Chlorothiazide (oral)

Chlorothiazide is used in the treatment of people suffering from edema.


Chlorothiazide is a thiazide diuretic drug that can be used alone or with other medications to treat people suffering from edema. Some illnesses, including liver cirrhosis, kidney disease, and some forms of cancer can cause fluid retention (edema), as does treatment with certain hormone or steroid drugs. Chlorothiazide is also used to treat these side effects.

This drug is often prescribed for patients whose blood pressure is too high. Hypertension can place a higher burden on the arteries and heart of long-term sufferers, potentially leading to serious health problems such as heart failure, stroke, kidney failure, or heart attack. When the blood pressure is controlled, these conditions are much less likely to happen.

Chlorothiazide is sold under the brand name, Diuril in the US. You can only obtain Chlorothiazide on prescription from your doctor. The medicine is dispensed as a suspension or as tablets.

Chlorothiazide works by reducing the amount of fluid in the patient’s body. It does so by encouraging the body to produce more urine, thus lowering the blood pressure and getting rid of excess fluid. This medicine will not cure your condition, but it will help to control and manage it.

Conditions treated

• edema
• hypertension

Type of medicine

• tablet
• suspension
• thiazide diuretic

Side effects

Thiazide diuretics are designed to control and manage the symptoms of edema. However, it is possible that you may find that you have some unwanted side effects while you are using it.

Before you begin your course of chlorothiazide, tell your doctor if you have ever had any allergic reactions or side effects when taking any form of medicine. This includes over-the-counter products, vitamin supplements or herbal remedies. Remember to tell your doctor if you have any allergies to particular foodstuffs, animal derivatives, preservatives, or dyes.

The side effects given here are occasionally experienced by patients taking chlorothiazide. However, this list is not all-inclusive. Therefore, if you do notice anything odd about your behavior, or if you begin to feel unwell after starting your course of treatment with this drug, ask your GP for advice as soon as possible.

Tell your treating physician immediately if you experience any of the following side effects:

• white spots on lips or in the mouth, sores, or ulcers
• wheezing
• weakness in hands or feet, numbness, tingling or pain
• weakness and heaviness of legs
• vomiting of blood
• unusual tiredness or weakness
• unusual bleeding or bruising
• unpleasant breath odor
• unexpected weight loss
• unexpected weight gain
• trembling
• tingling, burning or other odd skin sensations
• tightness in chest
• thirstiness
• thickening of bronchial secretions
• tenderness of salivary glands
• swollen glands
• swelling or puffiness around the eyelids, eyes, face, lips, or tongue
• sugar in the urine
• stomach or abdominal pain
• sores, welting, or blisters
• sore throat
• seizures
• scaly skin
• red, swollen skin
• red, irritated eyes
• red skin lesions with a purple center
• pinpoint red spots on skin
• pains in your legs or back
• nosebleeds
• nausea or vomiting
• muscle cramp or pain
• loss of heat from the body
• loss of appetite
• loosening, blistering, or peeling of the skin
• joint pain, stiffness, or swelling
• jaundice
• indigestion
• increased urination
• increase in sweating
• increase in hunger
• increase in blood pressure
• hives
• headache
• general swelling of the body
• fruit-like breath odor
• flushed, dry skin
• fever
• feeling of tiredness or weakness
• feeling of discomfort or illness
• fast or irregular heartbeat
• faintness, dizziness, or lightheadedness when rising suddenly from a prone or seated position
• dry mouth
• difficulty swallowing
• difficult, fast, or noisy breathing
• diarrhea
• decreased frequency or amount of urine
• cyanosis
• coughing with a pink frothy sputum or blood
• cough or hoarseness
• constipation
• confusion
• cold sweats
• cloudy or dark urine
• clay-colored stools
• chills
• chest pains
• blurred vision
• blood in urine or stools
• bloating
• bleeding gums
• black, tarry stools

Some of the side effects that patients report while taking chlorothiazide do not require any further medical intervention and resolve themselves once the body gets used to the new drug.

Your GP may be able to suggest ways of reducing or preventing many of these effects. However, if any of these side effects become especially troublesome or do not resolve within a couple of weeks, ask your medical professional for assistance.

• weakness
• severe sunburn
• sensation of spinning
• restlessness
• muscle spasms
• increased sensitivity of the skin to sunlight
• inability to obtain or maintain an erection
• hair loss, or thinning
• feeling of constant movement of surroundings or self
• discoloration or reddening of skin
• difficulty having a bowel movement
• decreased libido
• cramps

If you have any other side effects that are not included in this list, check with your doctor immediately.

You must not abruptly stop taking your medication unless your doctor tells you to do so. This could cause severe side effects and could cause a sudden worsening in your condition. If your doctor decides to discontinue your treatment with chlorothiazide, you will be advised to gradually reduce your dose before you stop taking the drug completely.


