If you have type 2 diabetes, your doctor might suggest Januvia (sitagliptin) as a treatment option for you. Along with other questions you may have about the drug, you could be wondering about its side effects.

Januvia is a prescription drug. It’s used with diet and exercise to help manage blood sugar levels in adults with type 2 diabetes.

Januvia comes as a tablet that you take by mouth. It’s typically used as a long-term treatment. For more information about Januvia, see this in-depth article on the drug.

Like other drugs, Januvia can cause mild or serious side effects. Keep reading to learn more.

Some people may experience mild or serious side effects during their Januvia treatment. Examples of Januvia’s more commonly reported side effects include:

* To learn more about this side effect, see the “Side effects explained” section below.

Keep reading to learn about other possible mild and serious side effects of Januvia.

Some people may have mild side effects while taking Januvia.

Examples of mild side effects that have been reported with Januvia include:

* To learn more about this side effect, see the “Side effects explained” section below.

In most cases, these side effects should be temporary. And some may be easily managed, too. But if you have any symptoms that are ongoing or that bother you, talk with your doctor or pharmacist. And do not stop using Januvia unless your doctor recommends it.

Januvia may cause mild side effects other than the ones listed above. See the Januvia medication guide for details.

Note: After the Food and Drug Administration (FDA) approves a drug, it tracks and reviews side effects of the medication. If you’d like to notify the FDA about a side effect you’ve had with Januvia, visit MedWatch.

In rare cases, serious side effects can occur with Januvia.

Serious side effects that have been reported with Januvia include:

* To learn more about this side effect, see the “Side effects explained” section below.
† An allergic reaction is possible after using Januvia. But this side effect wasn’t reported in studies.

If you develop serious side effects while taking Januvia, call your doctor right away. If the side effects seem life threatening or if you think you’re having a medical emergency, immediately call 911 or your local emergency number.

Get answers to some frequently asked questions about Januvia’s side effects.

Can Januvia cause weight loss or weight gain?

Possibly. Weight loss and weight gain weren’t reported as side effects in studies of the drug.

Some people who took Januvia in these studies did have weight gain and weight loss. But it’s not clear if Januvia itself caused these weight changes.

Keep in mind that rapid weight gain can be a sign of heart failure, which is a possible serious side effect from Januvia. Tell your doctor right away if you notice a sudden increase in your weight.

If you’re concerned about weight changes while taking Januvia, talk with your doctor. They can suggest healthy ways to manage your weight.

Are there any reviews available from people who’ve used Januvia?

No, the drug’s manufacturer hasn’t provided reviews from people who’ve used Januvia.

If you have questions about what to expect with Januvia treatment, talk with your doctor or pharmacist.

Will my risk of side effects vary depending on which strength of Januvia I take (25 mg, 50 mg, or 100 mg)?

Maybe, but it isn’t known for sure. Studies of Januvia didn’t look at the side effects of the drug based on strength.

Your doctor may be able to tell you more about your risk of side effects from the strength of Januvia they prescribed.

Does Januvia cause yeast infections?

It’s not likely. Yeast infections weren’t reported as a side effect in studies of Januvia.

But diabetes, which Januvia is used to treat, can cause yeast infections. So it’s possible that you may have a yeast infection while taking Januvia. But the infection is likely a result of the condition you’re using Januvia to treat rather than the drug itself.

If you have questions about your risk of yeast infections while taking Januvia, talk with your doctor.

What are some of the long-term side effects of Januvia?

Januvia may cause certain long-term side effects.

For example, heart failure can occur with Januvia. And if heart failure worsens over time, this condition can lead to long-term problems. Examples of long-term effects from heart failure include abnormal heart rhythms, blood clots, and stroke.

If you’re concerned about long-term side effects from Januvia, talk with your doctor. They can suggest ways to lessen your risk of these side effects. They can also recommend ways to manage these side effects if you experience them.

Januvia 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 Januvia.

Conditions or factors that would prevent you from taking the medication are sometimes called contraindications.

The list below includes factors to consider before taking Januvia.

Heart failure. Januvia can cause new or worsening heart failure. Be sure to tell your doctor if you have heart failure before starting Januvia treatment. They may prescribe a drug other than Januvia for you.

Kidney problems. Tell your doctor if you have any kidney problems before starting Januvia. In rare cases, taking Januvia may cause severe kidney problems, such as acute (sudden) kidney failure. You may have a higher risk of this side effect if you already have kidney problems before taking Januvia. If you have kidney problems, your doctor may give you a lower dosage of the drug than usual.

Pancreatitis. In rare cases, Januvia may cause pancreatitis (swelling of the pancreas). If you have a history of this condition, tell your doctor before you start Januvia. It’s possible that you may have a higher risk of this side effect if you’ve had pancreatitis in the past. Your doctor will advise if it’s safe for you to use Januvia.

Allergic reaction. If you’ve had an allergic reaction to Januvia or any of its ingredients, you should not take Januvia. Ask your doctor what other medications are better options for you.

Alcohol use and Januvia

There aren’t known safety issues with drinking alcohol while taking Januvia.

However, alcohol can affect your blood sugar levels. If you have diabetes, this could make it difficult for you to manage your blood sugar.

