Humalog vs. Novolog: Compare Similarities, Differences, and How to Save

Insulin is a natural hormone in the body. But it also comes as a medication to treat diabetes. When used as a medication, it’s injected and takes the place of what’s normally made by your pancreas. If you have Type 1 or Type 2 diabetes, you may already be taking insulin to help keep your blood glucose (sugar) levels stable and healthy. 

There are many different types of injectable insulins. Humalog (insulin lispro) and Novolog (insulin aspart) are both rapid-acting insulins. They’re injected at mealtimes and to correct high glucose levels. They can also be used in an insulin pump.

Rapid-acting insulins start working within about 15 minutes after they’re injected. But is one better than the other? Let’s look at the similarities and differences between Humalog versus Novolog.

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Similarities between Humalog and Novolog

Although there aren’t many studies directly comparing Humalog versus Novolog, some small studies suggest they’re equally effective. Here are a few other similarities they share:

1. How they’re given

Both Humalog and Novolog are injected subcutaneously (under your skin). They can be given in the following areas:

• Stomach

• Buttocks

• Thighs

• Upper arms

Changing your injection site and rotating insulin pump sites can help to prevent:

• Lipodystrophy: This is a change in the way fat is distributed in the areas where insulin is injected. Areas with reduced fat can look like pits (indentations), while areas with more fat can appear as thickened on the skin. 

• Amyloidosis: This causes protein buildup in the skin that can make it look lumpy.

2. Formulations

Humalog and Novolog come in multiple forms. They’re both available as 3 mL prefilled pens, 3 mL cartridges, and 10 mL vials. Humalog also comes in 3 ml vials. Vials tend to be cheaper than pens, but pens and cartridges can be easier to use.

3. How they’re stored

Novolog and Humalog have similar storage instructions. They’re both sensitive to light and temperature changes (hot and cold). Regardless of the insulin you’re using, don’t store it in the freezer or near the cooling element in the refrigerator (the part that keeps the fridge cold). If your insulin freezes, don’t use it. 

If you’re using Humalog or Novolog in an insulin pump, it’s important to protect the insulin inside the pump from the elements, too.

Insulin vials

It’s best to store unopened insulin vials in the refrigerator where they’ll last until their expiration date. You can also leave them at room temperature, but they won’t last as long (28 days only). Once opened, Humalog and Novolog vials last in the fridge or at room temperature for up to 28 days. 

Insulin pens 

Store unopened insulin pens in the refrigerator until their expiration date. Once they’re opened, don’t put them back in the fridge. Opened Humalog and Novolog pens can be stored at room temperature for up to 28 days. 

Keep in mind: Insulin at refrigerated temperature should be between 36°F to 46°F. If you’re keeping insulin at room temperature, it should be between 59°F to 77°F or up to 86°F, depending on the product you’re using. 

4. How quickly they work 

Novolog and Humalog both start working within 15 minutes, peak in about 1 hour, and last for about 2 to 4 hours after injection.

5. Drug interactions with other diabetes medications

Humalog and Novolog can have drug interactions. This includes interactions with other diabetes medications. Using insulin with certain other diabetes medications can make it more likely you’ll experience low blood glucose (hypoglycemia). Examples include:

• Glucagon-like peptide-1 (GLP-1) agonists like Victoza (liraglutide)

• Glitazones like Actos (pioglitazone)

• Amylin analogues like Symlin (pramlintide) 

• Sulfonylureas like glipizide (Glucotrol XL)

These aren’t all the medications that can interact with Humalog and Novolog. For example, some medications can make Humalog or Novolog less effective. This includes atypical antipsychotic and corticosteroids. Always talk with your healthcare provider or pharmacist before starting a new medication. They can help you check for drug interactions.

6. Side effects

Humalog and Novolog share common side effects. With both medications, you may experience:

• Hypoglycemia

• Headache

• Injection site reactions

• Weight gain 

• Various infections

Humalog may also cause flu-like symptoms, pain, and cough. Novolog may also make your muscles slow to react, impair your senses, and cause nausea.

