Sitagliptin (Januvia): uses, side effects and cautions

Sitagliptin is a DPP-4 inhibitor. After you eat, the gut releases incretin hormones (GLP-1 and GIP) that tell the pancreas to release insulin. DPP-4 is the enzyme that breaks those hormones down quickly. The emc information explains that sitagliptin blocks this breakdown, raising the active hormones. Because the effect depends on glucose, insulin release is boosted when sugar is high and glucagon is reduced, which is why the drug is not expected to cause low sugar by itself.

The NHS puts it in plain terms: it increases insulin in your body to lower your blood sugar. It may be used alone or added to other diabetes medicines, including metformin, a sulfonylurea, a thiazolidinedione or insulin.

The NHS describes a once-daily tablet swallowed whole with water, at a consistent time, with or without food and usually for the long term. The emc standard dose is a single tablet daily, reduced when kidney filtration is lower: the SmPC specifies lower strengths for moderate and severe kidney impairment, including dialysis. Kidney function is checked before starting and periodically.

If you forget a dose, the NHS says take it when you remember unless the next dose is close, then skip it. Never double up.

The NHS lists headache when used alone, and hypoglycaemia when combined with other diabetes medicines, plus possible drowsiness or blurred vision. The SmPC adds uncommon dizziness, constipation and itching, and rare low platelets. Rare serious effects reported after launch include acute pancreatitis, allergic reactions including anaphylaxis and angioedema, Stevens-Johnson syndrome, bullous pemphigoid, interstitial lung disease and joint pain.

The warning sign for pancreatitis is persistent, severe abdominal pain. The NHS advises calling 999 for suspected pancreatitis, anaphylaxis or Stevens-Johnson syndrome. Sitagliptin is stopped if pancreatitis is suspected and not restarted if it is confirmed.

• Call 999: severe abdominal pain that does not go away, swollen lips or throat, or a spreading painful skin rash with blisters.

• Report blistering skin conditions, as bullous pemphigoid leads to stopping treatment.

The NHS lists previous allergy to sitagliptin, gallstones or alcohol use disorder, and liver or kidney problems as reasons for caution or avoidance. The SmPC treats type 1 diabetes and diabetic ketoacidosis as contraindications and says it is not used in children aged ten to seventeen because of limited efficacy.

The NHS names insulin, metformin, gliclazide and digoxin as medicines that may need dose changes. The SmPC says metformin has no meaningful interaction, digoxin exposure rises slightly (monitor people at risk of toxicity), and warfarin, simvastatin and oral contraceptives are unaffected. Alcohol can affect blood sugar, so the NHS advises avoiding it, and consistent meal timing matters.

Both sources advise against sitagliptin in pregnancy and breastfeeding, so doctors choose alternatives. Dizziness and sleepiness have been reported, so do not drive if affected, and take extra care about hypoglycaemia when combined with insulin or a sulfonylurea.

Sitagliptin is prescription only. The NHS gives Januvia as the brand name, and emc lists it in 25, 50 and 100 mg strengths. Report suspected side effects through the Yellow Card scheme.