Zestoretic tablets contain two active ingredients, lisinopril and hydrochlorothiazide. Lisinopril is a type of medicine called an ACE inhibitor. Hydrochlorothiazide is a type of medicine called a thiazide diuretic. These are both medicines used to lower high blood pressure.
ACE inhibitors such as lisinopril work by blocking the action of a compound in the body called angiotensin converting enzyme (ACE). Normally ACE produces another compound called angiotensin II, as part of the body's natural control of blood pressure. Angiotensin II causes blood vessels to constrict and narrow, which increases the pressure within the blood vessels.
As lisinopril blocks the action of ACE, it reduces the production of angiotensin II. This means that the blood vessels are allowed to relax and widen. The overall effect of this is a drop in blood pressure, hence lisinopril can be used to lower high blood pressure.
Diuretics such as hydrochlorothiazide are sometimes referred to as water tablets. They remove excess fluid from the body by increasing the production of urine.
Diuretics act in the kidneys. They work by causing the kidneys to increase the amount of salts, such as potassium and sodium, that are filtered out of the blood and into the urine. When these salts are filtered out of the blood by the kidneys, they draw water alongside them. As diuretics increase the removal of salts from the blood, they also cause more water to be drawn out of the blood and into the urine.
Removing water from the blood decreases the volume of fluid circulating through the blood vessels. This subsequently decreases the pressure within the blood vessels. Diuretics can therefore be used to lower high blood pressure.
The combination of lisinopril with hydrochlorothiazide is used when blood pressure has not been lowered sufficiently using lisinopril on its own.
This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.
Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.
Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.
The side effects listed above may not include all of the side effects reported by the medicine's manufacturer.For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.
It is important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, check with your doctor or pharmacist before taking any new medicines while taking this one, to ensure that the combination is safe.
This medicine will have an additive effect with other medicines that decrease blood pressure, particularly other medicines used to treat high blood pressure (antihypertensives). In people taking antihypertensive medicines it may cause a large drop in blood pressure with the first dose or after any dose increases, particularly in people taking diuretic medicines such as furosemide. This may cause dizziness, which can usually be relieved by lying down until the symptoms pass. If you frequently feel dizzy while taking this medicine in combination with other blood pressure lowering medicines you should let your doctor know, as your doses may need adjusting. Other medicines that decrease blood pressure include the following:
Non-steroidal anti-inflammatory drugs (NSAIDs, eg indometacin, aspirin, diclofenac, ibuprofen) may reduce the blood pressure lowering effect of this medicine, and may increase the risk of a decline in kidney function. You should avoid taking this type of painkiller unless recommended by your doctor.
There may be a risk of raised potassium levels in the blood (hyperkalaemia) if any of the following medicines are taken with lisinopril, hence these are not normally recommended for use in combination with this medicine. If you are taking any of the following with this medicine you should have regular blood tests to monitor the amount of potassium in your blood:
There may be a risk that the amount of potassium in the blood could fall too low (hypokalaemia) if any of the following medicines are taken in combination with this medicine:
This medicine may increase the blood level of the medicine lithium and for this reason, it is not normally recommended for people taking lithium. People taking this medicine in combination with lithium should have the level of lithium in their blood closely monitored.
Lisinopril may possibly enhance the blood sugar lowering effect of insulin and oral antidiabetic medicines, and so could increase the risk of low blood sugar (hypoglycaemia). On the other hand, hydrochlorothiazide may increase blood sugar levels. People with diabetes should therefore carefully monitor their blood sugar while taking this medicine, particularly in the first few weeks of treatment.
There may be an increased risk of a drop in the normal numbers of white blood cells in the blood if this medicine is taken in combination with any of the following medicines:
If you are taking any of these in combination with this medicine, you should have regular blood tests to monitor the levels of your blood cells, particularly if you also have any kidney problems or diseases affecting connective tissue, eg scleroderma, systemic lupus erythematosus or rheumatoid arthritis (collagen vascular diseases). Tell your doctor if you experience any signs of infection, such as fever, sore throat or mouth ulcers, as these could be signs of problems with your white blood cells.