Lantus (Insulin Glargine) - Subcutaneous

What Is Lantus?

Lantus (insulin glargine) is a long-acting prescription insulin used in adults and children with type 1 diabetes and adults with type 2 diabetes to improve blood sugar control.

Lantus is known as a basal insulin. As a long-acting insulin, basal insulin holds blood sugar steady (without food) throughout the day and night. People with type 1 diabetes (and some people with type 2 diabetes) also use short-acting insulin as bolus insulin at mealtimes and to correct blood sugar that is too high.

Lantus works by replacing the insulin that the body typically produces. It stops the liver from making more sugar and helps move sugar out of the blood to other body tissues, where it is used for energy.

Lantus is injected subcutaneously (under the skin) into the stomach, upper arm, or thigh. 

Lantus contains 100 units of insulin glargine per milliliter (mL). It is also available as a prefilled pen injection (called Lantus Solostar) and in vials.

Drug Facts

Generic Name: Insulin Glargine

Brand Name(s): Lantus, Lantus SoloStar, Basaglar, Semglee, Semglee Pen

Drug Availability: Prescription

Therapeutic Classification: Antidiabetic

Available Generically: No

Controlled Substance: N/A

Administration Route: Subcutaneous

Active Ingredient: Insulin Glargine

Dosage Form(s): Solution

What Is Lantus Used For?

The Food and Drug Administration (FDA) approved Lantus to improve blood sugar control in:

  • Adults and children (ages 6 years and older) with type 1 diabetes 
  • Adults with type 2 diabetes

Lantus is not used to treat diabetic ketoacidosis (DKA). DKA is a life-threatening complication of diabetes in which the body makes high levels of blood acids called ketones. DKA occurs more commonly in people with type 1 diabetes but can also occur in people with type 2 diabetes.

How to Take Lantus

When taking Lantus: 

  • Read the prescription label and the information leaflet that comes with your prescription.
  • Consult your healthcare provider if you have any questions. 
  • Use Lantus as directed by your provider. 
  • Do not use any more or any less Lantus than your provider tells you to, and do not skip doses.
Lantus (Insulin Glargine) Drug Information

Verywell / Dennis Madamba

Lantus is injected subcutaneously (under the skin) into the thigh, upper arm, or stomach. Never administer it in an insulin pump or mix it with other insulins.

A healthcare provider will show you where and how to administer this medication. Continuously rotate sites. If you use the injection pen, use a new needle for each injection. Discard the old needle in a sharps container, a hard plastic container used to safely get rid of needles.

When administering Lantus, avoid injecting into:

  • A vein or muscle
  • The same injection site two days in a row
  • Damaged, bruised, or scarred skin

Lantus is typically injected once daily at the same time every day. When treating type 1 diabetes (and in some cases when treating type 2 diabetes), you will also use short-acting insulin with meals and as directed by your provider.

Prepare your injection when you are ready to give it. Check the injection solution to make sure it is clear and colorless. Call your pharmacist if the solution looks cloudy, has changed colors, or has particles in it.

Talk to your healthcare provider about blood sugar monitoring, as well as hypoglycemia (low blood sugar), and how to treat it. Low blood sugar can cause hunger, dizziness, blurred vision, confusion, and shakiness. Your provider may instruct you on how to manage low blood sugar. You can also talk to your provider about a glucagon prescription, such as Baqsimi, which can treat low blood sugar in an emergency.


Store unopened Lantus in the refrigerator until ready to use or until its expiration date. You can also store unopened Lantus at room temperature (between 68 and 77 degrees Fahrenheit), but you must use it within 28 days.

Keep Lantus in its original container, away from heat and light. Do not store insulin near the cooling element in the refrigerator. Do not freeze insulin. If it is frozen, discard Lantus and call your pharmacist.

Once opened, the Lantus vial can be stored in either the refrigerator or at room temperature and must be used within 28 days. Store the injection pen at room temperature and use it within 28 days. Do not refrigerate the Lantus Solostar pen once you have opened it. If using the pen, remove the needle before storing the pen. Use a new needle for each injection. Never reuse a needle.

Keep Lantus out of the reach of children and pets.

Off-Label Uses

Sometimes, Lantus is used off-label, meaning it is used in ways that are not FDA approved.

Healthcare providers may prescribe Lantus for use in:

  • Children and adolescents who are overweight and are newly diagnosed with type 2 diabetes
  • Children and adolescents with type 2 diabetes not adequately controlled with diet, exercise, and oral medication
  • Children ages 2–5 years old with type 1 diabetes

How Long Does Lantus Take to Work?

