Medically reviewed by Drugs.com. Last updated on Jun 28, 2022.
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
Therapeutic Class: Alpha-Adrenergic Agonist/Thiazide Combination
Pharmacologic Class: Clonidine
Chemical Class: Thiazide Related
Uses for Clorpres
Clonidine and chlorthalidone combinations are used in the treatment of high blood pressure (hypertension).
High blood pressure adds to the work load of the heart and arteries. If it continues for a long time, the heart and arteries may not function properly. This can damage the blood vessels of the brain, heart, and kidneys resulting in a stroke, heart failure, or kidney failure. Hypertension may also increase the risk of heart attacks. These problems may be less likely to occur if blood pressure is controlled.
Clonidine works by controlling nerve impulses along certain body nerve pathways. As a result, it relaxes blood vessels so that blood passes through them more easily. The chlorthalidone in this combination is a diuretic (water pill) that helps reduce the amount of water in the body by increasing the flow of urine.
Clonidine and chlorthalidone combination is available only with your doctor's prescription.
Before using Clorpres
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Studies on this medicine have been done only in adult patients, and there is no specific information comparing use of clonidine and chlorthalidone combination in children with use in other age groups. However, children may be more sensitive than adults to clonidine. Clonidine overdose has been reported when children accidentally took this medicine.
Dizziness or lightheadedness and signs of too much potassium loss may be more likely to occur in the elderly, who are more sensitive to the effects of clonidine and chlorthalidone.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.
Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Amtolmetin Guacil
- Arsenic Trioxide
- Choline Salicylate
- Flufenamic Acid
- Iobenguane I 131
- Mefenamic Acid
- Niflumic Acid
- Nimesulide Beta Cyclodextrin
- Salicylic Acid
- Sodium Salicylate
- Tiaprofenic Acid
- Tolfenamic Acid
Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.
- Aminolevulinic Acid
Interactions with food/tobacco/alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.
Other medical problems
The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:
- Type 2 diabetes mellitus—This medicine may change the amount of diabetes medicine needed
- Gout—This medicine may increase the amount of uric acid in the blood, which can lead to gout
- Heart or blood vessel disease or
- Lupus erythematosus (history of) or
- Mental depression (history of) or
- Pancreatitis (inflammation of the pancreas) or
- Raynaud's syndrome—This medicine may make these conditions worse
- Kidney disease—Effects of this medicine may be increased because of slower removal from the body. If kidney disease is severe, the chlorthalidone portion of this medicine may not work
- Liver disease—If this medicine causes loss of too much water from the body, liver disease can become much worse
Proper use of Clorpres
This medicine may cause you to have an unusual feeling of tiredness when you begin to take it. You may also notice an increase in the amount of urine or in your frequency of urination. After taking the medicine for a while, these effects should lessen. It is best to plan your doses according to a schedule that will least affect your personal activities and sleep. Ask your health care professional to help you plan the best time to take this medicine.
In addition to the use of the medicine your doctor has prescribed, appropriate treatment for your high blood pressure may include weight control and care in the types of foods you eat, especially foods high in sodium. Your doctor will tell you which factors are most important for you. You should check with your doctor before changing your diet.
Many patients who have high blood pressure will not notice any signs of the problem. In fact, many may feel normal. It is very important that you take your medicine exactly as directed and that you keep your appointments with your doctor even if you feel well.
Remember that this medicine will not cure your high blood pressure but it does help control it. Therefore, you must continue to take it as directed if you expect to lower your blood pressure and keep it down. You may have to take high blood pressure medicine for the rest of your life . If high blood pressure is not treated, it can cause serious problems such as heart failure, blood vessel disease, stroke, or kidney disease.
To help you remember to take your medicine, try to get into the habit of taking it at the same time each day.
The dose of this medicine will be different for different patients. Follow your doctor's orders or the directions on the label. The following information includes only the average doses of this medicine. If your dose is different, do not change it unless your doctor tells you to do so.
The amount of medicine that you take depends on the strength of the medicine. Also, the number of doses you take each day, the time allowed between doses, and the length of time you take the medicine depend on the medical problem for which you are using the medicine.
- For oral dosage form (tablets):
- For high blood pressure:
- Adults—1 tablet one or two times a day.
- Children—Use and dose must be determined by your doctor.
- For high blood pressure:
If you miss a dose of this medicine, take it as soon as possible. However, if it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not double doses.
If you miss two or more doses in a row, check with your doctor right away. If your body goes without this medicine for too long, your blood pressure may go up to a dangerously high level and some unpleasant effects may occur.
Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. Keep from freezing.
Keep out of the reach of children.
Do not keep outdated medicine or medicine no longer needed.
Precautions while using Clorpres
It is important that your doctor check your progress at regular visits to make sure that this medicine is working properly.
Check with your doctor before you stop taking this medicine. Your doctor may want you to reduce gradually the amount you are taking before stopping the medicine completely.
Make sure that you have enough medicine on hand to last through weekends, holidays, or vacations. You should not miss taking any doses. You may want to ask your doctor for another written prescription to carry in your wallet or purse. You can then have it filled if you run out of medicine when you are away from home.
