R
Humulin R (insulin regular) is a short-acting insulin. It's used to control blood glucose (sugar) levels in adults and children with Type 1 diabetes (T1D) or Type 2 diabetes (T2D). Humulin R (insulin regular) is typically injected under the skin 2 to 3 times daily 30 minutes before meals. Some common side effects of Humulin R (insulin regular) include low blood sugar levels (hypoglycemia) and injection-site redness or pain. Humulin R (insulin regular) is available in two different strengths: U-100 (100 units/mL) and U-500 (500 units/mL). Both strengths come as vials, but the U-500 also comes as a prefilled pen.
Note: Humulin R U-500 is prescription only; Humulin R U-100 is available both OTC and by prescription.
What is Humulin R (insulin regular)?
What is Humulin R (insulin regular) used for?
How Humulin R (insulin regular) works
Humulin R (insulin regular) is an insulin. Insulin is a natural hormone your body makes to control blood sugar levels. It helps your body absorb and store sugar from the bloodstream after a meal. Insulin also stops your liver from making glucose (sugar). But people with diabetes can't make insulin, don't make enough insulin, or their body doesn't respond to insulin as it should.
Humulin R (insulin regular) is a short-acting, lab-made version of insulin. It helps your body manage blood sugar levels after meals. Humulin R (insulin regular) is used by people who don't make insulin or need more insulin than what their body can produce.
Drug Facts
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What are the side effects of Humulin R (insulin regular)?
Common Side Effects
- Low blood sugar
- Reactions where the medication is injected (e.g., redness, swelling, itching)
Other Side Effects
- Fat deposits under the skin or pitting of the skin where the medication is injected
- Weight gain
- Swelling (e.g., in the legs, ankles, or feet)
Serious Side Effects
- Severely low blood sugar: dizziness, shakiness, feeling confused, feeling irritable or anxious, feeling faint, sweating, extreme hunger, can't think clearly
- Dangerously low potassium levels: weakness, muscle cramps or twitches, constipation, abnormal heartbeat, tiredness, trouble breathing
- Severe allergic reaction: rash; hives; swelling of face, tongue, and throat; trouble breathing
Source: DailyMed
More on Humulin R (insulin regular) side effects
The following side effects have also been reported
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
Incidence not known
blurred vision
chills
cold sweats
confusion
convulsions
cool, pale skin
decreased urine
difficulty with swallowing
dizziness
fast heartbeat
flushing or redness of the skin
headache
increased hunger
increased thirst
irregular heartbeat
loss of appetite
muscle pain or cramps
nightmares
numbness or tingling in the hands, feet, or lips
puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
seizures
shakiness
slurred speech
sweating
swelling
tightness in the chest
unusual tiredness or weakness
unusually warm skin
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Incidence not known
Bleeding, blistering, burning, coldness, discoloration of the skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site
redistribution or accumulation of body fat
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
Pros and cons of Humulin R (insulin regular)
Pros
Can help manage both Type 1 and Type 2 diabetes
Available over the counter without a prescription (Humulin R U-100 only)
Comes as pen and vial (Humulin R U-500 only)
Pharmacist tips for Humulin R (insulin regular)
Don't use Humulin R (insulin regular) if you plan to skip a meal, unless your prescriber specifically told you to do so. Using Humulin R (insulin regular) without a meal raises your risk for hypoglycemia (dangerously low blood sugar).
Using Humulin R (insulin regular) can raise your risk of dangerously low blood sugar levels. It's important that you and your caregiver know how to recognize symptoms of low blood sugar level, such as sweating, shakiness, anxiety, and hunger.
When you're using Humulin R (insulin regular), make sure to always carry fast-acting sugars with you so that you can bring your blood sugar levels up when it drops too low.
Ask your prescriber about when you should check your blood sugar during the day as you take Humulin R (insulin regular). Keep a log of your blood sugar readings and show it to your prescriber at your office visits. This helps you and your prescriber keep track of how well Humulin R (insulin regular) is working for you and whether you need dose adjustments.
Tips on how to store Humulin R (insulin regular)
For U-100: Store unopened vials in the refrigerator until the expiration date written on the product. You can also keep them at room temperature for up to 31 days. Keep opened vials at room temperature or in the refrigerator for 31 days.
For U-500: Store unopened vials and pens in the refrigerator until the expiration date written on the product. You can also keep them at room temperature for up to 40 days (for the vials) or up to 28 days (for the pens). Keep opened vials at room temperature or in the refrigerator for up to 40 days after opening. Store opened pens only at room temperature (not in the refrigerator) for up to 28 days after opening.