Lantus starts lowering blood sugar in about 90 minutes. It has a constant action over 24 hours without a large peak effect. Each dose of Lantus lasts about 24 hours, so you will take it once a day to hold blood sugar at a steady level (without food).

What Are the Side Effects of Lantus?

This is not a complete list of side effects and others may occur. A medical professional can advise you on side effects. If you experience other effects, contact your pharmacist or a medical professional. You may report side effects to the FDA at or 800-FDA-1088.

Like other medications, Lantus may cause side effects. Let your healthcare provider know about any side effects you experience, especially if they worsen or do not go away.

Common Side Effects

The most common side effects of Lantus are:

  • Hypoglycemia (low blood sugar)
  • Injection site reaction
  • Injection site lipodystrophy (tissue swelling)
  • Muscle pain
  • Itching and rash
  • Upper respiratory infection or flu
  • Headache
  • Swelling of the extremities
  • Hypersensitivity reaction

Severe Side Effects

Call your healthcare provider right away if you have serious side effects. Call 911 if your symptoms feel life-threatening or if you think you’re having a medical emergency. Serious side effects and their symptoms can include:

  • Hypersensitivity reaction or anaphylaxis: Symptoms can include rash, hives, swelling around the lips, tongue, and face, and difficulty breathing, and require emergency medical attention. 
  • Hypoglycemia (low blood sugar): Talk to your healthcare provider about blood sugar monitoring and how to treat low blood sugar. Be aware of low blood sugar symptoms such as hunger, dizziness, shaking, sweating, confusion, blurred vision, and irritability. 
  • Hypokalemia (low potassium levels): Symptoms may include leg cramps, constipation, irregular heartbeat, fluttering in the chest, increased thirst/urination, numbness and tingling, muscle weakness, and limp feeling. Call your healthcare provider right away if any of these symptoms occur.

Long-Term Side Effects

While many people tolerate Lantus well, long-term or delayed side effects are possible. Some long-term side effects can be mild, such as:

  • Infection/flu
  • Muscle and joint pain
  • Weight gain 
  • Insulin resistance (when the body does not respond as well to insulin, and blood sugar increases as a result)

Moderate long-term side effects can include:

Severe long-term side effects may include:

  • Insulin shock: This is severely low blood sugar and is a medical emergency. Seek immediate assistance by calling 911.
  • Retinopathy: This condition causes eye complications that can lead to vision loss and blindness.

Report Side Effects

Lantus may cause other side effects. Call your healthcare provider if you have any unusual problems while taking this medication.

If you experience a serious side effect, you or your provider may send a report to the FDA's MedWatch Adverse Event Reporting Program or by phone (800-332-1088).

Dosage: How Much Insulin Glargine Should I Take?

Drug Content Provided and Reviewed by IBM Micromedex®

The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.

The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.

  • For injection dosage form (solution):
    • Basaglar® or Lantus®:
      • For type 1 diabetes mellitus:
        • Adults and children 6 years of age and older—Dose is based on your blood sugar and must be determined by your doctor.
        • Children younger than 6 years of age—Use and dose must be determined by your doctor.
      • For type 2 diabetes mellitus:
        • Adults—Dose is based on your blood sugar and must be determined by your doctor.
        • Children—Use and dose must be determined by your doctor.
    • Toujeo®:
      • For type 1 diabetes mellitus:
        • Adults and children 6 years of age and older—Dose is based on your blood sugar and must be determined by your doctor.
        • Children younger than 6 years of age and older—Use and dose must be determined by your doctor.
      • For type 2 diabetes mellitus:
        • Adults and children 6 years of age and older—Dose is based on your blood sugar and must be determined by your doctor.
        • Children younger than 6 years of age and older—Use and dose must be determined by your doctor.


In some cases, your healthcare provider will determine if you need to modify your treatment with Lantus.


Older adults (aged 65 years and older) may be prescribed Lantus if their healthcare provider determines that benefits outweigh risks. The prescribing information recommends conservative dosing to avoid low blood sugar. 

Lantus can be used in children aged 6 years and older with type 1 diabetes. However, it is not FDA-approved in children with type 2 diabetes.

People Who Are Pregnant or Breastfeeding 

People who are pregnant, planning to become pregnant, or breastfeeding should consult their healthcare provider for medical advice. If you are already using Lantus and find out that you are pregnant, notify your provider. 

