If you have diabetes, your doctor may prescribe Lantus for you.

It’s a prescription drug that’s used to help manage blood sugar levels in:

Lantus isn’t used to treat diabetic ketoacidosis (DKA). (DKA is a serious complication of diabetes that causes acid to build up in the blood.)

To learn more about diabetes, see the “What is Lantus used for?” section below.

Lantus basics and classification

Lantus is classified as a long-acting insulin. It contains the active drug insulin glargine, which is a biologic drug. Biologic drugs are made from parts of living cells.

Lantus is available in a biosimilar form called insulin glargine-yfgn (Semglee). (Biosimilars are like generic drugs. But unlike generics, which are made for nonbiologic drugs, biosimilars are made for biologic drugs.)

Lantus comes as a liquid solution that’s given as an injection under your skin.

Lantus vials and SoloStar pens

Lantus solution comes in:

Read on to learn about Lantus’ dosage, side effects, uses, and more.

You may wonder how Lantus compares with other options, such as Basaglar.

Both Lantus and Basaglar contain insulin glargine.

To learn more about the similarities and differences between Lantus and Basaglar, see this detailed comparison.

Read on to find out about alternatives for Lantus. And check with your doctor about which drug is right for your needs.

Lantus vs. Levemir

Lantus contains insulin glargine, while Levemir contains insulin detemir. If you’d like to see a side-by-side description of these two drugs, read this article.

Lantus vs. Tresiba

Lantus contains insulin glargine, while Tresiba contains insulin degludec. Check out this article to learn more about Lantus versus Tresiba.

Lantus vs. Toujeo

Both Lantus and Toujeo contain insulin glargine. See this article to find out how the two medications compare.

Find answers below to some common questions about Lantus.

What is Lantus’ peak time, duration, and onset of action? Is it a fast-acting insulin?

Below are the duration and onset-of-action times for Lantus.

Lantus doesn’t have a peak time. (Peak time is the amount of time it takes for a drug to reach its maximum effect.) The effect of Lantus remains steady for up to 24 hours after it’s injected.

The duration of this drug’s effect in your body is about 24 hours. In other words, each dose of Lantus keeps working in your body for up to 24 hours after you inject it.

Lantus isn’t a fast-acting insulin. Fast-acting insulins start working in the body within 30 minutes of being injected.

Instead, Lantus is a long-acting insulin. Its onset time is 1.5 to 2 hours. This means the drug begins working in your body within 1.5 to 2 hours after you inject it.

If you have more questions about the peak, duration, and onset of Lantus, talk with your doctor or pharmacist.

Is there a dosing conversion for Tresiba and Lantus?

Yes, there is a dosing conversion for switching from Lantus to Tresiba, or vice versa.

If you’re interested in switching between these two drugs, talk with your doctor. If they approve a change from one drug to the other, they’ll tell you how to adjust your dosing. But do not change your treatment plan unless your doctor tells you it’s safe to do so.

Is Lantus similar to Humalog, Novolog, and Victoza?

Below are a few ways that Lantus, Humalog, Novolog, and Victoza are alike and different.

Lantus, Humalog, and Novolog are used to help control blood sugar levels in people who have type 1 or type 2 diabetes. Victoza is used to help control blood sugar levels only in people with type 2 diabetes.

Lantus is a long-acting insulin that contains the active drug insulin glargine. Humalog and Novolog are fast-acting insulins. Humalog contains the active drug insulin lispro, while Novolog contains the active drug insulin aspart.

Victoza isn’t a type of insulin. It belongs to a group of drugs called glucagon-like peptide-1 (GLP-1) receptor agonists. Victoza contains the active drug liraglutide.

To learn more about how Lantus, Humalog, Novolog, and Victoza compare, talk with your doctor or pharmacist.

How does Lantus work? What’s its half-life?

Lantus is used to help control blood sugar levels in certain people who have diabetes.

Diabetes is a condition that leads to high blood sugar. With diabetes, your body can’t effectively use the insulin that’s made in your pancreas. Or your pancreas just doesn’t make enough (or any) insulin. (Insulin is a hormone that helps lower your blood sugar levels.)

Lantus is a type of insulin. Its mechanism of action (how it works) is to add to or replace the insulin that’s naturally made by the human body.

