What are the most common side effects of hydrochlorothiazide?
The most common side effects of hydrochlorothiazide are listed below. Tell your healthcare provider if you have any of these side effects that bother you.
- Low blood pressure (see below)
- Electrolyte changes and increased blood sugar (see below)
- An increase in how much you pee
There may be other side effects of hydrochlorothiazide that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.
What are the serious side effects of hydrochlorothiazide?
While less common, the most serious side effects of hydrochlorothiazide are described below, along with what to do if they happen.
Low Blood Pressure with Worsening Kidney Function. Water loss from hydrochlorothiazide can lower your blood pressure too much and cause dehydration. Both may lead to problems that are more serious than light-headedness. Poor blood flow to important organs such as your kidneys can occur, especially if you are elderly. Drink enough water to stay hydrated, especially if you have excess sweating, vomiting, or diarrhea. Get out of bed or from a seated position slowly. Tell your healthcare provider right away if you have any of the following symptoms.
- Dizziness, feeling lightheaded, or fainting
- Confusion
- Feeling weak or tired
- Sudden weight gain
- Confusion
- Reduced need to pee
- Increased thirst
- Dark or strong-smelling pee
- Dry mouth
- Sunken eyes
- Headache
- Fast heartbeat
Electrolyte Changes and Increased Blood Sugar. Hydrochlorothiazide may increase your blood sugar (glucose) levels and cause changes to the levels of certain minerals in your body, called electrolytes. For example, it may cause low potassium levels (hypokalemia), low sodium levels (hyponatremia), low magnesium levels (hypomagnesemia), high calcium levels (hypercalcemia), or low chloride levels (hypochloremia), or high glucose levels (hyperglycemia). These changes can be serious. Your healthcare provider will do bloodwork to check your glucose and electrolyte levels, especially if you take certain other medicines. Keep your appointments to have your blood checked. Call your healthcare provider if you have any of the following symptoms.
- Weakness
- Unusual tiredness
- Muscle cramps or twitching
- Constipation
- Nausea, vomiting, or loss of appetite
- Dizziness
- Restlessness or irritability
- Difficulty breathing
- Confusion or decreased alertness
- Abnormal heart rhythm
- Seizures
Short-Sightedness and Glaucoma. Hydrochlorothiazide may make it harder to see faraway objects (short-sightedness). It also may increase pressure inside the eye and cause or worsen narrow-angle glaucoma, which can lead to blindness. These issues may be more likely with taking hydrochlorothiazide if you have a sulfa or penicillin allergy. Tell your healthcare provider right away if you have any of the following symptoms.
- Trouble seeing faraway objects
- Loss of vision
- Eye pain or redness
- Severe headache or vomiting
- Seeing bright, colorful circles around lights (vision halos)
Severe Allergic Reactions. Hydrochlorothiazide may cause allergic reactions, which can be serious. Stop using hydrochlorothiazide and get help right away if you have any of the following symptoms of a serious allergic reaction.
- Breathing problems or wheezing
- Racing heart
- Fever or general ill feeling
- Swollen lymph nodes
- Swelling of the face, lips, mouth, tongue, or throat
- Trouble swallowing or throat tightness
- Itching, skin rash, or pale red bumps on the skin called hives
- Nausea or vomiting
- Dizziness, feeling lightheaded, or fainting
- Stomach cramps
- Joint pain
Severe Skin Reactions. Hydrochlorothiazide can cause severe skin reactions called Stevens-Johnson Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) that can lead to death if not treated. If you develop a rash, stop hydrochlorothiazide and call your healthcare provider right away. Get emergency help right away if you have any of the following symptoms of SJS or TEN.
- Painful red or purple skin that looks burned and peels off
- Flat red rash or blisters on your skin, mouth, nose, and genitals
- Red, painful, watery eyes
Inflammation of the Pancreas (Pancreatitis). Hydrochlorothiazide may cause inflammation of the pancreas, which is called pancreatitis. Stop taking hydrochlorothiazide and call your healthcare provider right away if you have symptoms of pancreatitis, including vomiting or severe pain in the upper part of your belly that travels to your back.
Liver Damage. Liver damage, also called hepatotoxicity, can happen when taking hydrochlorothiazide. Call your healthcare provider right away if you have any of the following symptoms of liver damage.
- Nausea or vomiting
- Stomach or belly pain
- Fever
- Weakness or unusual tiredness
- Itching
- Loss of appetite
- Light-colored poop
- Dark-colored urine