Tips on how to use Humulin R (insulin regular)
Make sure you know how to prepare and administer Humulin R (insulin regular) to avoid accidentally hurting yourself or wasting the medication. Read the instructions for use for your specific Humulin R (insulin regular) product (e.g., U-100, U-500 KiwkPen, or U-500 vial), and ask your care team if you have any questions.
Before each time you use Humulin R (insulin regular), double check that you're using the correct insulin product and that your dose (number of units) that you've prepared is correct. This is important to prevent dosing mistakes that could lead to dangerously low blood sugar if you accidentally inject too much insulin.
Always use a new needle for each injection to help prevent infections and blocked needles. Don't reuse or share your injection supplies with other people to avoid spreading infections.
Humulin R (insulin regular) U-500 comes with it's own specific insulin syringe (U-500 syringe) that has unique markings on it. Only use this syringe to draw up Humulin R (insulin regular) U-500. Never use any other type of insulin syringe to draw up Humulin R (insulin regular) U-500, and never use the U-500 syringe to draw up other types of insulin.
How to prime the Humulin R (insulin regular) U-500 KwikPen: Prime the pen each time before you use it. Turn the dose selector to 5 units. Hold the pen with the needle pointing up and tap it so any air bubbles go to the top. With the needle still pointing up, press the push-button down until the dosing window shows "0"; you should see a small amount of insulin at the needle tip.
Where to inject Humulin R (insulin regular): Inject the medication under the skin in the stomach area, buttocks, upper legs (thighs), or upper arms. For each injection, pick a different place within the area that you choose. This helps prevent hard lumps from forming in the skin, pitted or thickened skin, and irritated skin.
After you inject Humulin R (insulin regular), throw the needle or syringe away in a sharps container or a heavy-duty plastic container (e.g., empty milk carton, laundry detergent bottle). This helps lower the risk of needle-stick injuries. Don't throw away needles or syringes in your trash can. Visit the FDA's website for guidance on how to throw away your sharps container when it's full in your specific state.
Frequently asked questions about Humulin R (insulin regular)
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What are the risks and warnings for Humulin R (insulin regular)?
Humulin R (insulin regular) can cause some serious health issues. This risk may be even higher for certain groups. If this worries you, talk to your doctor or pharmacist about other options.
Risk of infections from sharing injection supplies
Never share Humulin R (insulin regular) pens, any syringes, or any needles with anyone else. Sharing Humulin R (insulin regular) and other injection supplies with someone can raise the risk of spreading very dangerous infections to each other.
Risk of changes to blood sugar levels with changes to your insulin regimen
Risk factors: Changes in insulin strength | Changes in type of insulins you take | Change in insulin brand-name products | Changes in injection site
Changing your insulin or insulin routine, such as where you inject Humulin R (insulin regular) or switching to a different brand name of your insulins, can affect how your body responds to insulin. This can lead to either high or low blood sugar levels. In addition, injecting Humulin R (insulin regular) repeatedly into areas of skin that show signs of lipodystrophy, such as pitting or thickened skin, can result in high blood sugar levels.
Be sure to check your blood sugar levels more often if your diabetes care team instructs you to make certain changes to your insulin or insulin routine. This helps you see how the changes affect your blood sugar levels. Don't make changes to your Humulin R (insulin regular) dose or routine without first checking with your diabetes care team.
Dangerously low blood sugar levels (hypoglycemia)
Risk factors: Changes in diet and exercise | Drinking alcohol | Taking other medications for diabetes together with Humulin R (insulin regular) | Liver or kidney problems | Not using Humulin R (insulin regular) as directed
Using Humulin R (insulin regular) alone or together with other medications that lower blood sugar can lead to hypoglycemia, which is dangerously low blood sugar levels. If not treated in time, it can be life-threatening.
Check your blood sugar level regularly to make sure it's within a safe range. If your diabetes care team instructs you to mix different insulins together, read the label of the insulins carefully to make sure you're using the right products. But remember, Humulin R (insulin regular) should never be mixed with other insulins in the same syringe. If you make any changes to your diet or meal patterns, other medications, or how much you exercise, let your care team know because they might need to adjust your dose of Humulin R (insulin regular).
Make sure you're familiar with symptoms of hypoglycemia, such as feeling shaky, being nervous or anxious, sweating or body chills, and excessive hunger. Keep fast-acting sugars, such as glucose tablets, with you at all times so you can treat an episode of hypoglycemia. If your blood sugar levels don't improve even after you take fast-acting sugars, get medical help right away.
Low blood potassium levels
Risk factors: Taking other medications with Humulin R (insulin regular) that lower potassium
Humulin R (insulin regular) can cause low potassium levels in your blood, which can be dangerous. You're at higher risk if you're already taking medications that can lower potassium levels, such as loop diuretics. Because people with low blood potassium levels typically don't experience any symptoms, your care team might order blood tests to check your potassium levels regularly. And if needed, they'll prescribe you medications to bring your potassium level within a safe range. Get medical help right away if you notice symptoms of low potassium levels such as weakness, muscle cramps or twitches, and constipation.