The dose of chlorothiazide that you are given will not necessarily be the same for every patient. Be sure to take the drug as directed by your doctor or follow the directions given on the dispensary label. The information that follows is based on the average dose that is recommended for this drug. If the dose that you are told to take is different, do not change it unless you are told to by your GP.

The dose that your doctor prescribes for you will depend on a number of factors, including the potency of the preparation, your health condition, your age, and your body weight.

Before using the suspension form of the drug, shake the bottle well to ensure that the suspension is properly combined. When using the tablet form of the medicine, take the tablets whole, rather than sucking, chewing, or crushing them.

If you are prescribed the liquid form of chlorothiazide, you must measure it carefully, using a specifically designed medicine measuring device or spoon. You should avoid using an ordinary household teaspoon, as this may not be accurate, so your dose could be incorrect. Your doctor or pharmacist will be able to provide you with a suitable measuring device if one is not supplied with your prescription.

You can take the medication with or without food.

If you are dividing your dose of the medicine, try to take it at evenly spaced intervals during the day and at the same time. This will ensure that the levels of chlorothiazide in your body remain constant, helping the medicine to work more effectively.

Try not to take the medication too close to your usual bedtime, as you may find that you need to wake up in order to urinate. It is recommended that you take your last dose of chlorothiazide at least four hours before your usual bedtime.

If you are also taking cholestyramine or colestipol, you should be aware that these drugs can prevent the full absorption of chlorothiazide, meaning that you may not get the full benefit of your treatment with the drug. To avoid this issue, you should take your dose of cholestyramine or colestipol at least four hours after or before you take your prescribed dose of chlorothiazide.

For the treatment of edema (suspension):

• Adults: 10 to 20 ml once or twice daily, or as directed by your doctor.
• Children: Use and dose rate is based on body weight and must be taken as instructed by your doctor.

For the treatment of edema (tablets):

• Adults: 500 to 1000 mg once or twice daily, or as directed by your doctor.
• Children: Use and dose rate is based on body weight and must be taken as instructed by your doctor.

For the treatment of hypertension (suspension):

• Adults: 10 to 20 ml once daily, or as directed by your doctor. Dose may be divided.
• Children: Use and dose rate is based on body weight and must be taken as instructed by your doctor.

For the treatment of hypertension (tablets):

• Adults: 500 to 1000 mg once daily, or as directed by your doctor. Dose may be divided.
• Children: Use and dose rate is based on body weight and must be taken as instructed by your doctor.

In the event that you miss a dose of your medicine, you should try to take the missed dose as soon as you can. However, if it is nearly time for the next scheduled dose, do not take double the amount. Instead, just revert to your usual schedule.

If you overdose and serious side effects occur, such as loss of consciousness or development of severe breathing difficulties, you should call 911 immediately.

Drug interactions

There are some drugs that should not be used at the same time, as interactions may occur. However, in some cases it may be appropriate to use a combination of different drugs, even though an interaction is likely to take place. In cases such as this, your doctor may change the dose of one or more of your drugs or propose other ways in which the effects of the interactions can be managed or prevented.

Tell your doctor if you are already taking any other form of medicine. Include non-prescription medicines, herbal remedies, and vitamin supplements. Interactions can occur with some drugs if they are taken with certain foods, or with tobacco or alcohol.

It is likely that the following drugs will have an interaction with chlorothiazide so the two should not be taken together unless you are told to do so by your treating physician:

• Valdecoxib
• Tolmetin
• Tolfenamic Acid
• Tiaprofenic Acid
• Tenoxicam
• Sulindac
• Sodium Salicylate
• Salsalate
• Salicylic Acid
• Rofecoxib
• Proquazone
• Propyphenazone
• Proglumetacin
• Piroxicam
• Piketoprofen
• Phenylbutazone
• Parecoxib
• Oxyphenbutazone
• Oxaprozin
• Nimesulide Beta Cyclodextrin
• Nimesulide
• Niflumic Acid
• Nepafenac
• Naproxen
• Nabumetone
• Morniflumate
• Metildigoxin
• Meloxicam
• Mefenamic Acid
• Meclofenamate
• Lumiracoxib
• Loxoprofen
• Lornoxicam
• Lithium
• Ketorolac
• Ketoprofen
• Ketanserin
• Indomethacin
• Ibuprofen
• Flurbiprofen
• Flufenamic Acid
• Floctafenine
• Flecainide
• Feprazone
• Fepradinol
• Fenoprofen
• Felbinac
• Etoricoxib
• Etofenamate
• Etodolac
• Droxicam
• Dofetilide
• Dipyrone
• Digoxin
• Digitoxin
• Digitalis
• Diflunisal
• Diclofenac
• Dexketoprofen
• Dexibuprofen
• Deslanoside
• Clonixin
• Choline Salicylate
• Celecoxib
• Bufexamac
• Bromfenac
• Bepridil
• Aspirin
• Arsenic Trioxide
• Amtolmetin Guacil
• Amphetamine
• Acetyldigoxin
• Acemetacin
• Aceclofenac

Although there are no recorded drug interactions between chlorothiazide and the following products, an increase risk of side effects may occur when the two are used together:

• calcium
• ginkgo
• gossypol
• licorice


In addition to prescribing a course of chlorothiazide to treat your condition, your GP may also suggest other lifestyle changes, including weight loss, and dietary changes to reduce the amount of salt and potassium in your diet. However, you should not suddenly change your diet without first talking with your doctor.