Lantus helps lower your blood sugar level by:

  • helping your muscle cells and fat cells take up sugar from your blood
  • keeping your liver from making more blood sugar
  • stopping your body from breaking down fats and proteins so it can break down blood sugar instead

Lantus’ half-life is about 12 hours. (A drug’s half-life is the amount of time it takes for half of a drug’s dose to leave your body.) In other words, it takes about 12 hours for your body to get rid of half of a dose of Lantus.

If you have more questions about how Lantus works or its half-life, talk with your doctor or pharmacist.

How should I store Lantus? Does it need to be refrigerated?

The way you’ll store Lantus varies based on a few factors, including whether you’re using Lantus vials or pens. For details, see the list below.

  • Unopened Lantus vials. You’ll store these in the refrigerator at a temperature of 36°F to 46°F (2°C to 8°C). You can store them this way until the expiration date on the package. You can also store unopened Lantus vials at a room temperature below 86°F (30°C) for up to 28 days. But be sure to throw them away after 28 days.
  • Opened Lantus vials. You’ll store opened Lantus vials in the refrigerator or at room temperature for up to 28 days.
  • Unopened Lantus SoloStar pens. You’ll store unopened pens in the refrigerator. You can store them this way until the expiration date on the package. Or you can store unopened pens at room temperature for up to 28 days.
  • Opened Lantus SoloStar pens. You’ll store opened pens at room temperature for up to 28 days. You should not put them in the refrigerator.

Don’t ever freeze Lantus. Be sure to store vials and pens away from heat and light. And throw away any vials and pens that have been open for more than 28 days. Check out this article to learn about options for medication disposal. Also, talk with your pharmacist about safe ways to dispose of medications.

Does Lantus cause cancer?

It’s possible, but it isn’t known for sure.

Cancer wasn’t a side effect reported in initial studies of Lantus. Since then, there have been reports that long-term use of Lantus may be linked to an increased risk of breast cancer. But other studies have shown no connection between breast cancer and Lantus use.

Reports have also shown that diabetes, which Lantus is used to treat, may also raise your risk of certain cancers. These include stomach cancer and kidney cancer. So it’s possible that diabetes, instead of Lantus, could raise your risk of certain cancers.

If you’re concerned about your risk of cancer with Lantus, talk with your doctor.

Your doctor will recommend the dosage of Lantus that’s right for you. Below are commonly used dosages, but always take the dosage your doctor prescribes.

Forms and strengths

Lantus comes as a liquid solution that’s given as an injection under your skin.

Lantus is available in one strength of U-100. This means it contains 100 units of insulin per milliliter (mL) of solution.

Lantus vials and SoloStar pens

Lantus solution comes in:

Recommended dosages

Below is a dosage chart for the recommended starting dose of Lantus:

If you have:Your starting dose of Lantus will likely be:
type 1 diabetesabout one-third of your total daily insulin dose (the rest of which is made up of fast-acting insulin at mealtimes)
type 2 diabetesup to 10 units or 0.2 units of Lantus for every kilogram (kg)* of your body weight

* One kilogram is about 2.2 pounds.

You’ll need to monitor your blood sugar levels while using Lantus. Your doctor will show you how. And they may adjust your Lantus dosage based on this and other factors, such as:

  • the form of Lantus you use
  • your body weight
  • other medical conditions you may have
  • other medications you take, including other types of insulin

Your healthcare professional will teach you how to determine your Lantus dosage. They may suggest a dosing calculator for you to use.

Doctors typically prescribe Lantus to be used once a day, not twice a day. You can take it at any time of day, but it should be the same time every day. Most people follow a bedtime dosing schedule for Lantus. Be sure to follow your doctor’s instructions for when to take Lantus.

Questions about Lantus’ dosage

Below are answers to a few common questions related to Lantus’ dosage.

  • What if I miss a dose of Lantus? Take your missed dose of Lantus as soon as you remember. But if it’s almost time for your next dose, just skip the missed dose. Then take your next dose at its usual time. If you aren’t sure whether to take a missed dose or skip it, ask your doctor or pharmacist.
  • Will I need to use Lantus long term? Yes, possibly. You may need long-term treatment for your diabetes. If you and your doctor decide that Lantus is safe and effective for you, you may take it long term.
  • How long does Lantus take to work? Lantus starts working to manage your blood sugar levels within 1.5 to 2 hours after you take a dose.

