From the digestive system: nausea, vomiting and sometimes diarrhea (when taking the drug before meals), pain and discomfort in the epigastric region, colicky abdominal pain, constipation, dry mouth, thirst, in single cases - hemorrhagic pancreatitis, and in the presence of gallstones - acute cholecystitis.
From the central nervous system: uncoordinated movements, drowsiness, fatigue, headache, nervousness.
From the side of the locomotive system: muscle tension, muscle weakness, cramps calf muscles.
From the cardiovascular system: palpitations, decreased blood pressure, cardiac arrhythmias and impaired blood circulation regulation with dizziness, confusion, or a tendency to faint. In connection with a large loss of fluid and a decrease in the volume of circulating blood, when using the drug in high doses and / or abundant urine release, thrombi may develop, embolism develop, in rare cases convulsions, confusion, vascular collapse, and acute renal failure.
From the side of metabolism: a temporary increase in the concentration of nitrogen-containing substances released by the kidneys (urea, Creatinine) in the blood (mainly at the beginning of treatment), disorders of fluid and electrolyte balance, mainly reduction of sodium, magnesium, chloride in blood, a reduction or an increase in the potassium content (with prolonged continuous use of the drug), hypercalcemia, reduced tolerance to glucose. It is possible to increase the content of uric acid in the blood, on the basis of which, in some particularly predisposed patients, gout attacks can be triggered, and the formation of urinary stones can be noted.In sensitive patients, depending on the accepted total dose of the drug, an increase in the lipid content in the blood can be observed. In connection with the increase in the concentration of glucose in the blood, the already existing form of diabetes mellitus may become latent or aggravate. The drug can promote the accumulation of nonvolatile acids in the blood (metabolic acidosis).
On the part of the organs of vision: visual impairment, worsening of already existing myopia or a decrease in the production of tear fluid.
On the part of the hematopoiesis system: aplastic anemia, leukopenia, thrombocytopenia, agranulocytosis, megaloblastic anemia with a previous folate deficiency in the body, hemolysis resulting from the appearance of autoantibodies to the active substance hydrochlorothiazide in the blood with the simultaneous use of methyldopa.
Allergic reactions: reddening of the skin, skin itching, urticaria, systemic lupus erythematosus, photoallergic exanthema, fever, hypersensitivity reactions (anaphylactoid reactions), severe inflammation of the blood vessels and non-bacterial inflammation of the kidney tissue (aseptic interstitial nephritis).In a few cases, a sudden development of pulmonary edema with symptoms of shock was described. The reason for this is probably the allergic reaction of patients to the active substance hydrochlorothiazide.
Other: icteric skin color, mucous membranes and sclera.