There are many different medications available to help people with diabetes manage their blood sugar levels. Two of the prescription medications available are Humalog and NovoLog.

Humalog and NovoLog are two forms of fast-acting, injectable insulin. Doctors prescribe these drugs to help people with diabetes manage their blood glucose levels. The drugs work more quickly than other types of insulin.

People inject either Humalog or NovoLog under the fat in the skin. A person should check their blood sugar levels before taking either drug and eat shortly afterward. This will help prevent blood sugar levels from dropping too low and causing hypoglycemia.

Since both Humalog and NovoLog are fast-acting insulin, healthcare providers tend to prescribe a long-lasting insulin as well, in order to regulate a person’s blood sugar levels.

Although Humalog and NovoLog have similar onset of action, they are two different medications and are not always interchangeable. In this article, we cover the important differences between them.

Humalog vs. NovoLog

Insulin pens from humalog and novolog lined up.
Humalog and NovoLog are two forms of injectable insulin.

Humalog and NovoLog have several differences. Humalog is insulin lispro, whereas NovoLog is insulin aspart.

Humalog is primarily for use by adults and older children with type 1 diabetes. Doctors may also sometimes prescribe it to adults with type 2 diabetes. However, there is currently no research into how it affects children under the age of 3.

By contrast, doctors tend to prescribe NovoLog to people 2 years and older with type 1 or type 2 diabetes.

Both medications start to work within about 15 minutes, but NovoLog tends to be slightly faster.

In fact, NovoLog may start to work with around 5–10 minutes. Humalog will likely take a full 15 minutes to start working.

Another difference is in a person’s ability to alter the dose of the insulin. A person can dilute NovoLog to produce a lower dose, but it is not possible to dilute Humalog.

Forms and dosage

Both Humalog and NovoLog are available as injectable solutions. They both offer similar sized dosage options.

Humalog offers the following doses:

  • 3 milliliter (ml) prefilled KwikPen
  • 3 ml cartridges
  • 3 ml vials
  • 10 ml vials

NovoLog offers similar doses:

  • 3 ml FlexTouch
  • 3 ml FlexPen
  • 3 ml PenFill cartridges
  • 10 ml vials

Side effects of each

Humalog and NovoLog can both cause headaches and nausea.
Humalog and NovoLog can both cause headaches and nausea.

A common side effect of both Humalog and NovoLog is low blood sugar. Both medications help reduce a person’s blood sugar levels, so taking them when blood sugar levels are already low can cause an unsafe drop.

A person should always monitor their blood sugar levels and check them before injecting insulin.

Certain activities and lifestyle choices may also affect a person’s blood sugar levels. For this reason, they should adjust their medications accordingly. Physical activity levels, diet, and stress levels can all affect blood sugar levels.

Other possible side effects of Humalog and NovoLog can include:

In rarer cases, a person may experience additional side effects, such as:

Anyone experiencing the symptoms of an allergic reaction should seek emergency medical attention.


Humalog and NovoLog are brand name medications. They are only available as a prescription from a doctor or other healthcare provider. Generic medications are copies of brand name medications that use the same ingredients but tend to cost less.

A generic version of Humalog recently became available at about half the price of the brand name version. NovoLog is not yet available as a generic. However, insurance companies typically cover both drugs.

Both medications are widely available at most major pharmacies in the United States.

What to ask a doctor

A doctor can offer advice on starting or switching medication.
A doctor can offer advice on starting or switching medication.

Before switching to fast-acting insulin, a person should speak to their doctor about any other medications they are taking.

Both Humalog and NovoLog can interact with other medications and may accidentally cause blood sugar levels to drop too low.

People should tell their doctor if they are taking:

A person should also consider speaking to their doctor about their alcohol consumption. Alcohol can affect how either Humalog or NovoLog work in the body.

Taking over-the-counter medications and supplements can also affect insulin medications. A doctor will ask a person if they regularly use these.

Finally, a person should discuss their medical and family history with their doctor. People with kidney, heart, or liver disease may process insulin differently.


Typically, a doctor will prescribe either Humalog or NovoLog to a person whose blood sugar levels fluctuate dramatically throughout the day.

These two types of insulin medication can rapidly reduce high blood sugar. However, they are not entirely the same, and a person should be aware of the possible side effects of each before starting to take one.

It is always best to speak to a doctor about Humalog and NovoLog to determine which is the best option for managing diabetes.