Like most drugs, Lantus may cause mild or serious side effects. The lists below describe some of the more common side effects that Lantus may cause. These lists don’t include all possible side effects.

Keep in mind that side effects of a drug can depend on:

  • your age
  • other health conditions you have
  • other medications you take

Your doctor or pharmacist can tell you more about potential side effects of Lantus. They can also suggest ways to help reduce side effects.

Mild side effects

Here’s a short list of some of the mild side effects that Lantus can cause. To learn about other mild side effects, talk with your doctor or pharmacist. Or, you can read the patient information section in Lantus’ prescribing information.

Mild side effects of Lantus that have been reported include:

Mild side effects of many drugs may go away within a few days to a couple of weeks. But if they become bothersome, talk with your doctor or pharmacist.

* For more information about this side effect, see the “Side effect focus” section below.

Serious side effects

Serious side effects from Lantus can occur, but they aren’t common. If you have serious side effects from Lantus, call your doctor right away. But if you think you’re having a medical emergency, call 911 or your local emergency number.

Serious side effects of Lantus that have been reported include:

* For more information about this side effect, see the “Side effect focus” section below.

Side effect focus

Learn more about some of the side effects Lantus may cause.

Weight gain

You may have weight gain while using Lantus. This was one of the most common side effects in studies of the drug.

Keep in mind that weight gain can also be caused by edema (fluid buildup), which is another common side effect of Lantus. Fluid buildup from Lantus usually happens in your ankles, feet, or legs.

What might help

Be sure to tell your doctor if you have weight gain while using Lantus. If your weight changes while using this medication, they may adjust your Lantus dosage.

Your doctor can also suggest ways to maintain a healthy weight with diet and exercise while using Lantus.

Hypoglycemia

You may have hypoglycemia (low blood sugar level) while using Lantus. This is the most common side effect of all insulins, including Lantus.

Hypoglycemia occurs when your blood sugar falls below a certain healthy level. For most people with diabetes, blood sugar level is considered low when it falls below 70 milligrams per deciliter (mg/dL).

Hypoglycemia can lead to the following symptoms:

Severely low blood sugar can also cause seizures and loss of consciousness. If you have these conditions, you may not be able to respond to sound or touch.

What might help

To help prevent hypoglycemia with Lantus, your doctor will tell you how often to check your blood sugar level.

If you have symptoms of hypoglycemia, check your blood sugar level right away. If it’s below 70 mg/dL, the American Diabetes Association recommends that you follow the “15–15 rule.” To do this, you should eat at least 15 grams (g) of fast-acting carbohydrates. Wait 15 minutes, then check your blood sugar level again.

If your blood sugar level is still less than 70 mg/dL, eat another 15 g of fast-acting carbohydrates. Then, wait another 15 minutes to check your blood sugar. Repeat this cycle until your blood sugar level is at least 70 mg/dL.

Below are a few examples of sources that contain 15 g of fast-acting carbohydrates:

  • 4 ounces (oz) of fruit juice
  • 4 oz of regular (non-diet) soda
  • glucose gel, powder, tablets, or liquid; check the product’s label for how much equals 15 g
  • hard candy; read the candy’s label for how many pieces are equal to 15 g

In some cases, your blood sugar may be so low that someone else needs to help you treat it. Make sure a family member, friend, co-worker, or caregiver knows how to recognize and treat hypoglycemia.

Severe hypoglycemia is a medical emergency and should be treated right away. You or someone else should call 911 or your local emergency number if you have symptoms of this condition.

In case of emergency, your doctor may also prescribe glucagon along with your Lantus. (Glucagon helps prevent the effects of insulin during an episode of severe hypoglycemia.) Your doctor or pharmacist can tell you how to use glucagon for severe hypoglycemia.

Tell your doctor if you have hypoglycemia symptoms while using Lantus. They can help you understand what caused it. They can also suggest ways to help you avoid another hypoglycemia episode.

Reactions at your injection sites

You may have reactions at your Lantus injection sites. These side effects were common in studies of the drug.

Below are a few reactions that can happen around the area where Lantus is injected:

What might help

To lower your risk of reactions at your injection sites, it’s important to inject each dose of Lantus into a different area of your body. You can inject Lantus into your upper arms, upper thighs, or belly.

