Sitagliptin is a medicine used to treat type 2 diabetes. Type 2 diabetes is an illness where the body does not make enough insulin, or the insulin that it makes does not work properly.

This can cause high blood sugar levels (hyperglycaemia).

Sitagliptin is prescribed for people who still have high blood sugar, even though they have a sensible diet and exercise regularly.

Sitagliptin is only available on prescription.

It comes as tablets that you swallow. It also comes as tablets containing a mixture of sitagliptin and metformin. Metformin is another drug used to treat diabetes.

• Sitagliptin works by increasing the amount of insulin that your body makes. Insulin is the hormone that controls sugar levels in your blood.
• You take sitagliptin once a day.
• The most common side effect of sitagliptin is headaches.
• This medicine does not usually make you put on weight.
• Sitagliptin is also called by the brand name Januvia. When combined with metformin it's called Janumet.

Sitagliptin can be taken by adults (aged 18 years and older).

Sitagliptin is not suitable for some people. To make sure it's safe for you, tell your doctor if you:

• have had an allergic reaction to sitagliptin or any other medicines in the past
• have problems with your pancreas
• have gallstones or very high levels of triglycerides (a type of fat) in your blood
• are a heavy drinker or dependent on alcohol
• have (or have previously had) any problems with your kidneys
• are pregnant or breastfeeding, or trying to get pregnant

This medicine is not used to treat type 1 diabetes (when your body does not produce insulin).

Take sitagliptin once a day.

You can take it at any time - for example, in the morning or in the evening. Just try to take it at the same time every day.

Take your tablet with a glass of water. Swallow the tablet whole, without breaking it.

You can take sitagliptin with or without food.

How much will I take?

Sitagliptin comes as 25mg, 50mg and 100mg tablets.

The usual dose is 100mg a day.

Your doctor might give you a lower dose of 25mg or 50mg a day if you have problems with your kidneys.

What if I take too much?

What if I forget to take it?

Take the missed dose as soon as you remember, unless it's nearly time for your next dose.

In this case, skip the missed dose and take your next dose at the usual time.

Do not take a double dose to make up for a forgotten one.

If you forget doses often, it may help to set an alarm to remind you.

You could ask your pharmacist for advice on other ways to remember your medicines.

Like all medicines, sitagliptin can cause side effects in some people.

But many people have no side effects, or only minor ones.

Common side effects

The most common side effects, which happen in more than 1 in 100 people, are headaches.

Talk to your doctor if headaches last longer than a week or are severe.

If taking sitagliptin gives you a headache, make sure you rest and drink plenty of fluids. Do not drink too much alcohol.

Ask your pharmacist to recommend a painkiller.

Serious side effects

It happens rarely, but some people may have serious side effects after taking sitagliptin.

Call your doctor straight away if you have:

• severe stomach pains
• yellowing of your skin, or the whites of your eyes turn yellow

Low blood sugar

Sitagliptin does not usually cause low blood sugar (known as hypoglycaemia, or "hypos") when taken on its own.

But hypos can happen when you take sitagliptin with other diabetes medicines, such as insulin or gliclazide.

Early warning signs of low blood sugar include:

• feeling hungry
• trembling or shaking
• sweating
• confusion
• difficulty concentrating

It's also possible for your blood sugar to go too low while you're asleep.

If this happens, it can make you feel sweaty, tired and confused when you wake up.

Low blood sugar may happen if you:

• take too much of some types of diabetes medicines
• eat meals irregularly or skip meals
• are fasting
• do not eat a healthy diet and are not getting enough nutrients
• change what you eat
• increase your physical activity without eating more to compensate
• drink alcohol, especially after skipping a meal
• take some other medicines or herbal medicines at the same time
• have a hormone disorder, such as hypothyroidism
• have kidney or liver problems

It's important to have regular meals, including breakfast, to prevent hypoglycaemia. Never miss or delay a meal.

If you're planning to exercise more than usual, make sure you eat carbohydrates like bread, pasta or cereals before, during or after exercise.

Always carry a fast-acting carbohydrate with you, like sugar cubes, fruit juice or some sweets, in case your blood sugar level gets low. Artificial sweeteners will not help.

You may also need to eat a starchy carbohydrate, like a sandwich or a biscuit, to maintain your blood sugar for longer.

If taking in sugar does not help or the hypo symptoms come back, contact your doctor or the nearest hospital.

Make sure your friends and family know about your diabetes and the symptoms of low blood sugar levels so they can recognise a hypo if it happens.

Serious allergic reaction

It's possible to have a serious allergic reaction (anaphylaxis) to sitagliptin.

These are not all the side effects of sitagliptin.

For a full list, see the leaflet inside your medicines packet.

Sitagliptin is generally not recommended in pregnancy or while breastfeeding.

Talk to your doctor, as there may be other medicines you can take instead of sitagliptin.

Some medicines and sitagliptin can interfere with each other.

Some can increase your risk of getting side effects.

Tell your doctor if you're taking:

• insulin or any other anti-diabetic medicine
• ketoconazole or itraconazole (medicines for fungal infections)
• ritonavir (medicine used in treating HIV/AIDS)
• clarithromycin (antibiotic for treating pneumonia and ear infections)
• digoxin (medicine for heart conditions, including heart failure)

Make sure that your doctor and pharmacist know you're taking sitagliptin before starting or stopping any other medicine.

Mixing sitagliptin with herbal remedies and supplements

There's very little information about taking herbal remedies and supplements with sitagliptin.