Januvia is used to help manage blood sugar levels in people who have type 2 diabetes. Consuming alcohol during Januvia treatment could affect your blood sugar levels. So you may need to limit the amount of alcohol you drink while taking the drug.

If you drink alcohol, talk with your doctor about the amount that’s safe for you to drink while taking Januvia.

Pregnancy and breastfeeding while taking Januvia

It may not be safe to take Januvia while you’re pregnant or breastfeeding.

If you take Januvia during pregnancy, consider enrolling in Januvia’s pregnancy registry. This registry gathers important information about the effects of Januvia when it’s taken during pregnancy. This information can help researchers understand the risks and benefits of using the drug while pregnant.

To enroll in Januvia’s pregnancy registry, call 800-986-8999. You can also talk with your doctor about ways to enroll.

If you’re pregnant or breastfeeding, or planning to breastfeed or become pregnant while taking Januvia, talk with your doctor. They can tell you about the risks and benefits of taking the drug during these times.

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

Low blood sugar

Low blood sugar is a common side effect of Januvia.

You may have a higher risk of low blood sugar if you take Januvia in combination with certain diabetes drugs, including insulins and sulfonylureas. Glucotrol (glipizide) and Diabeta (glyburide) are examples of sulfonylureas.

Below are a few possible symptoms of low blood sugar:

What might help

If you experience symptoms of low blood sugar, try increasing your blood sugar levels by eating 15 grams of carbohydrates. Good sources for this purpose include glucose tablets, 4 ounces of juice or soda (but not diet soda), and hard candies. After 15 minutes, check your blood sugar, and take another 15 grams of carbohydrates if needed.

Also tell your doctor right away if you have symptoms of low blood sugar while taking Januvia. They may need to adjust the dosage of other diabetes drugs you may be taking.

Skin reactions

Skin reactions are a rare but possibly serious side effect of Januvia. Specifically, Januvia may cause bullous pemphigoid. This is a type of severe skin reaction that may need treatment in a hospital.

Bullous pemphigoid causes blistering on the skin, usually around the joints of the arms and legs. Blistering on the lower part of the belly may also occur.

What might help

If you have any skin reactions while taking Januvia, tell your doctor. They’ll likely have you stop taking the drug. They’ll also let you know if you need to go to a hospital to treat your condition. Or they may recommend that you see another healthcare professional, such as a dermatologist.

Headache

Headache is a common side effect of Januvia.

Keep in mind that headache can be a symptom of low blood sugar. This is another possible side effect of Januvia. For details, see “Low blood sugar” above.

What might help

Tell your doctor if you have headaches while taking Januvia. They may ask if you’re having any other symptoms of low blood sugar. They’ll make adjustments to your treatment plan if needed that will help raise your blood sugar. This may relieve your headache.

If your headaches aren’t related to low blood sugar, your doctor can suggest ways to manage this side effect. For example, they may recommend taking Tylenol (acetaminophen) or Advil (ibuprofen) to relieve your headaches.

But do not take any new medications with Januvia until you’ve talked with your doctor or pharmacist. Before you take new medications, they’ll make sure these drugs do not interact with Januvia or worsen any of Januvia’s side effects.

Allergic reaction

Like most drugs, Januvia can cause an allergic reaction in some people. This side effect wasn’t reported in studies. But allergic reaction to Januvia has been reported since the drug became available on the market.

Symptoms can be mild or serious and can include:

  • skin rash
  • itching
  • flushing (temporary warmth, redness, or deepening of skin color)
  • swelling under your skin, typically in your eyelids, lips, hands, or feet
  • swelling of your mouth, tongue, or throat, which can make it hard to breathe

What might help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. To manage your symptoms, they may suggest an over-the-counter antihistamine you take by mouth, such as Benadryl (diphenhydramine). Or they may recommend a product you apply to your skin, such as hydrocortisone cream.

If your doctor confirms you had a mild allergic reaction to Januvia, they’ll decide if you should continue using it.

If you have symptoms of a severe allergic reaction, such as swelling or trouble breathing, call 911 or your local emergency number right away. These symptoms could be life threatening and require immediate medical care.

If your doctor confirms you had a serious allergic reaction to Januvia, they may have you switch to a different treatment.

Keeping track of side effects

During your Januvia treatment, consider keeping notes on any side effects you’re having. Then, you can share this information with your doctor. This is especially helpful to do when you first start taking new drugs or using a combination of treatments.

Your side effect notes can include things such as:

  • what dose of drug you were taking when you had the side effect
  • how soon after starting that dose you had the side effect
  • what your symptoms were from the side effect
  • how it affected your daily activities
  • what other medications you were also taking
  • any other information you feel is important

Keeping notes and sharing them with your doctor will help your doctor learn more about how Januvia affects you. And your doctor can use this information to adjust your treatment plan if needed.

Januvia is used to treat type 2 diabetes. Some people may have mild side effects while taking the drug. In rare cases, others may experience serious side effects, such as heart failure.

If you have questions about Januvia’s side effects, talk with your doctor or pharmacist. See below for a few examples of questions you may want to ask:

  • Are muscle pain or hair loss a side effect of Januvia?
  • How can I manage my weight while taking Januvia?
  • What amount of alcohol is safe for me to drink while taking Januvia?
  • Do I have a higher risk of any of Januvia’s side effects?

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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.