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Isentress 400 mg Film-coated Tablets

Active Ingredient:
raltegravir potassium
Merck Sharp & Dohme (UK) Limited See contact details
ATC code: 
About Medicine
The Patient Information Leaflet (PIL) is the leaflet included in the pack with a medicine.
Last updated on emc: 29 Mar 2023

Below is a text only representation of the Patient Information Leaflet (ePIL).

The text only version may be available in large print, Braille or audio CD. For further information call emc accessibility on {phone} 0800 198 5000. The product code(s) for this leaflet is: PLGB 53095/0032.

Isentress 400 mg Film-coated Tablets

Package leaflet: Information for the user

Isentress® 400 mg film-coated tablets


Read all of this leaflet carefully before you start taking this medicine because it contains important information for you.

If you are the parent of a child taking Isentress, please read this information carefully with your child.

  • Keep this leaflet. You may need to read it again.
  • If you have any further questions, ask your doctor, pharmacist or nurse.
  • This medicine has been prescribed for you or your child only. Do not pass it on to others. It may harm them, even if their signs of illness are the same as yours.
  • If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. See section 4.

What is in this leaflet

1. What Isentress is and what it is used for
2. What you need to know before you take Isentress
3. How to take Isentress
4. Possible side effects
5. How to store Isentress
6. Contents of the pack and other information

1. What Isentress is and what it is used for
What Isentress is

Isentress contains the active substance raltegravir. Isentress is an antiviral medicine that works against the Human Immunodeficiency Virus (HIV). This is the virus that causes Acquired Immune Deficiency Syndrome (AIDS).

How Isentress works

The virus produces an enzyme called HIV integrase. This helps the virus to multiply in the cells in your body. Isentress stops this enzyme from working. When used with other medicines, Isentress may reduce the amount of HIV in your blood (this is called your "viral load") and increase your CD4-cell count (a type of white blood cells that plays an important role in maintaining a healthy immune system to help fight infection). Reducing the amount of HIV in the blood may improve the functioning of your immune system. This means your body may fight infection better.

When Isentress should be used

Isentress is used to treat those who are infected by HIV. Your doctor has prescribed Isentress to help control your HIV infection.

2. What you need to know before you take Isentress
Do not take Isentress:
  • If you are allergic to raltegravir or to any of the other ingredients in this medicine (listed in section 6).

Warnings and precautions

Talk to your doctor, pharmacist or nurse before taking Isentress.

Remember that Isentress is not a cure for HIV infection. This means that you may keep getting infections or other illnesses associated with HIV. You should keep seeing your doctor regularly while taking this medicine.

Mental health problems

Tell your doctor if you have a history of depression or psychiatric illness. Depression, including suicidal thoughts and behaviours, has been reported in some patients taking this medicine, particularly in patients with a prior history of depression or psychiatric illness.

Bone problems

Some patients taking combination anti-retroviral therapy may develop a bone disease called osteonecrosis (death of bone tissue caused by loss of blood supply to the bone). The length of combination anti-retroviral therapy, corticosteroid use, alcohol consumption, severe reduction of the activity of the immune system, higher body mass index, among others, may be some of the many risk factors for developing this disease. Signs of osteonecrosis are joint stiffness, aches and pains (especially of the hip, knee and shoulder) and difficulty in movement. If you notice any of these symptoms, please inform your doctor.

Liver problems

Tell your doctor, pharmacist or nurse if you have had problems with your liver before, including hepatitis B or C. Your doctor may evaluate how severe your liver disease is before deciding if you can take this medicine.


Tell your doctor, pharmacist or nurse immediately if you notice any symptoms of infection, such as fever, and/or feeling unwell. In some patients with advanced HIV infection and a history of opportunistic infection, signs and symptoms of inflammation from previous infections may occur soon after anti-HIV treatment is started. It is believed that these symptoms are due to an improvement in the body’s immune response, enabling the body to fight infections that may have been present with no obvious symptoms.

In addition to the opportunistic infections, autoimmune disorders (a condition that occurs when the immune system attacks healthy body tissue) may also occur after you start taking medicines for the treatment of your HIV infection. Autoimmune disorders may occur many months after the start of treatment. If you notice any symptoms of infection or other symptoms such as muscle weakness, weakness beginning in the hands and feet and moving up towards the trunk of the body, palpitations, tremor or hyperactivity, please inform your doctor immediately to seek necessary treatment.

Muscle problems

Contact your doctor, pharmacist or nurse immediately if you experience unexplained muscle pain, tenderness, or weakness while taking this medicine.

Skin problems

Contact your doctor promptly if you develop a rash. Severe and life-threatening skin reactions and allergic reactions have been reported in some patients taking this medicine.

