NPH Insulin: How to Use Cloudy Insulin Safely
NPH insulin (Humulin N, Novolin N) is cloudy and must be mixed before every dose. How to resuspend it, when it peaks, night-time lows and cost.
3 min read
Key takeaways
NPH is an intermediate-acting human insulin, used once or twice daily for background control. It is cloudy and must be gently mixed before every dose. Because it peaks several hours after injection, meal and snack timing matter more than with modern basal insulins.
NPH insulin at a glance
| Generic name | isophane human insulin |
|---|---|
| Made by | Eli Lilly; Novo Nordisk |
| Type | Intermediate-acting insulin |
| Form | Vials, pens |
| How often | Once or twice daily |
| United States | FDA-approved; available over the counter at many US pharmacies. |
| Canada | Available in Canada. |
Mix it every time
NPH crystals settle. Roll the vial or pen between your hands and tip it gently, as the instructions describe, until it is evenly cloudy — do not shake hard. An unmixed dose can be too weak or too strong.
Understanding the peak
NPH has a peak a few hours after injection. If you take it at night, that peak can fall in the early morning hours. Ask your clinician whether you need a bedtime snack or a different timing, and check your sugar overnight if you feel unwell on waking.
Using it with other insulin
NPH is sometimes mixed with regular insulin in the same syringe, drawing clear before cloudy. Only do this if your team has taught you; premixed 70/30 insulins do it for you.
Low blood sugar
Know your low-sugar plan. Signs include shaking, sweating, a fast heartbeat, hunger, confusion and irritability. A common approach is the rule of 15: take 15 g of fast-acting carbohydrate (glucose tablets, juice or regular soda), recheck after 15 minutes, and repeat if still low. Make sure someone close to you knows how to use rescue glucagon.
Cost
NPH is available over the counter at many US pharmacies and is one of the lowest-cost insulins.
Frequently asked questions
Why is my NPH cloudy but my other insulin clear?
NPH is a suspension; cloudiness is normal. Clear insulins should never look cloudy.
Can NPH replace Lantus?
Sometimes, for cost reasons, but the doses and timing differ. Switch only with your clinician's plan.
How many times should I roll the pen?
Follow your product's leaflet; most say to roll and tip it until it looks uniformly white and cloudy.
Keep reading
Sources
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General information based on the official label. It does not replace advice from your prescriber or pharmacist.