Kidney or Liver Problems

People with kidney or liver problems may be prescribed Lantus with caution. In these cases, a healthcare provider may frequently monitor your treatment and adjust your dose, if necessary.

Missed Dose

Ask your healthcare provider what to do if you miss a dose. Do not use more than one dose in 24 hours unless your provider instructs you to do so. Always refill your prescription a few days early to account for any delays in processing the prescription. This will also help ensure that you do not miss a dose.

Overdose: What Happens If I Take Too Much Lantus?

Taking too much Lantus can cause low blood sugar and low potassium levels. More severe overdoses can cause low blood sugar with coma, seizure, or neurological impairment.

What Happens If I Overdose on Lantus?

If you think you or someone else may have overdosed on Lantus, call your healthcare provider or the Poison Control Center (800-222-1222). 

If someone collapses or isn’t breathing after taking Lantus, call 911.


Drug Content Provided and Reviewed by IBM Micromedex®

Never share insulin pens or cartridges with others under any circumstances. It is not safe for one pen to be used for more than one person. Sharing needles or pens can result in transmission of hepatitis viruses, HIV, or other bloodborne illnesses.

Your doctor will want to check your progress at regular visits, especially during the first few weeks you use this medicine. Blood tests may be needed to check for unwanted effects.

It is very important to follow carefully any instructions from your health care team about:

  • Alcohol—Drinking alcohol may cause severe low blood sugar. Discuss this with your health care team.
  • Other medicines—Do not take other medicines during the time you are using insulin glargine unless they have been discussed with your doctor. This especially includes nonprescription medicines such as aspirin, and medicines for appetite control, asthma, colds, cough, hay fever, or sinus problems.
  • Counseling—Other family members need to learn how to prevent side effects or help with side effects if they occur. Also, patients with diabetes may need special counseling about diabetes medicine dosing changes that might occur because of lifestyle changes, such as changes in exercise and diet. Furthermore, counseling on contraception and pregnancy is needed because of the problems that can occur in patients with diabetes during pregnancy.
  • Travel—Keep a recent prescription and your medical history with you. Be prepared for an emergency as you would normally. Make allowances for changing time zones and keep your meal times as close as possible to your usual meal times.

In case of emergency—There may be a time when you need emergency help for a problem caused by your diabetes. You need to be prepared for these emergencies. It is a good idea to:

  • Wear a medical identification (ID) bracelet or neck chain at all times. Also, carry an ID card in your wallet or purse that says that you have diabetes and a list of all of your medicines.
  • Keep an extra supply of insulin glargine and syringes with needles or injection devices on hand in case high blood sugar occurs.
  • Keep some kind of quick-acting sugar handy to treat low blood sugar.
  • Have a glucagon kit and a syringe and needle available in case severe low blood sugar occurs. Check and replace any expired kits regularly.

Too much insulin glargine can cause hypoglycemia (low blood sugar). Low blood sugar also can occur if you use insulin glargine with another antidiabetic medicine, changes in insulin regimen (eg, insulin strength, type of insulin, injection site), delay or miss a meal or snack, exercise more than usual, or drink alcohol. Symptoms of low blood sugar must be treated before they lead to unconsciousness (passing out). Different people may feel different symptoms of low blood sugar. It is important that you learn which symptoms of low blood sugar you usually have so that you can treat it quickly.

Symptoms of low blood sugar include anxiety, behavior change similar to being drunk, blurred vision, cold sweats, confusion, difficulty in thinking, dizziness or lightheadedness, drowsiness, excessive hunger, fast heartbeat, headache, irritability or abnormal behavior, nervousness, nightmares, restless sleep, shakiness, slurred speech, and tingling in the hands, feet, lips, or tongue.

If symptoms of low blood sugar occur, eat glucose tablets or gel, corn syrup, honey, or sugar cubes, or drink fruit juice, non diet soft drink, or sugar dissolved in water to relieve the symptoms. Also, check your blood for low blood sugar. Get to a doctor or a hospital right away if the symptoms do not improve. Someone should call for emergency help immediately if severe symptoms such as convulsions (seizures) or unconsciousness occur. Have a glucagon kit available, along with a syringe and needle, and know how to use it. Members of your household also should know how to use it.

Hyperglycemia (high blood sugar) may occur if you do not take enough or skip a dose of your antidiabetic medicine, changes in insulin regimen, overeat or do not follow your meal plan, have a fever or infection, or do not exercise as much as usual.

