Known brand names include No current brand name for single-agent tablets or capsules; marketed as generic hydrochlorothiazide (HCTZ). RxNorm brands are mostly combination products, plus Inzirqo, an oral suspension outside this scope..
A thiazide "water pill" that helps the kidneys remove extra salt and water. It treats high blood pressure and swelling from heart, liver, or kidney disease or from steroid or estrogen therapy.
Hydrochlorothiazide acts on the distal tubules of the kidneys, where salt is normally taken back into the body. It blocks some of that uptake, so more sodium and chloride leave in the urine, and water goes with them. Some potassium and bicarbonate are lost as well. Exactly how it lowers blood pressure is not known.
Taken by mouth, it starts increasing urine within 2 hours, reaches its peak around 4 hours, and keeps working for about 6 to 12 hours. It does not usually lower blood pressure that is already normal. Because it washes out salt and potassium, it can drop blood sodium and potassium too low, which may cause thirst, weakness, cramps, or confusion. In people with weak kidneys, its effects can build up.
Hydrochlorothiazide is a water pill that lowers high blood pressure. Untreated high blood pressure can damage the brain, heart, blood vessels, and kidneys and lead to heart attack, stroke, or kidney failure. It also helps clear edema, extra fluid held in the body's tissues, as an added treatment. The fluid may come from heart failure, liver scarring, kidney disease, or treatment with steroids or estrogen.
It is taken by mouth as a tablet or capsule, either alone or with other blood pressure medicines for more severe high blood pressure. It controls blood pressure but does not cure it. In pregnancy, it is used only for swelling caused by an illness, and routine use during a normal pregnancy is not appropriate. It is not used by people whose kidneys have stopped making urine or who are allergic to sulfa-type drugs.
Low potassium, sodium, and magnesium, dizziness when standing up, higher blood sugar, gout flares, and skin that burns easily in the sun are the common effects. It can also raise calcium and cholesterol slightly and raise the risk of some skin cancers. The label treats sudden vision changes and eye pain from a type of glaucoma as serious, along with kidney or liver problems getting worse, pancreatitis, blood disorders, severe skin reactions, and lupus flares.