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Istin (amlodipine) is a medication that is used to treat high blood pressure (hypertension). It helps make it easier for the heart to pump the blood around the body by dilating the blood vessels. Istin comes in the form of tablets and is only available on prescription.

What is Istin?

Istin treats hypertension (high blood pressure) and is the brand name for amlodipine, the active ingredient in this medication. It can be used by adults and children over six years of age, on the advice of a doctor.

Blood pressure is the strength of the blood against the sides of the vessels that move around the body (the arteries). The heart pumps the blood to give it oxygen and energy. Blood pressure goes up and down throughout the day depending on your activity. When you first wake and get up in the morning your blood pressure is relatively low. It will then change during the day. If your blood pressure is continually high, even when resting, you should see a doctor as this may mean you have hypertension and need medication.

High blood pressure puts extra strain on the heart and arteries and can cause heart disease, heart attacks and strokes which can all be life-threatening. In a person with normal blood pressure, the arteries are flexible to assist the flow of blood around the body. When a person has high blood pressure the arteries can become stiff or narrow and can become clogged with fatty material, which can affect the flow of blood. This is also why eating fatty food can block arteries and cause heart disease.

Some of the risk factors for high blood pressure are:

  • Getting older;
  • Being overweight or obese;
  • Leading an inactive lifestyle;
  • Drinking excessive alcohol;
  • Using recreational drugs;
  • Family history – if a parent, grandparent or sibling have high blood pressure you are at risk of developing it;
  • Stress and anxiety;
  • Having diabetes;
  • Having kidney disease;
  • Having a hormonal condition such as thyroid disease, pituitary disease or adrenal disease;
  • Suffering from sleep apnea;
  • Genetics;
  • Gender – hypertension is more common for men until the age of 45. Then, the likelihood of developing high blood pressure is the same in both men and women until the age of 64 and more likely in women aged 60 and over;
  • Race – black and white people are more likely to suffer from high blood pressure than Latin and Asian people;
  • Smoking.

A heart attack can take place when an artery is blocked and the blood supply to the heart is cut off. Part of the heart muscles then dies. A stroke is when the blood supply to part of the brain is cut off which causes that part of the brain to stop working, sometimes permanently. According to the British Heart Foundation, approximately 50 per cent of heart attacks and strokes are caused by high blood pressure. This could be avoided if a person is aware they have high blood pressure and take the necessary action to reduce it.

As well as medication, a healthy lifestyle also contributes to keeping the blood pressure at the right level.

You may not be aware you have high blood pressure as there are often no symptoms. The best way to assess if you have a high blood pressure problem is to have your blood pressure checked regularly over a period of weeks. If it is abnormally high it can be controlled by the use of medication, such as Istin. Note that Istin should not be taken in conjunction with other blood pressure medications as this can reverse its effect.

You do not have to visit a doctor to monitor your own blood pressure. Many pharmacies offer this service or you can purchase your own blood pressure monitor to use in the comfort of your own home. However, if you are concerned that you may have high blood pressure or receive a constant high reading you should see your doctor.

There are two readings of blood pressure. The first is known as the systolic pressure, which is the highest pressure at which your heart beats and pumps the blood around your body. The second number is the diastolic pressure, which is the lowest pressure, when your heart relaxes in between beats. The ideal blood pressure for a healthy heart is 120/80.

Istin is used to reduce the blood pressure which can be the cause of the above severe or fatal illnesses. It works by enlarging the blood vessels, which allows the blood to flow around the body more easily.

When is Istin used?

Istin tablets are used to treat and manage high blood pressure and the pain caused by heart conditions such as angina (pain in the chest caused by poor blood flow to the heart muscles). If you are prescribed Istin you may have to take it for the whole of your life to treat a particular heart ailment. It should be used in conjunction with a healthy lifestyle which should include regular exercise, healthy eating and weight control.

How do you use Istin?

Istin medication should be taken on the advice of a doctor. To keep blood levels even and reduce blood pressure, one Istin tablet per day is taken with or without food. The tablet should not be chewed. It can also be dissolved in water and the solution must be drunk immediately.

Try and take your Istin tablet at approximately the same time every day to keep your blood pressure levels even.

Istin tablets should not be taken with grapefruit juice or grapefruit as it can affect how it works and can increase the levels of amlodipine (the active ingredient) in the blood. This can cause an increase in blood pressure, which has the reverse effect of Istin tablets.

You should not increase your dose of Istin medication without consulting a doctor.

You should still continue to take Istin if you feel well as it is a long-term medication to reduce your blood pressure. You should take Istin for as long as your doctor prescribes it.

If you miss a dose, do not take another to make up for it. You should wait and take the next tablet at the usual time. Istin is suitable for adults and children over 6 years of age.

What dosages are there?

Istin comes in 5 mg and 10 mg tablets. The usual dose is:

  • Adults – one 5 mg or 10 mg tablet per day;
  • Children aged 6 years and above – half or one whole 5 mg tablet per day.

Your doctor will prescribe the dose most appropriate to your symptoms. They may decide to change the dose after you have taken Istin for a while, depending on your blood pressure readings.

What are the side effects of Istin?

The most common side effects of Istin can be:

  • Pounding heart;
  • Headaches;
  • Feeling tired;
  • Flushing;
  • Feeling dizzy;
  • Swollen ankles (edema/fluid retention);
  • Muscle cramps.

If any of the above occurs after taking Istin and you are concerned you should consult a doctor. It is advisable not to drink alcohol while you are taking Istin as it could make the side effects of this medication worse. If Istin makes you dizzy or drowsy do not drive or operate machinery as this could be dangerous, both to you and other people.

When shouldn’t you use Istin?

Do not use this medication if you are allergic to amlodipine or any of the other ingredients in Istin. Consult the packaging leaflet for more information.

You should not take this medicine if you:

  • Have recently had a heart attack or heart failure;
  • Have low blood pressure (hypotension);
  • Have narrowing of the aortic heart valve;
  • Have cardiogenic shock (when the heart cannot supply enough blood to the body).

It is also important to inform your doctor before taking Istin if you:

  • Have liver disease;
  • Have kidney disease;
  • Are pregnant or planning to become pregnant;
  • Are breastfeeding.

Your doctor will then decide if this medicine is appropriate for you, depending on your circumstances. You should not take Istin with grapefruit juice or eat grapefruit when taking it.

Does Istin interact with other medications?

Istin can interact with other medications so it is important to inform your doctor of any other medication you are taking. This includes herbal medicines and in particular St John’s Wort, which can be taken for depression.

Istin can react with other blood-pressure-reducing medicines and can lower your blood pressure and make you feel dizzy or cause serious symptoms. Therefore it is important to tell your doctor about any medication you are taking.

Where can you buy Istin?

Istin is a prescription-only medicine and is not available over-the-counter. You must get a prescription from your doctor to buy Istin.

Can I get Istin without a prescription?

No, you must have a prescription to get Istin tablets.


Amlodipine. December 18, 2018. Retrieved 7 January, 2020 from High blood pressure. British Heart Foundation. (N.D.). Retrieved 7 January, 2020 from

Wedro, B. 7 November, 2019. Stroke. Retrieved 7 January, 2020 from

Stibich, M. 4 December, 2019. Causes and Risk Factors of Hypertension. Retrieved 7 January, 2020 from

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Reviewed by:

Dr Imran Malik, General practitioner Registrationnumber: GMC: 4741365 Last checked: 17-03-2022 | Still valid

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