Other medicines and Isentress

Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines with or without a prescription.

Isentress might interact with other medicines.

Tell your doctor, pharmacist or nurse if you are taking, have recently taken or might take:

  • antacids (an agent that counteracts or neutralises the acid in the stomach to relieve indigestion and heartburn). It is not recommended to take Isentress with certain antacids (those containing aluminium and/or magnesium). Talk to your doctor about other antacids you can take.
  • iron salts (to treat and prevent iron deficiency or anaemia). You should wait at least two hours between taking iron salts and taking Isentress, as these medicines may reduce Isentress efficacy.
  • rifampicin (a medicine used to treat some infections such as tuberculosis), as it may decrease your levels of Isentress. Your doctor may consider increasing your dose of Isentress if you are taking rifampicin.

Taking Isentress with food and drink

See section 3.

Pregnancy and breast-feeding

If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine.

  • Breast-feeding is not recommended in women living with HIV because HIV infection can be passed on to the baby in breast milk.
  • If you are breast-feeding, or thinking about breast-feeding, you should discuss it with your doctor as soon as possible.

Ask your doctor, pharmacist or nurse for advice before taking any medicine if you are pregnant or breast-feeding.

Driving and using machines

Do not operate machines, drive or cycle if you feel dizzy after taking this medicine.

Isentress contains lactose

This medicine contains lactose. If you have been told by your doctor that you have an intolerance to some sugars, contact your doctor before taking this medicine.

Isentress contains sodium

This medicine contains less than 1 mmol sodium (23 mg) per tablet, that is to say essentially ‘sodium-free’.

3. How to take Isentress

Always take this medicine exactly as your doctor, pharmacist or nurse has told you. You should check with your doctor, pharmacist or nurse if you are not sure. Isentress must be used in combination with other medicines for HIV.

How much to take


The recommended dose is 1 tablet (400 mg) by mouth twice a day.

Use in children and adolescents

The recommended dose of Isentress is 400 mg by mouth, twice a day for adolescents and children weighing at least 25 kg.

Do not chew, crush or split the tablets because it may change the level of medicine in your body. This medicine can be taken with or without food or drink.

Isentress is also available in a 600 mg tablet, a chewable tablet and in granules for oral suspension. Do not switch between the 400 mg tablet, the 600 mg tablet, chewable tablet or granules for oral suspension without first talking with your doctor, pharmacist or nurse.

If you take more Isentress than you should

Do not take more tablets than the doctor recommends. If you do take too many tablets, contact your doctor.

If you forget to take Isentress
  • If you forget to take a dose, take it as soon as you remember it.
  • However, if it is time for your next dose, skip the missed dose and go back to your regular schedule.
  • Do not take a double dose to make up for a forgotten dose.

If you stop taking Isentress

It is important that you take Isentress exactly as your doctor has instructed. Do not change the dose or stop taking this medicine without first talking with your doctor, pharmacist or nurse. Do not stop taking it because:

  • It is very important to take all your HIV medicines as prescribed and at the right times of day. This can help your medicines work better. It also lowers the chance that your medicines will stop being able to fight HIV (also called "drug resistance").
  • When your supply of Isentress starts to run low, get more from your doctor or pharmacy. This is because it is very important not to be without the medicine, even for a short time. During a short break in taking the medicine the amount of virus in your blood may increase. This may mean that the HIV virus will develop resistance to Isentress and become harder to treat.

If you have any further questions on the use of this medicine, ask your doctor, pharmacist or nurse.

4. Possible side effects

Like all medicines, this medicine can cause side effects, although not everybody gets them.

Serious side effects – these are uncommon (may affect up to 1 in 100 people)

See a doctor immediately, if you notice any of the following:

  • herpes infections including shingles
  • anaemia including due to low iron
  • signs and symptoms of infection or inflammation
  • mental disorder
  • suicide intention or attempt
  • stomach inflammation
  • inflammation of liver
  • liver failure
  • allergic rash
  • certain kinds of kidney problems
  • drug ingestion in quantities greater than recommended

See a doctor immediately, if you notice any of the side effects above.