Swelling and heart failure
Risk factors: Taking glitazones together with Humulin R (insulin regular) | Heart failure
Taking Humulin R (insulin regular) with glitazones (also known as thiazolidinediones), like Actos (pioglitazone), can cause your body to hold onto fluid. This can be especially dangerous if you have heart failure because additional fluid can worsen your condition and cause symptoms such as difficulty breathing, swelling, and tiredness.
Make sure to tell your diabetes care team if you have heart failure or if you're taking a glitazone before starting Humulin R (insulin regular).
Severe allergic reactions
Rarely, Humulin R (insulin regular) can cause a serious, life-threatening reaction (e.g., anaphylaxis). If you experience swelling in your lips, face, or tongue, rash, or trouble breathing, get medical help right away.
Humulin R (insulin regular) dosage forms
Typical dosing for Humulin R (insulin regular)
Your diabetes care team will determine your dose of Humulin R (insulin regular) based on different factors, such as your blood sugar level, your body weight, and how well your body responds to insulin.
Humulin R (insulin regular) is available in two different strengths:
U-100 (insulin regular 100 units/mL) - Prescription and OTC
U-500 (insulin regular 500 units/mL) - Prescription only; for people who need more than 200 units of insulin daily
Adults and children: The typical direction is to inject the prescribed dose of Humulin R (insulin regular) under the skin in the stomach, thigh, upper arm, or buttocks about 30 minutes before each meal.
Note: Humulin R (insulin regular) U-100 can be given as an injection into the vein (IV) by a healthcare professional (HCP), typically in a hospital setting.
Interactions between Humulin R (insulin regular) and other drugs
More on Humulin R (insulin regular) interactions
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Acebutolol
- Atenolol
- Betaxolol
- Bisoprolol
- Carteolol
- Carvedilol
- Celiprolol
- Esmolol
- Labetalol
- Levobunolol
- Metipranolol
- Metoprolol
- Nadolol
- Nebivolol
- Oxprenolol
- Penbutolol
- Pindolol
- Practolol
- Propranolol
- Sotalol
- Timolol
How much does Humulin R (insulin regular) cost?
Humulin R (insulin regular) contraindications
Use during episodes of low blood sugar (hypoglycemia)
What are alternatives to Humulin R (insulin regular)?
Type 1 diabetes in adults and children
Type 2 diabetes in adults
What is the latest news about Humulin R (insulin regular)?
Humulin R (insulin regular) images
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References
Best studies we foundCenters for Disease Control and Prevention. (2024). Types of insulin.
Chelliah, A., et al. (2004). Insulin edema in the twenty-first century: Review of the existing literature. Journal of Investigative Medicine.
Clinical Diabetes. (2012). Hypoglycemia? Low blood glucose? Low blood sugar?
Eli Lilly and Company. (2022). Instructions for use: Humulin® (HU-mu-lin) R (insulin human) injection, for subcutaneous or intravenous use 3 mL or 10 mL multiple-dose vial (100 units/mL).
Eli Lilly and Company. (2022). Instructions for use: Humulin® R U-400 KwikPen® (insulin human) injection, for subcutaneous use 3 mL single-patient-use pen (500 units/mL, U-500).
Eli Lilly and Company. (2022). Instructions for use: Humulin® R U-500 (insulin human) injection, for subcutaneous use 20 mL multiple-dose vial (500 units/mL).
Eli Lilly and Company. (2023). Humulin R- insulin human injection, solution; Humulin R- insulin human injection, solution [package insert]. DailyMed.
Eli Lilly and Company. (2024). Humulin R U-500- insulin human injection, solution; Humulin R U-500 Kwikpen- insulin human injection, solution [package insert]. DailyMed.
Endocrine Society. (n.d.). Mealtime insulin: What you need to know.
Kadiyala, P., et al. (2014). Insulin induced lipodystrophy. The British Journal of Diabetes.
Munguia, C., et al. (2023). Regular insulin. StatPearls.
Russell-Jones, D., et al. (2007). Insulin-associated weight gain in diabetes--causes, effects and coping strategies. Diabetes, Obesity & Metabolism.
Sharabi, K., et al. (2015). Molecular pathophysiology of hepatic glucose production. Molecular Aspects of Medicine.
U.S. Food and Drug Administration. (2016). FDA approves a dedicated syringe to be used with Humulin R U-500 insulin.
U.S. Food and Drug Administration. (2021). Safely using sharps (needles and syringes) at home, at work, and on travel.
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