Once you begin taking chlorothiazide, it is likely that you will feel normal and that any previous symptoms of high blood pressure will disappear. Do not stop taking your medication, even though you might feel fine. You must also attend regular check-up appointments and undergo any test that your doctor feels are appropriate. You should also be aware that you might need to take chlorothiazide for the rest of your life, in order to control your condition.

If you are pregnant or likely to become pregnant, you should tell your doctor before you begin taking this medication.

Chlorothiazide can change the composition or production of breast milk, which could affect nursing infants. Tell your doctor if you are breastfeeding, and ask your midwife for advice on alternatives for the duration of your treatment.

Some medical conditions or a history of them can impact on the efficacy of this drug. Be sure to tell your medical team if you have any other health conditions, especially:

• anuria

Chlorothiazide must NOT be used in patients who have this condition.

Chlorothiazide must be used with caution in patients who have a history of the following conditions, as studies have shown that it can make these problems worse:

• systemic lupus erythematosus
• low blood sodium levels
• low blood potassium levels
• low blood magnesium levels
• low blood chloride levels
• liver disease
• high cholesterol
• high blood levels of uric acid
• high blood calcium
• gout
• diabetes
• asthma

Chlorothiazide should be used with caution in patients who have a history of kidney problems, as this drug may be removed from the body more slowly, potentially affecting dosage levels and presenting a risk of overdose.

Some people report feeling dizzy or having blurred vision when they are taking chlorothiazide. If you find that you are affected in this way, you should not use heavy machinery, drive, or perform any potentially dangerous activity. Avoid or limit your consumption of alcohol.

Chlorothiazide can cause severe sweating, vomiting, and diarrhea, which can lead to dehydration. If you are suffering any of these problems, you must mention them to your doctor immediately. In order to avoid dehydration, drink lots of fresh water, unless your doctor tells you not to.

Chlorothiazide can decrease the levels of potassium in your body. Use a potassium supplement as recommended by your doctor, or eat potassium-rich foods such as bananas and fresh orange juice.

Chlorothiazide can make you more sensitive to the effects of the sun. If possible, limit the amount of time that you spend outdoors and do not use sunlamps or tanning booths. When venturing out into the sun, use a good-quality sunblock, and be sure to wear a hat, long trousers, and a long-sleeved shirt. If you do get sunburned, tell your doctor immediately.


  • Always keep your supply of chlorothiazide in an airtight container and at room temperature.
  • Do not freeze or refrigerate this medication.
  • Do not place your supply of chlorothiazide in a place where it will be exposed to direct sunlight, heat sources, and moisture.
  • Keep all medication out of reach of pets and small children. In the event that a pet consumes chlorothiazide, you must talk to your vet immediately for guidance.
  • Do not use any chlorothiazide that has passed its use-by date. Do not take any medicine where the packaging is damaged or appears to have been opened; ask your doctor for a fresh prescription.

Your pharmacist will give you advice on the safest method of disposal for any unwanted or out-of-date medication. Do not flush the chlorothiazide solution or tablets down the toilet or put it down the drain. Never throw out unwanted medicines with your trash where it could be found and consumed by children or animals.


Chlorothiazide is a thiazide diuretic drug (‘water pill’). It is widely used alone or with other drugs in the treatment of patients who have water retention problems caused by certain illnesses. The drug is also used to treat people whose blood pressure is too high. Although chlorothiazide cannot cure any of the conditions it is used to treat, it does provide an effective means of controlling and preventing the side effects that these health problems can cause.

In the US, chlorothiazide is known by its brand name, Diuril. It is a prescription drug that is obtainable only from a medical professional, and it is given as a suspension or tablet.

There is a wide range of drugs and non-prescription medicines that should not be used with chlorothiazide. In addition, there are many common health conditions that should not be treated with this drug, as it can exacerbate the side effects they cause, or can even make the conditions themselves worse. It is therefore very important that you discuss your medical history and your current drug regimen fully with your treating physician, before you start on a course of treatment with chlorothiazide.

It is important to realise that chlorothiazide cannot cure your medical condition. However, it is very beneficial to patients who have problems regulating their blood pressure, when taken as directed by a doctor. In order to get the most benefit from your treatment with this drug, you must attend your doctor for regular check-ups and progress reports. You will also need to undergo regular blood and blood pressure checks to make sure that the treatment is working properly and that you are not experiencing any unwanted side effects.