Humalog is a brand name for insulin lispro, a rapid-acting insulin analog used to control blood sugar levels in individuals with diabetes. It is designed to mimic the natural insulin produced by the pancreas, helping to regulate glucose levels after meals.

How Does Humalog Work?

Humalog works by facilitating the uptake of glucose into cells, where it can be used for energy or stored for future use. Unlike regular human insulin, which takes about 30 minutes to start working, Humalog begins to work within 15 minutes after injection. This rapid onset of action helps to control postprandial (after-meal) blood sugar spikes more effectively.

Humalog Mixes


Humalog Mix50/50 is a premixed insulin formulation containing 50% insulin lispro protamine suspension and 50% insulin lispro injection. This combination provides both rapid-acting and intermediate-acting insulin to help manage blood sugar levels throughout the day.


Humalog Mix75/25 is another premixed insulin formulation composed of 75% insulin lispro protamine suspension and 25% insulin lispro injection. This blend offers a different ratio of rapid-acting and intermediate-acting insulin, providing flexibility in diabetes management.

Humalog Products

Humalog Vial

Humalog is available in vial form, containing a sterile solution of insulin lispro for injection. The vial is designed for use with syringes and allows for precise dosage adjustment according to the individual’s insulin requirements. This option is suitable for patients who prefer traditional insulin administration methods.

Humalog Kwikpen

The Humalog Kwikpen is a disposable prefilled pen device that simplifies insulin administration. It contains a cartridge of insulin lispro and features a dial mechanism for selecting the desired dose. The Kwikpen offers convenience and ease of use, making it a popular choice among patients who prefer a more user-friendly insulin delivery method.

Humalog Junior Kwikpen

The Humalog Junior Kwikpen is specifically designed for pediatric patients and individuals who require smaller insulin doses. Similar to the standard Kwikpen, it comes prefilled with insulin lispro and offers a simplified dosing process. The Junior Kwikpen provides a convenient option for children and caregivers to manage diabetes effectively.

Humalog Cartridges

Humalog cartridges are used with reusable insulin pen devices, allowing for multiple injections with a single cartridge. These cartridges contain insulin lispro and are compatible with certain insulin pen models. Using cartridges offers a cost-effective and environmentally friendly option for insulin delivery, especially for patients who prefer the convenience of a pen device.

Precautions and Warnings With Humalog

  • Hypoglycemia: Humalog may cause low blood sugar levels (hypoglycemia), especially if the dosage is too high or if taken with other medications that lower blood sugar.
  • Hyperglycemia: Insulin therapy, including Humalog, can lead to hyperglycemia (high blood sugar) if the dosage is insufficient or if factors such as illness, stress, or changes in diet or physical activity occur.
  • Injection Site Reactions: Some patients may experience redness, swelling, or itching at the injection site.
  • Hypokalemia: Humalog may cause potassium levels in the blood to decrease (hypokalemia), particularly in patients with renal impairment or those taking medications that affect potassium levels.
  • Hypersensitivity Reactions: Rarely, individuals may experience allergic reactions to Humalog, including rash, itching, or difficulty breathing.
  • Pregnancy and Breastfeeding: Pregnant or breastfeeding women should consult with their healthcare provider before using Humalog, as insulin requirements may change during these periods.

Humalog Side Effects

While Humalog is generally well-tolerated, like any medication, it may cause side effects in some individuals. Side effects associated with Humalog may include:

Mild Side Effects

  • Injection site reactions, such as pain, redness, itchiness, or swelling around the area of your injection
  • Lipodystrophy (skin thickening or pitting around the injection site)
  • Rash
  • Itching
  • Swelling of your feet or ankles
  • Weight gain

Serious Side Effects

  • Hypokalemia (a low level of potassium in your blood). Symptoms can include:
    • Muscle weakness
    • Fatigue (lack of energy)
    • Muscle cramps or twitches
    • Constipation
    • Urinating more often than usual
    • Feeling thirsty
    • Irregular heartbeat
  • Allergic reaction
  • Hypoglycemia (low blood sugar)

Drug Interactions With Humalog

Humalog may interact with other medications, supplements, or substances, potentially affecting its effectiveness or increasing the risk of adverse effects. Some notable drug interactions with Humalog include: 

Strengths and Dosages of Humalog

Humalog Vial

  • Available in vial form containing insulin lispro solution for injection.
  • Strength: Typically available in 100 units/mL concentration.
  • Dosage: Patients can administer Humalog vial using insulin syringes, with dosages adjusted according to their insulin requirements and healthcare provider’s instructions.

Humalog Kwikpen

  • Available in prefilled pen devices containing insulin lispro solution.
  • Strength: Typically available in 100 units/mL concentration.
  • Dosage: Humalog Kwikpen allows for easy and convenient insulin administration, with doses selected using a dial mechanism. Patients can adjust their doses according to their prescribed insulin regimen and mealtime requirements.