Common: the following may affect up to 1 in 10 people

  • decreased appetite
  • trouble sleeping; abnormal dreams; nightmare; abnormal behaviour; feelings of deep sadness and unworthiness
  • feeling dizzy; headache
  • spinning sensation
  • bloating; abdominal pain; diarrhoea; excessive gas in the stomach or bowel; feeling sick; vomiting; indigestion; belching
  • certain kinds of rash (more often when used in combination with darunavir)
  • tiredness, unusual tiredness or weakness; fever
  • increased liver blood tests; abnormal white blood cells; increased fat levels in blood; increased level of enzyme from salivary glands or pancreas

Uncommon: the following may affect up to 1 in 100 people

  • infection of the hair roots; influenza; skin infection due to virus; vomiting or diarrhoea due to an infectious agent; upper respiratory tract infection; lymph node abscess
  • wart
  • lymph node pain; low count of white blood cells that fight infection; swollen glands in the neck, armpit and groin
  • allergic reaction
  • increased appetite; diabetes; increased blood cholesterol and lipids; high sugar levels in the blood; excessive thirst; severe weight loss; high levels of fat (such as cholesterol and triglycerides) in the blood; body fat disorder
  • feeling anxious; feeling of confusion; depressed mood; mood changes; panic attack
  • loss of memory; pain in the hand due to nerve compression; disturbance in attention; dizziness with rapid changes in posture; abnormal taste; increased sleepiness; lack of energy; forgetfulness; migraine headache; loss of feeling, numbness or weakness of the arms and/or legs; tingling; sleepiness; tension headache; tremors; poor quality sleep
  • visual disturbance
  • buzzing, hissing, whistling, ringing or other persistent noise in the ears
  • palpitations; slow heart rates; fast or irregular heart beats
  • hot flush; high blood pressure
  • harsh, raspy, or strained voice; nosebleed; nasal congestion
  • abdominal pain upper; rectal discomfort; constipation; dry mouth; heartburn; pain when swallowing; inflammation of the pancreas; ulcer or sore in stomach or upper intestine; bleeding at anus; stomach discomfort; inflammation of the gums; swollen, red sore tongue
  • accumulation of fat in the liver
  • acne; unusual hair loss or thinning; redness of skin; unusual distribution of fat on the body, this may include loss of fat from legs, arms, and face, and increase in abdomen fat; excessive sweating; night sweats; thickening and itching of the skin due to repeated scratching; skin lesion; dry skin
  • joint pain; painful joint disease; back pain; pain in bone/muscle; muscle tenderness or weakness; neck pain; pain in arms or legs; inflammation of the tendons; decrease in the amount of minerals in the bone
  • kidney stones; urination at night; kidney cyst
  • erectile dysfunction; breast enlargement in men; menopausal symptoms
  • chest discomfort; chills; swelling of face; feeling jittery; generally feeling unwell; neck mass; swelling of hands, ankles or feet; pain
  • decreased white blood cell count; decreased count of platelets in blood (a kind of cell that helps blood clot); blood test showing reduced kidney function; high blood sugar level; increased muscle enzyme in blood; sugar present in urine; red blood cells present in urine; weight gain; increase in waist size; decreased blood protein (albumin); increase in time for blood to clot

Additional side effects in children and adolescents

  • hyperactivity

Reporting of side effects

If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme at or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.

5. How to store Isentress
  • Keep this medicine out of the sight and reach of children.
  • Do not use this medicine after the expiry date which is stated on the bottle after EXP. The expiry date refers to the last day of that month.
  • This product does not require any special storage conditions.
  • Keep the bottle tightly closed, with the desiccant (drying agent) in order to protect from moisture. Do not swallow the desiccant.

Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help protect the environment.

6. Contents of the pack and other information
What Isentress contains

The active substance is raltegravir. Each film-coated tablet contains 400 mg of raltegravir (as potassium).

The other ingredients are: lactose monohydrate, microcrystalline cellulose, calcium phosphate dibasic anhydrous, hypromellose 2208, poloxamer 407, sodium stearyl fumarate, and magnesium stearate. In addition, the film coating contains the following inactive ingredients: polyvinyl alcohol, titanium dioxide, polyethylene glycol 3350, talc, red iron oxide and black iron oxide.

What Isentress looks like and contents of the pack

The 400 mg film-coated tablet is oval-shaped, pink, marked with "227" on one side. Two pack sizes are available: packs containing 1 bottle with 60 tablets, and multipacks comprising 3 bottles, each containing 60 tablets. The bottle contains desiccant.

Not all pack sizes may be marketed.

Marketing Authorisation Holder and Manufacturer

Marketing Authorisation Holder:

Merck Sharp & Dohme (UK) Limited
120 Moorgate
United Kingdom.


Merck Sharp & Dohme B.V.
Waarderweg 39
2031 BN Haarlem
The Netherlands

For any information about this medicine, please contact:

Merck Sharp & Dohme (UK) Limited
Tel: +44 (0) 208 154 8000

This leaflet was last revised in November 2022

© 2022 Merck & Co., Inc., Rahway, NJ, USA and its affiliates. All rights reserved.


Merck Sharp & Dohme (UK) Limited
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120 Moorgate, London, EC2M 6UR, UK
+44 (0)208 154 8000
Medical Information e-mail
[email protected]
Customer Care direct line
+44 (0)2081548001