Hyzaar may cause extremely low blood pressure in some people. Extremely low blood pressure is more likely to happen when the medicine is first started or the dosage is changed. It is also more likely to happen in people who are taking a diuretic, who are on dialysis, who have congestive heart failure, who have diarrhea or vomiting, or who have excessive sweating. This is why it is important to drink fluids regularly while taking Hyzaar. If you have any possible symptoms of low blood pressure, such as dizziness, light-headedness, or fainting, contact your healthcare provider. If you have fainted, stop taking Hyzaar until you have talked to your healthcare provider.
Also, make sure not to drive, operate any heavy machinery, or perform any other tasks that require alertness before you know how Hyzaar affects you.
Hyzaar is a pregnancy Category C medicine for the first trimester and a pregnancy Category D medicine for the second and third trimesters, meaning that Hyzaar poses health risks to your unborn child. Let your healthcare provider know if you are pregnant or thinking of becoming pregnant. If you become pregnant while taking Hyzaar, contact your healthcare provider immediately (see Hyzaar and Pregnancy for more information).
While taking Hyzaar, do not use potassium supplements or salt substitutes with potassium unless you have discussed this with your doctor. This is because in some people taking Hyzaar, potassium in the blood can increase or decrease to dangerous levels.
Hyzaar may affect electrolytes in the blood (including sodium, potassium, magnesium, and chloride). Therefore, your healthcare provider will regularly check these levels. If you notice any symptoms of a possible electrolyte imbalance, contact your healthcare provider. These symptoms may include a dry mouth, increased thirst, weakness, tiredness, restlessness, seizures, confusion, muscle pain or cramps, decrease in urine output, weak or irregular heartbeat, nausea, or vomiting.
Medicines like Hyzaar have been known to cause a decrease in kidney function, especially in certain groups (such as those with severe congestive heart failure). Let your healthcare provider know if you have symptoms such as a decrease in urine output, drowsiness, headache, or back pain. Your healthcare provider will also regularly check your kidney function with a blood test.
Because of the hydrochlorothiazide, Hyzaar is more likely than other drugs to cause allergic reactions. This is more common in people with a history of allergies or asthma. Make sure to discuss this risk with your healthcare provider. Also, seek emergency medical attention immediately if you notice things such as hives, an unexplained rash, difficulty breathing, or swelling of the face or throat.
Because of the hydrochlorothiazide, Hyzaar is more likely to worsen systemic lupus erythematosus or, in some cases, even cause the condition.
Because of the hydrochlorothiazide, Hyzaar is also known to worsen gout.
Hyzaar may cause high blood sugar (hyperglycemia) in diabetics or, in some cases, even cause diabetes in people without a history of the condition.
If you are nursing, it is not known whether Hyzaar passes through your breast milk. Therefore, if you are nursing, talk with your healthcare provider about whether you should stop taking Hyzaar or stop breastfeeding.