Humalog Junior Kwikpen

  • Specifically designed for pediatric patients and individuals requiring smaller insulin doses.
  • Strength: Typically available in 100 units/mL concentration.
  • Dosage: The Humalog Junior Kwikpen provides a user-friendly option for children and caregivers to administer insulin accurately, with doses adjusted based on the patient’s insulin sensitivity and mealtime carbohydrate intake.

Humalog Cartridges

  • Used with reusable insulin pen devices for multiple injections.
  • Strength: Typically available in 100 units/mL concentration.
  • Dosage: Patients can load Humalog cartridges into compatible insulin pen devices, allowing for convenient and precise insulin dosing throughout the day. Doses can be adjusted as needed under the guidance of a healthcare professional.

Humalog Alternatives

While Humalog (insulin lispro) is a widely used rapid-acting insulin analog, there are several alternative medications available for managing blood sugar levels in individuals with diabetes. Some alternatives to Humalog include:

  • Novolog (insulin aspart): Novolog is another rapid-acting insulin analog that works similarly to Humalog. It has a rapid onset of action and is used to control postprandial blood sugar spikes.
  • Apidra (insulin glulisine): Apidra is a rapid-acting insulin analog with a quick onset of action, similar to Humalog and Novolog. It is used to manage blood sugar levels before or after meals in individuals with diabetes.
  • Regular Human Insulin (RHI): Regular human insulin is a short-acting insulin that has been available for many years. It takes longer to start working compared to rapid-acting insulin analogs like Humalog but may be a more affordable option for some patients.
  • Basal Insulins: In addition to rapid-acting insulin analogs, basal insulins such as Lantus (insulin glargine), Levemir (insulin detemir), and Tresiba (insulin degludec) are used to provide long-acting insulin coverage throughout the day, helping to control fasting blood sugar levels.
  • Insulin Pump Therapy: Insulin pump therapy, using devices such as the Omnipod or Medtronic MiniMed, delivers rapid-acting insulin continuously throughout the day, mimicking the basal insulin secretion of the pancreas. This method may offer more flexibility and precise insulin dosing compared to multiple daily injections.

Questions & Answers of Humalog

What is Humalog?

Humalog is a brand name for insulin lispro, a rapid-acting insulin analog used to control blood sugar levels in individuals with diabetes. It is designed to mimic the natural insulin produced by the pancreas, helping to regulate glucose levels after meals.

What type of insulin is Humalog?

Humalog is a rapid-acting insulin analog, which means it has a quick onset of action and is used to control postprandial (after-meal) blood sugar spikes.

How long does Humalog last?

The duration of action of Humalog varies depending on factors such as dosage, injection site, and individual insulin sensitivity. Generally, Humalog starts working within 15 minutes after injection and lasts for approximately 3 to 5 hours.

When does Humalog peak?

Humalog reaches its peak concentration in the blood approximately 30 to 90 minutes after injection. This peak time may vary among individuals and can be influenced by factors such as meal composition and physical activity.

What is the difference between Humalog and Novolog?

Below is a comparison table highlighting the differences between Humalog and Novolog:

Type of InsulinRapid-acting insulinRapid-acting insulin
Onset of Action15 minutes10-20 minutes
Peak Time30-90 minutes1-3 hours
Duration of Action3-5 hours3-5 hours
Mixing with Other InsulinsShould not be mixedShould not be mixed
Available FormsVial, Kwikpen, CartridgesVial, FlexPen, PumpCart

How to use Humalog Kwikpen?

To use Humalog Kwikpen, follow these steps:

  1. Wash your hands and the injection site.
  2. Insert a new disposable needle into the pen.
  3. Dial the dose according to your healthcare provider’s instructions.
  4. Inject the insulin subcutaneously (under the skin) as directed.
  5. Dispose of the needle properly and store the Kwikpen according to the manufacturer’s instructions.

How long can Humalog be out of the refrigerator?

Once opened, unopened vials, Kwikpens, and cartridges of Humalog can be kept at room temperature (below 86°F or 30°C) for up to 28 days. Avoid exposing insulin to excessive heat or direct sunlight.

How much does 1 unit of Humalog lower blood sugar?

The blood sugar-lowering effect of 1 unit of Humalog can vary among individuals and depends on factors such as insulin sensitivity and current blood sugar levels. It is important to work closely with your healthcare provider to determine the appropriate insulin dosage based on your individual insulin requirements and blood sugar targets.

IMPORTANT NOTE: The information provided here is for educational purposes only and is not intended to serve as medical advice, diagnosis, or treatment recommendations. It should not be taken as an endorsement of any specific medication or treatment. Individual health conditions and responses to treatment can vary greatly; therefore, this information should not be seen as a guarantee of safety, suitability, or effectiveness for any particular individual. Always consult with a healthcare professional for personalized medical advice and before making any decisions regarding your health or treatment plans.

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