Symptoms of high blood sugar include blurred vision, drowsiness, dry mouth, flushed, dry skin, fruit-like breath odor, increased urination, ketones in the urine, loss of appetite, stomachache, nausea, or vomiting, tiredness, trouble breathing (rapid and deep), unconsciousness, and unusual thirst.

If symptoms of high blood sugar occur, check your blood sugar level and then call your doctor for instructions.

This medicine may make you dizzy or drowsy. Do not drive or do anything else that could be dangerous until you know how this medicine affects you.

This medicine may cause serious allergic reactions, including anaphylaxis, which can be life-threatening and requires immediate medical attention. Call your doctor right away if you have a rash, itching, trouble breathing, trouble swallowing, or any swelling of your hands, face, or mouth while you are using this medicine.

This medicine may cause low levels of potassium in your blood. Do not use medicines, supplements, or salt substitutes that contain potassium unless you have discussed this with your doctor.

Using this medicine together with other diabetes medicine (eg, pioglitazone, rosiglitazone, Actos®, Actoplus Met®, Avandia®) may cause serious heart problems or edema (fluid retention). Check with your doctor immediately if you are rapidly gaining weight, having chest pain or discomfort, extreme tiredness or weakness, trouble breathing, uneven heartbeat, or excessive swelling of the hands, wrist, ankles, or feet.

What Are Reasons I Shouldn’t Take Lantus?

Lantus is not appropriate for everyone. Some people should not take Lantus. You should not take this medication if you are allergic to insulin glargine or any of the inactive ingredients in Lantus. You also should not use Lantus if you have an episode of low blood sugar.

Lantus may be prescribed with caution in some people only if the healthcare provider determines it is safe.

Use Lantus with caution in people:

  • Who are experiencing infection, illness, or stress
  • With low potassium levels
  • With kidney or liver problems
  • With visual impairment (the Solostar pen form)
  • With localized cutaneous amyloidosis (skin with lumps)

What Other Medications May Interact With Lantus?

Tell your healthcare provider about all of the medicines you take, including prescription and over-the-counter medicines, and vitamins or supplements.

When taken with Lantus, certain drugs can increase the risk of low blood sugar and require a lower dose of Lantus and more frequent monitoring. Examples include:

  • Antidiabetic drugs
  • ACE inhibitors such as Zestril (lisinopril) and Altace (ramipril), among others
  • Angiotensin II receptor blockers such as Avapro (irbesartan) and Cozaar (losartan), among others
  • Disopyramide (available under the brand names Norpace and Norpace CR)
  • Fenofibrate (available under the brand names Antara, Fenoglide, and Lipofen, among others)
  • Monoamine oxidase inhibitors (MAOIs), a type of antidepressant 
  • Prozac (fluoxetine)

Some drugs can decrease the effect of Lantus and may require a higher dose of Lantus and more frequent monitoring. Examples include:

  • Atypical antipsychotics such as Zyprexa (olanzapine), among others
  • Corticosteroids such as prednisone (available under the brand names Deltasone and Rayos, among others)
  • Diuretics such as Lasix (furosemide) and Microzide (hydrochlorothiazide), among others
  • Thyroid hormones such as Synthroid (levothyroxine), among others

Some drugs or substances can either increase or decrease the effect of Lantus. Some examples include:

  • Alcohol
  • Beta-blockers such as Inderal (propranolol) and Zebeta (bisoprolol)
  • Clonidine (available under the brand names Catapres, Kapvay, and Nexiclon XR, among others)
  • Lithium (available under the brand names Eskalith, Eskalith CR, and Lithobid)

Finally, some drugs can mask symptoms of low blood sugar and require more frequent blood sugar monitoring. Examples include:

  • Beta-blockers
  • Clonidine 
  • Reserpine

Other drug interactions may occur with Lantus. Consult your healthcare provider for a complete list of drug interactions.

What Medications Are Similar?

Lantus contains the ingredient insulin glargine. Insulin glargine is also available as other brand-name insulins:

  • Basaglar: Contains insulin glargine and is available in the same dosage of Lantus, which is 100 units per mL. Basaglar is indicated for use in adults with type 1 or type 2 diabetes and in children at least 6 years old with type 1 diabetes.
  • Semglee: A biosimilar product to Lantus. Semglee contains 100 units per mL insulin glargine, the same dosage as Lantus. Semglee is the first interchangeable biosimilar insulin product approved by the FDA. This means that Semglee can be substituted for the brand-name (also known as the reference product) drug Lantus. Semglee is for use in adults with type 1 or type 2 diabetes and in children at least 6 years old with type 1 diabetes.
  • Toujeo: Also contains insulin glargine and is available in a higher dose than Lantus (300 units per mL). It is used for adults with type 1 or type 2 diabetes.
  • Soliqua: A drug containing both insulin glargine and lixisenatide (a GLP-1 agonist). It is used along with diet and exercise to improve blood sugar control in adults with type 2 diabetes.