While uncommon, Humalog and Novolog can cause more serious side effects. These include:

• Severe hypoglycemia. Signs of hypoglycemia include shakiness, dizziness, and sweating. You may also experience hunger, a fast heartbeat, and other side effects. If you notice symptoms of hypoglycemia, you'll want to treat it immediately. You can do this with a fast-acting sugar source, like half a cup of fruit juice or 4 glucose tablets. If your symptoms are severe, you may need emergency care.

• Severe allergic reactions. Dangerous allergic reactions (anaphylaxis) rarely occur with Humalog and Novolog, but they’re possible. These reactions may involve throat tightness, hives, and swelling. You may develop trouble breathing in the most severe cases. If you develop anaphylaxis, seek emergency care immediately.

• Low potassium levels (hypokalemia). Symptoms of hypokalemia include muscle weakness and twitching, fatigue, and numbness. In more serious cases, it can cause vomiting, confusion, and an irregular heartbeat. Seek immediate medical attention if you think that you’re experiencing severe hypokalemia symptoms.

7. Who should avoid Humalog and Novolog

If you’re actively experiencing hypoglycemia, don’t take Humalog or Novolog until your blood glucose is stable. Using these insulin products can lower your blood glucose further, possibly creating an emergency situation.

If you’re allergic to any of the ingredients used in Humalog or Novolog, avoid using these insulin products. 

Differences between Humalog and Novolog

Humalog and Novolog have a lot in common, but they also have some key differences. 

1. Use in children with Type 1 diabetes

Humalog is FDA approved for use in children with Type 1 diabetes who are at least 3 years old. Novolog, however, is FDA approved for use in children with Type 1 diabetes who are at least 2 years old. 

2. When to inject them 

Humalog and Novolog both work quickly. The product label for Humalog recommends injecting it before eating a meal (within 15 minutes). You can also inject it right after eating. The product label for Novolog recommends injecting it within 5 to 10 minutes before a meal. 

But these recommendations don’t apply to everyone. Your diabetes care team will give you specific instructions for injecting Humalog or Novolog. This can vary person to person.

How to save on Humalog and Novolog

Humalog and Novolog are available as brand-name medications. But you can also find them as lower-cost generics. GoodRx can help you navigate the many ways to save on your prescription.

• GoodRx can help you save over 70% off the average retail price of generic Humalog. For example, one generic Humalog 10 mL vial may be less than $44 and five prefilled pens may cost under $80 at certain pharmacies with a GoodRx discount.

• It’s possible to save 65% off the average retail price of generic Novolog. One generic Novolog 10 mL vial is less than $58 and five prefilled pens may cost about $110 at certain pharmacies with a free GoodRx discount. 

• You can save with patient assistance programs. If you’re uninsured or underinsured, you may be eligible for Humalog and Novolog patient assistance programs, which offer the medication at no charge.

• Another way to save is with a copay savings card. If you have commercial insurance and meet eligibility requirements, brand-name Novolog is as little as $25 a month if you use the manufacturer’s savings card. And if you have commercial insurance or no insurance, brand-name Humalog may be as little as $35 if you use the manufacturer’s savings card.

Are Humalog and Novolog interchangeable?

No. If you’re prescribed Humalog, you can’t switch it out for Novolog. And if you’re prescribed Novolog, you shouldn’t use Humalog in its place. 

If your insurance coverage changes, and the insulin you take is no longer covered, talk to your healthcare team about what to do next.

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Written by:

Makaela Premont, PharmD

Makaela Premont, PharmD, is a pharmacist and the founder of uniquelymickie.com, a website dedicated to helping pharmacy students and pharmacists create a life that they enjoy. She received her Doctorate of Pharmacy from the University of South Carolina and is a licensed pharmacist in North Carolina.

Edited by:

Amy B. Gragnolati, PharmD, BCPS

Amy Gragnolati, PharmD, BCPS, is a pharmacy editor for GoodRx. Amy currently holds her pharmacist license in Georgia and California.

Reviewed by:

Jewels Doskicz, RN, BA

Jewels Doskicz, RN, BA, is an Arizona-based registered nurse with 22 years of hospital-wide clinical nursing experience and 11 years of medical writing and editing experience. She was a former healthcare content creator for a digital health tool at HealthLoop and director of clinical content operations at GetWellNetwork.

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