Common side effects of HCTZ may include dizziness, upset stomach and headache, as listed by WebMD. HCTZ may also cause dehydration and a loss of salts and minerals in the body.
Side effects normally go away as the patient's body adjusts to the medication, and patients can decrease lightheadedness and dizziness by rising slowly after sitting or lying down, according to WebMD. Patients should notify their doctor if side effects worsen or persist. If patients experience serious side effects such as eye pain, decreased vision, muscle cramps, irregular heartbeat or decreased urination, they should contact a medical professional immediately. Other uncommon-but-serious side effects include excessive thirst or dry mouth and muscle weakness.
In the case of a rare but serious allergic reaction to HCTZ, the patient should seek immediate medical attention, says WebMD. Signs of an allergic reaction may include difficulty breathing, severe dizziness, rash, swelling and itching. Individuals should speak with a doctor before taking HCTZ if they have a history of gout, liver disease, kidney disease, diabetes or lupus. Due to the medication's tendency to make the user dizzy, patients should not operate heavy machinery or drink excessively while taking HCTZ. Patients should also consume foods high in potassium as the medication may deplete potassium levels.