If you have any of the reactions listed above while using Lantus, avoid injecting the drug into that area until after the area has healed. And if you have persistent or bothersome injection site reactions while using Lantus, talk with your doctor.

Allergic reaction

Some people may have an allergic reaction to Lantus.

Symptoms of a mild allergic reaction can include:

  • skin rash
  • itchiness
  • flushing (temporary warmth, redness, or deepening of skin color)

A more severe allergic reaction is rare but possible. Symptoms of a severe allergic reaction can include swelling under your skin, typically in your eyelids, lips, hands, or feet. They can also include swelling of your tongue, mouth, or throat, which can cause trouble breathing.

Call your doctor right away if you have an allergic reaction to Lantus. But if you think you’re having a medical emergency, call 911 or your local emergency number.

Costs of prescription drugs can vary depending on many factors. These factors include what your insurance plan covers and which pharmacy you use. To find current prices for Lantus in your area, visit GoodRx.com.

Lantus contains the active drug insulin glargine, which is a biologic drug. Biologic drugs are made from parts of living cells.

Lantus is available in a biosimilar form called insulin glargine-yfgn (Semglee). Biosimilars are like generic drugs. But unlike generics, which are made for nonbiologic drugs, biosimilars are made for biologic drugs.

The cost of biosimilars may be different than brand-name drugs. Talk with your doctor if you’d like to know about taking Semglee.

If you have questions about how to pay for your prescription, talk with your doctor or pharmacist. You can also visit the Lantus manufacturer’s website to see if they have support options.

Your doctor will explain how you should take Lantus. They’ll also explain how much to take and how often. Be sure to follow your doctor’s instructions.

Taking Lantus

Lantus comes as a liquid solution that’s given as an injection under your skin.

Lantus solution comes in:

How to use Lantus SoloStar pens

Your doctor will show you how to give yourself injections using the Lantus SoloStar pen. You’ll need pen needles, which are dispensed or sold separately. You’ll attach a new needle to the pen before you inject each dose.

For detailed instructions, you can visit the drug manufacturer’s website. Or you can read the Lantus SoloStar instructions for use.

Note: It’s important that you do not share your Lantus Solostar pen with another person, even if you’ve changed the needle. Sharing injection pens and needles can increase your risk for getting or spreading infections.

How to use Lantus vials

Your doctor will show you how to give yourself injections from a Lantus vial using insulin syringes. Lantus doesn’t come with insulin syringes. You’ll need to get them separately from your pharmacy.

For detailed instructions, you can visit the drug manufacturer’s website.

Note: It’s important that you do not share your insulin syringes with another person. Sharing syringes can increase your risk for getting or spreading infections.

Lantus injection sites

You can inject Lantus into your:

  • upper arms
  • upper thighs
  • belly

To lower your risk of reactions at your injection sites, it’s important to inject each dose of Lantus into a different area of your body. (For details about possible injection site reactions, see “Side effect focus” in the “What are Lantus’ side effects?” section above.)

Questions about taking Lantus

Below is important information you should know about taking Lantus.

  • Should I take Lantus with food? You can take Lantus with or without food.
  • When should you not take Lantus? There are certain conditions under which you should not take Lantus. These include times you have a low blood sugar level, or if you’re allergic to Lantus. For details on when not to take this drug, see “Warnings” in the “What should be considered before taking Lantus?” section below.
Questions for your doctor

You may have questions about Lantus and your treatment plan. It’s important to discuss all your concerns with your doctor.

Here are a few tips that might help guide your discussion:

  • Before your appointment, write down questions such as:
    • How will Lantus affect my body, mood, or lifestyle?
  • Bring someone with you to your appointment if doing so will help you feel more comfortable.
  • If you don’t understand something related to your condition or treatment, ask your doctor to explain it to you.

Remember, your doctor and other healthcare professionals are available to help you. And they want you to get the best care possible. So, don’t be afraid to ask questions or offer feedback on your treatment.

Some important things to discuss with your doctor when considering Lantus include:

  • any medical conditions you have
  • your overall health
  • other medications you’re taking

These and other considerations are described below.

