insulin NPH
Brand names: Humulin N, Novolin N
Humulin N is an intermediate-acting insulin that helps control blood sugar. It is used for adults and children with diabetes.
Drug Pricing (NADAC)
Brand Price
$9.05/unit
Generic Available
No
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Humulin N treats diabetes.
Common side effects
Low blood sugar (hypoglycemia), Allergic reactions like redness or itching at the injection site, Skin changes at the injection site
Key warnings
Never share your Humulin N KwikPen or syringes with anyone else, even if you change the needle.
How It Works
Humulin N is a man-made form of human insulin. It replaces the insulin your body should be making. This helps sugar get from your blood into your cells for energy.
How to Take It
Humulin N is injected under the skin. You can inject it into your belly, thigh, upper arm, or buttocks. Change your injection site each time to avoid skin problems. Your doctor will tell you how much insulin to use and when to take it.
Pregnancy & Breastfeeding
Tell your doctor if you are pregnant or plan to become pregnant. This medicine might pass into breast milk, but it is not expected to harm your baby. Talk to your doctor about the best way to manage your diabetes during pregnancy or while breastfeeding.
Missed Dose
If you miss a dose, check your blood sugar and follow your doctor's instructions. Do not take a double dose to make up for a missed dose.
Storage
Keep Humulin N in its original carton, away from heat and light, and do not freeze it.
Serious Warnings
Never share your Humulin N KwikPen or syringes with anyone else, even if you change the needle. Sharing pens or syringes can spread blood-borne illnesses. Changes in your insulin dose should be made carefully with your doctor's supervision. Low blood sugar can be very dangerous and even life-threatening.
Known Drug Interactions
7 DRUG INTERACTIONS Table 1: Clinically Significant Drug Interactions with HUMULIN N Drugs that May Increase the Risk of Hypoglycemia Drugs: Antidiabetic agents, ACE inhibitors, angiotensin II receptor blocking agents, disopyramide, fibrates, fluoxetine, monoamine oxidase inhibitors, pentoxifylline, pramlintide, salicylates, somatostatin analog (e.g., octreotide), and sulfonamide antibiotics Intervention: Dose adjustment and increased frequency of glucose monitoring may be required when HUMULIN N is co-administered with these drugs.
Mechanism: Fluoxetine can cause insulin to have a stronger effect on your blood sugar, making it more likely to drop below normal levels.
What to do: Check your blood sugar more often and ask your doctor if your insulin dose needs to be adjusted.
7 DRUG INTERACTIONS Table 1: Clinically Significant Drug Interactions with HUMULIN N Drugs that May Increase the Risk of Hypoglycemia Drugs: Antidiabetic agents, ACE inhibitors, angiotensin II receptor blocking agents, disopyramide, fibrates, fluoxetine, monoamine oxidase inhibitors, pentoxifylline, pramlintide, salicylates, somatostatin analog (e.g., octreotide), and sulfonamide antibiotics Intervention: Dose adjustment and increased frequency of glucose monitoring may be required when HUMULIN N is co-administered with these drugs.
Mechanism: Both medicines lower blood sugar, so using them at the same time increases the risk of your blood sugar dropping too low.
What to do: Your doctor may need to adjust your insulin dose and you should check your blood sugar levels more often.
7 DRUG INTERACTIONS Table 1: Clinically Significant Drug Interactions with HUMULIN N Drugs that May Increase the Risk of Hypoglycemia Drugs: Antidiabetic agents, ACE inhibitors, angiotensin II receptor blocking agents, disopyramide, fibrates, fluoxetine, monoamine oxidase inhibitors, pentoxifylline, pramlintide, salicylates, somatostatin analog (e.g., octreotide), and sulfonamide antibiotics Intervention: Dose adjustment and increased frequency of glucose monitoring may be required when HUMULIN N is co-administered with these drugs.
Mechanism: Octreotide can lower blood sugar, which adds to the effect of the insulin and makes a dangerous drop in blood sugar more likely.
What to do: You may need a dose adjustment and should monitor your blood sugar more frequently while taking both drugs.
Drugs that May Decrease the Blood Glucose Lowering Effect of HUMULIN N Drugs: Atypical antipsychotics (e.g., olanzapine and clozapine), corticosteroids, danazol, diuretics, estrogens, glucagon, isoniazid, niacin, oral contraceptives, phenothiazines, progestogens (e.g., in oral contraceptives), protease inhibitors, somatropin, sympathomimetic agents (e.g., albuterol, epinephrine, terbutaline), and thyroid hormones.
Mechanism: Albuterol is a stimulant-like drug that can raise blood sugar, making your insulin work less effectively.
What to do: Your doctor may need to adjust your insulin dose or have you check your blood sugar more often.
Drugs that May Increase or Decrease the Blood Glucose Lowering Effect of HUMULIN N Drugs: Alcohol, beta-blockers, clonidine, and lithium salts. Drugs that May Blunt Signs and Symptoms of Hypoglycemia Drugs: Beta-blockers, clonidine, guanethidine, and reserpine Intervention: Increased frequency of glucose monitoring may be required when HUMULIN N is co-administered with these drugs. ( 7 ) Antiadrenergic Drugs (e.g., beta-blockers, clonidine, guanethidine, and reserpine) : Signs and symptoms of hypoglycemia may be reduced or absent.
Mechanism: Clonidine can make your blood sugar levels unpredictable and hide the normal warning signs of low blood sugar, like a fast heartbeat.
What to do: You should check your blood sugar more often and be aware that you might not feel the usual symptoms of a low.
Common Questions
What should Humulin N look like?
Can I mix Humulin N with other insulins?
How often should I check my blood sugar?
What are the signs of low blood sugar?
What should I do if I have low blood sugar?
Can other medicines affect Humulin N?
What if I have kidney or liver problems?
Can I use Humulin N in an insulin pump?
How long can I store Humulin N at room temperature?
What if I see particles in my Humulin N?
What are the common side effects of insulin NPH?
Does insulin NPH interact with other medications?
What drug class is insulin NPH?
Is insulin NPH safe during pregnancy?
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Medication Guides
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Common Drug Interactions
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What the FDA Data Shows for insulin NPH
The FDA label for insulin NPH (sold under brand names such as Humulin N, Novolin N) classifies it as a prescription-only medication in the Intermediate-Acting Insulin class. Humulin N treats diabetes. Official labeling lists 5 commonly reported side effects, including Low blood sugar (hypoglycemia), Allergic reactions like redness or itching at the injection site, Skin changes at the injection site.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. Voluntary reports accumulate over the lifetime of a drug and reflect wide-ranging clinical use. The database also lists 11 documented drug interactions derived from FDA labeling, with the top-flagged interaction rated moderate severity. NADAC pricing from CMS.
Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: December 19, 2025
Read our methodology — how this data is sourced, computed, and verified.
All federal data sources used on this page
- FDA Orange Book — approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed — NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) — post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm — standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files — federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database — current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages