Januvia dosage, forms, and strengths

Januvia is a brand-name prescription drug that helps reduce blood sugar in people with Type 2 diabetes mellitus. The active ingredient in Januvia is sitagliptin phosphate, a type of drug belonging to a family of diabetes drugs called dipeptidyl peptidase 4 inhibitors or, for short, DPP-4 inhibitors or just plain “gliptins.” Sitagliptin increases the amount of insulin in the body when blood sugar levels rise in the body after a meal. It does this by blocking the body’s normal breakdown of insulin, the hormone that signals cells in the body to absorb sugar from the blood. Sitagliptin also blocks the production of glucagon, a hormone that increases the liver’s production of glucose. Combined, these two effects help to reduce blood sugar after eating.

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Januvia forms and strengths

Januvia is taken as a tablet in one of three dose strengths. Although the standard daily dose is 100 mg, the lower dose tablets are taken by people with kidney problems.

• Tablets: 25 milligrams (mg), 50 mg, 100 mg

Januvia dosage for adults

Taken as a tablet once per day, Januvia helps to control blood glucose levels in adults with Type 2 diabetes mellitus. Januvia is not an appropriate medication for Type 1 diabetes. 

Some patients may be prescribed Januvia as a single drug treatment (or monotherapy). Most people, however, will take Januvia with one or two other diabetes drugs including metformin, pioglitazone, rosiglitazone, glimepiride, or insulin. In addition to Januvia, sitagliptin is an active ingredient in at least two combination diabetes drugs manufactured by Merck Sharp & Dohme: Janumet (sitagliptin and metformin) and Steglujan (sitagliptin and ertugliflozin). 

Source: Epocrates, PDR

Januvia dosage for Type 2 diabetes

Sitagliptin, the active ingredient in Januvia, increases the body’s removal of glucose from the bloodstream and decreases the body’s production of glucose. Its basic mechanism of action is to block an enzyme called DPP-4. This enzyme breaks down incretins, the hormones that signal the body to make insulin, which in turn signals cells to absorb glucose from the blood. Incretin levels go up after a meal and are broken down by DPP-4 so that blood sugar levels don’t go down too far. By blocking DPP-4, sitagliptin allows incretin hormones and insulin to last longer in the body so that the body’s cells remove more glucose from the blood. Because the body starts producing incretin hormones when blood sugar goes up and stops producing incretin when blood sugar goes down, sitagliptin only works at reducing blood glucose when glucose levels are high. As a result, DPP-4 inhibitors like sitagliptin are less likely than other diabetes medications to cause hypoglycemia, or low blood sugar.

Used together with diet and exercise, Januvia reduced hemoglobin A1C an average of 0.7% when combined with metformin in clinical trials—the same as combining metformin with glipizide, a common dual therapy for Type 2 diabetes, but with a lower risk of hypoglycemia. Clinical studies have also shown that Januvia improves fasting glucose and significantly improves postprandial (“after a meal”) glucose in people with Type 2 diabetes.

• Standard dosage for Type 2 diabetes in adults: 100 mg taken once daily

• Maximum dosage for Type 2 diabetes in adults: 100 mg per day

Januvia dosage for children

The U.S. Food and Drug Administration (FDA) has not approved Januvia for use in children. Its safety and effectiveness in children have not been established. 

Januvia dosage restrictions

Januvia can be risky in some people with pre-existing health problems or conditions. A few people may not be able to safely take Januvia. These include people with Type 1 diabetes or diabetic ketoacidosis (elevated ketones in the blood) or anyone who has had an allergic reaction to Januvia. Some people with certain health conditions should take Januvia with caution, such as people at risk of heart failure, who have kidney problems, or who have a history of pancreatitis (inflamed pancreas). Finally, people taking other diabetes medications, particularly sulfonylureas and meglitinides, may require dosage adjustments of those medications to reduce the risk of low blood sugar (hypoglycemia).

People with kidney problems will be given a lower dose of Januvia. Januvia is eliminated from the body through the kidneys, so if the kidneys are not working well, higher concentrations of the drug could build up in the body and increase side effects. Healthcare providers measure renal function by the kidney’s filtration rate, or eGFR. The lower the eGFR, the less capable the kidneys are in filtering waste from the blood. End-stage renal disease requires mechanical blood filtration through dialysis, but even people on dialysis can take Januvia at the lowest recommended dose.

Renally impaired patients (kidney disease): 

• Moderate renal impairment—eGFR = 30-44: 50 mg per day

• Moderate to severe renal impairment— eGFR <30: 25 mg per day

• Dialysis: 25 mg per day, no supplement

How to take Januvia

Each dose of Januvia is taken only once per day with or without food. 

• Follow all the directions given by a healthcare provider. The dose usually doesn’t change unless there are problems. If it does change, make sure you understand the correct daily dose.

• Januvia should come with a medication guide. Please read the guide carefully before starting this medication and each time it’s refilled. If the medication guide is missing, ask a pharmacist for a copy.

• Januvia may be prescribed along with other diabetes medications. Take all other diabetes medications as directed.

• Take only one Januvia dose each day.

• Follow all the doctor’s recommendations on diet and exercise while taking Januvia.

• Store Januvia at room temperature (68°F to 77°F) and out of the reach of children in a closed container or pill organizer.

Januvia dosage FAQs

How long does Januvia stay in your system?

The terminal half-life of sitagliptin is about 12.5 hours, meaning half a dose of Januvia is cleared from the body in that time. That means it will take about two days for the body to completely eliminate a dose of Januvia. 

What happens if I miss a dose of Januvia?

Januvia is taken only once per day, so take a missed dose as soon as it’s remembered. If it’s getting near time for the next daily dose, however, skip the missed dose and take the next dose at its regularly scheduled time. Never take two doses to make up for a missed dose.

How long can you take Januvia?

Januvia is intended for the long-term treatment of Type 2 diabetes. However, diabetes is a progressive disorder, so Januvia may partly lose its effectiveness in controlling blood sugar.

How do I stop taking Januvia?

People can stop taking Januvia at any time without experiencing withdrawal symptoms. However, blood sugar levels are still a problem, so if the person is not being medicated for diabetes, glucose levels may rise to unsafe levels when Januvia is stopped. As a general rule, don’t stop taking any diabetes medication until talking to a healthcare professional first. 

People stop taking Januvia for many reasons. In some cases, it doesn’t help reduce blood sugar. In other cases, serious side effects of Januvia may require that it be immediately discontinued, especially allergic reactions (such as angioedema), heart failure, severe muscle pain, kidney failure, severe skin reactions, or inflamed pancreas (pancreatitis). Common side effects of Januvia, such as headaches, joint pain, upper respiratory tract infections, diarrhea, and constipation, might be too hard to live with. Some people may experience weight gain while on Januvia and stop the medicine for that reason, but weight gain is not considered a side effect of sitagliptin.

Januvia, fortunately, is only one among many effective medications that help control blood sugar. In place of Januvia, a healthcare provider could prescribe another DPP-4 inhibitor or turn to other types of diabetic medications including biguanides, sulfonylureas, meglitinides, glitazones, alpha-glucosidase inhibitors, incretin mimetics, dopamine-2 agonists, bile acid sequestrants, thiazolidinediones, and insulin. These can be prescribed as monotherapy or in combination to bring blood sugar under control.

What is the maximum dosage for Januvia?

100 mg of Januvia per day is both the standard and the maximum dose. People with renal insufficiency, though, may be given a lower daily dose.

Can you overdose on Januvia?

If too much Januvia is taken, call a poison helpline or get immediate medical help. An overdose may cause low blood sugar. Symptoms of low blood sugar include weakness, confusion, sweating, drowsiness, dizziness, fast heartbeat, and confusion. If multiple diabetes medications are being taken or a person is at risk of low blood sugar a healthcare professional may prescribe a glucagon injection kit to use in cases of severe hypoglycemia.

What interacts with Januvia?

Like all drugs, Januvia can cause problems when taken with other drugs. As a general rule , always keep a list of all the drugs you take including prescription drugs, over-the-counter medications, and even dietary supplements and herbal remedies. To prevent drug interactions, always share this list with healthcare providers when getting a prescription.

Fortunately, drug interactions with Januvia are comparatively mild. The most significant drug interactions involve diabetes medications, particularly insulin and insulin secretagogues (drugs that increase insulin secretion such as sulfonylureas and meglitinides). Although Januvia is frequently prescribed with other diabetic medications, any combination drug therapy does increase the risk of hypoglycemia. 

Other DPP-4 diabetic medications, however, are avoided in combination with Januvia. 

What happens when you mix Januvia and alcohol?

Healthcare professionals generally advise people on diabetic medications like Januvia to limit their alcohol intake. Alcohol reduces the body’s ability to make glucose, so combining alcohol with diabetic medications can cause low blood sugar. Januvia is less likely to cause hypoglycemia because it stops working when blood sugar is low, but it is frequently taken with other diabetic medications that don’t stop working when blood sugar is low. The best advice is to stay away from alcohol, but if you drink, do it moderately and on a full stomach to reduce the risk of hypoglycemia. 

Is it safe to take Januvia during pregnancy?

For pregnant women, the risk of birth defects or miscarriage when taking Januvia is unknown, but uncontrolled blood sugar is a known risk to both the mother and fetus. Pregnant women are urged to seek medical advice about the pros and cons of taking Januvia while pregnant. If Januvia is taken while pregnant, women are encouraged to register with the Januvia pregnancy registry to track any adverse reactions. 

There are no studies of Januvia’s effects on lactation or a nursing baby. It is unknown if sitagliptin is present in human breast milk. Mothers should seek medical advice from a healthcare professional about the risks and benefits of taking Januvia while breastfeeding.

Related resources for Januvia dosages:

• Januvia, Epocrates

• Januvia prescribing information, U.S. National Library of Medicine

• Januvia HCP, Merck & Co., Inc.

• Januvia tablets, Merck & Co., Inc.

• Review of sitagliptin phosphate: A novel treatment for Type 2 diabetes, Vascular Health and Risk Management

• Sitagliptin drug summary, Prescriber’s Digital Reference

• Sitagliptin: Is it effective in routine clinical practice?, International Journal of Endocrinology