Interactions

Taking a medication with certain vaccines, foods, and other things can affect how the medication works. These effects are called interactions.

Before taking Lantus, be sure to tell your doctor about all medications you take, including prescription and over-the-counter types. Also describe any vitamins, herbs, or supplements you use. Your doctor or pharmacist can tell you about any interactions these items may cause with Lantus.

Interactions with drugs or supplements

Lantus can interact with several types of drugs. These drugs include:

This list does not contain all types of drugs that may interact with Lantus. Your doctor or pharmacist can tell you more about these interactions and any others that may occur with use of Lantus.

Warnings

Lantus may not be right for you if you have certain medical conditions or other factors that affect your health. Talk with your doctor about your health history before you take Lantus. Factors to consider include those in the list below.

  • Low blood sugar level. You should not take Lantus during an episode of low blood sugar level. This is because Lantus can cause and also worsen this condition. For details, see “Side effect focus” in the “What are Lantus’ side effects?” section above.
  • Low potassium level. Before taking Lantus, tell your doctor if you have low potassium level. Lantus may cause and also worsen your condition. Be sure to tell your doctor about all other medications you take. They can advise if these medications could raise your risk of this side effect.
  • Allergic reaction. If you’ve had an allergic reaction to Lantus or any of its ingredients, you should not take Lantus. Ask your doctor what other medications are better options for you.
  • Taking thiazolidinediones (TZDs). Before taking Lantus, tell your doctor if you’re taking diabetes medications called TZDs. Examples of TZDs include pioglitazone (Actos) and rosiglitazone (Avandia). When taken with TZDs, Lantus can raise your risk of swelling. And this could cause new or worsening heart failure. Your doctor can advise if it’s safe for you to take Lantus while using these medications.

Lantus and alcohol

It’s best to avoid drinking alcohol while using Lantus.

This is because alcohol can increase or decrease your blood sugar levels. And this can make it hard for Lantus to manage your blood sugar. For this reason, you may need to avoid drinking alcohol while taking Lantus.

If you drink alcohol, talk with your doctor about how much alcohol, if any, is safe for you to drink while using Lantus.

Pregnancy and breastfeeding

There aren’t any known safety issues with using Lantus while pregnant or breastfeeding. This drug is generally considered safe to use during these times.

If you’re pregnant, breastfeeding, or planning to be pregnant or breastfeed, talk with your doctor. They can describe the possible risks and benefits of using Lantus while pregnant. They can also tell you about any possible nursing implications of the drug.

If you have diabetes, your doctor may prescribe Lantus.

It’s a prescription drug that’s used to help control blood sugar levels. It’s prescribed for:

Diabetes is a condition that leads to high blood sugar. Your body’s cells use blood sugar as their primary source of energy. Your pancreas releases a hormone called insulin to help get sugar from your blood into your body’s cells.

With diabetes, your body can’t effectively use the insulin that’s made in your pancreas. Or your pancreas just doesn’t make enough (if any) insulin.

Over time, this can cause a high level of blood sugar to stay in your blood. And having high blood sugar that goes untreated for a long time can lead to serious problems. These include heart disease and kidney disease.

Lantus is a type of insulin. It adds to or replaces the insulin your body makes naturally.

It’s important to note that Lantus isn’t used to treat diabetic ketoacidosis (DKA). (DKA is a serious complication of diabetes that causes acid to build up in the blood.)

Do not take more Lantus than your doctor prescribes. Using more than this can lead to serious side effects.

Symptoms of overdose

Symptoms caused by an overdose can include:

What to do in case you take too much Lantus

Call your doctor if you think you’ve taken too much Lantus. You can also call 800-222-1222 to reach the American Association of Poison Control Centers or use its online resource. But if you have severe symptoms, immediately call 911 (or your local emergency number) or go to the nearest emergency room.

If you have diabetes, your doctor may prescribe Lantus for you. If you have questions about taking this drug, talk with your doctor or pharmacist.

Below are some questions you may want to consider asking:

  • Do any other medications I take interact with Lantus?
  • How often should I check my blood sugar level while I’m taking Lantus?

You may also want to ask your doctor about other treatment options for diabetes. Here are a couple of articles you may find helpful:

You can learn more about diabetes by signing up for Healthline’s type 2 diabetes newsletter.

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up to date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or another healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.