Besides Lantus, other long-acting insulins include Levemir (insulin detemir) and Tresiba (insulin degludec).

Short-acting insulins are used in people with type 1 diabetes and sometimes used in people with type 2 diabetes. Examples include Humalog (insulin lispro) and Novolog (insulin aspart).

This list is a list of insulins also prescribed for diabetes. It is not a list of drugs recommended to take with Lantus. Ask your pharmacist or a healthcare practitioner if you have questions.

Frequently Asked Questions

  • What is Lantus used for?

    Lantus improves blood sugar control in adults and children with type 1 diabetes. It is also used in adults with type 2 diabetes. It is a long-acting basal (background) insulin and holds blood sugar steady between meals and overnight.

  • How does Lantus work?

    Lantus replaces insulin normally made by the body. Lantus also stops the liver from making more sugar and helps move sugar out of the blood to other tissues, where it is then used for energy.

  • What drugs should not be taken with Lantus?

    Various drugs may interact with Lantus by different mechanisms. See the section on drug interactions above for more details. Review your medication list with your healthcare provider before taking Lantus.

  • How long does it take for Lantus to work?

    A dose of Lantus starts to lower blood sugar in approximately 90 minutes. However, Lantus is a basal insulin that has a constant, even action over 24 hours without any large peaks. Since each dose lasts about 24 hours, you will usually take Lantus once daily.

  • What are the side effects of Lantus?

    The most common side effects of Lantus are low blood sugar, injection site reaction, muscle pain, itching, rash, upper respiratory infection, flu, headache, and edema (swelling). 

    Get emergency medical help right away if you have hives, difficulty breathing, or swelling around the face.

  • How do I stop taking Lantus?

    Your healthcare provider will advise you on how long to take Lantus. Do not stop taking the medication without guidance from your provider.

How Can I Stay Healthy While Taking Lantus?

Before you start to take Lantus, discuss your medical history and all of the medications you take with your healthcare provider.

When taking Lantus, follow your healthcare provider’s instructions for use. Read the patient information that comes with your prescription and consult your healthcare provider if you have any questions or concerns. Talk to your provider about blood sugar monitoring. Make sure you understand how and when to test your blood sugar.

Look out for the signs of low blood sugar, such as:

  • Hunger
  • Dizziness
  • Blurred vision
  • Confusion
  • Shakiness

Your provider will give you instructions on how to treat low blood sugar. For example, eating a certain amount of fast-acting carbohydrates such as glucose tablets or apple juice can help. Talk to your provider about a glucagon prescription, such as Baqsimi, which can help treat low blood sugar in an emergency.

Avoid drinking alcohol while taking Lantus. Check medications for alcohol content, such as cough syrups. Avoid driving until you know how Lantus affects you. Always check the prescription label before injecting Lantus.

Prepare a diabetes kit to take with you everywhere you go. You may want to include items such as:

  • A blood glucose testing meter and extra supplies, including strips, lancing device, lancets, alcohol wipes
  • Emergency contact information
  • Glucagon (either as an injection or nasal Baqsimi)
  • Low blood sugar treatments, such as glucose tablets and juice boxes

It is important to always wear a medical alert necklace or bracelet that can signal that you have diabetes to emergency responders.

Medical Disclaimer

Verywell Health's drug information is meant for educational purposes only and is not intended as a replacement for medical advice, diagnosis, or treatment from a healthcare professional. Consult your doctor before taking any new medication(s). IBM Watson Micromedex provides some of the drug content, as indicated on the page.

4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. U.S. National Library of Medicine. DailyMed. Label: Lantus - insulin glargine, injection solution.

  2. U.S. National Library of Medicine. MedlinePlus. Insulin glargine.

  3. Epocrates. Lantus.

  4. Prescribers’ Digital Reference. Insulin glargine - Drug Summary.

By Karen Berger, PharmD
Karen Berger, PharmD, is a community pharmacist and medical writer/reviewer.