Before having any kind of surgery (including dental surgery) or emergency treatment, make sure the medical doctor or dentist in charge knows that you are taking this medicine.
Do not take other medicines unless they have been discussed with your doctor. This especially includes over-the-counter (nonprescription) medicines for appetite control, asthma, colds, cough, hay fever, or sinus problems, since they may tend to increase your blood pressure.
This medicine will add to the effects of alcohol and other central nervous system (CNS) depressants (medicines that slow down the nervous system, possibly causing drowsiness). Some examples of CNS depressants are antihistamines or medicine for hay fever, other allergies, or colds; sedatives, tranquilizers, or sleeping medicine; prescription pain medicine or narcotics; barbiturates; medicine for seizures; muscle relaxants; or anesthetics, including some dental anesthetics. Check with your doctor before taking any of the above while you are using this medicine.
This medicine may cause some people to become drowsy or less alert than they are normally. This is more likely to happen when you begin to take it or when you increase the amount of medicine you are taking. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are not alert.
Dizziness, lightheadedness, or fainting may occur, especially when you get up from a lying or sitting position. Getting up slowly may help, but if the problem continues or gets worse, check with your doctor.
The dizziness, lightheadedness, or fainting is also more likely to occur if you drink alcohol, stand for long periods of time, exercise, or if the weather is hot. Drinking alcoholic beverages may also make the drowsiness worse. While you are taking this medicine, be careful to limit the amount of alcohol you drink. Also, use extra care during exercise or hot weather or if you must stand for long periods of time.
This medicine may cause a loss of potassium from your body.
- To help prevent this, your doctor may want you to:
- eat or drink foods that have a high potassium content (for example, orange or other citrus fruit juices), or
- take a potassium supplement, or
- take another medicine to help prevent the loss of the potassium in the first place.
- It is very important to follow these directions. Also, it is important not to change your diet on your own. This is more important if you are already on a special diet (as for diabetes), or if you are taking a potassium supplement or a medicine to reduce potassium loss. Extra potassium may not be necessary and, in some cases, too much potassium could be harmful.
Check with your doctor if you become sick and have severe or continuing vomiting or diarrhea. These problems may cause you to lose additional water and potassium.
For patients with diabetes:
- The chlorthalidone contained in this medicine may raise blood sugar levels. While you are using this medicine, be sure to test your blood sugar (glucose) level, or test for sugar in your urine.
This medicine may cause your skin to be more sensitive to sunlight than it is normally. Exposure to sunlight, even for brief periods of time, may cause a skin rash, itching, redness or other discoloration of the skin, or a severe sunburn. When you begin taking this medicine:
- Stay out of direct sunlight, especially between the hours of 10:00 a.m. and 3:00 p.m., if possible.
- Wear protective clothing, including a hat. Also, wear sunglasses.
- Apply a sun block product that has a skin protection factor (SPF) of at least 15. Some patients may require a product with a higher SPF number, especially if they have a fair complexion. If you have any questions about this, check with your health care professional.
- Apply a sun block for lips that has an SPF of at least 15 to protect your lips.
- Do not use a sunlamp or tanning bed or booth.
If you have a severe reaction from the sun, check with your doctor.
This medicine may cause dryness of the mouth. For temporary relief, use sugarless candy or gum, melt bits of ice in your mouth, or use a saliva substitute. However, if your mouth continues to feel dry for more than 2 weeks, check with your medical doctor or dentist. Continuing dryness of the mouth may increase the chance of dental disease, including tooth decay, gum disease, and fungus infections.
Clorpres side effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor immediately if any of the following side effects occur:
Signs and symptoms of overdose
- Difficulty in breathing
- dizziness (extreme) or faintness
- feeling cold
- pinpoint pupils of eyes
- slow heartbeat
- unusual tiredness or weakness (extreme)
Check with your doctor as soon as possible if any of the following side effects occur:
Signs and symptoms of too much potassium loss
- Dryness of mouth
- increased thirst
- irregular heartbeat
- mood or mental changes
- muscle cramps or pain
- nausea or vomiting
- weak pulse
Signs and symptoms of too much sodium loss
- convulsions (seizures)
- decreased mental activity
- muscle cramps
- unusual tiredness or weakness
- Mental depression
- swelling of feet and lower legs
- Black, tarry stools
- blood in urine or stools
- cough or hoarseness
- fever or chills
- joint pain
- lower back or side pain
- paleness or cold feeling in fingertips and toes
- pinpoint red spots on skin
- skin rash or hives
- stomach pain (severe) with nausea and vomiting
- unusual bleeding or bruising
- vivid dreams or nightmares
- yellow eyes or skin
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
- dryness of mouth
- unusual tiredness or weakness
- Decreased sexual ability
- dizziness or lightheadedness when getting up from a lying or sitting position
- dry, itching, or burning eyes
- increased sensitivity of skin to sunlight
- loss of appetite
- nausea or vomiting
- upset stomach
After you stop using this medicine, it may still produce some side effects that need attention. During this period of time, check with your doctor immediately if you notice the following side effects:
- Anxiety or tenseness
- chest pain
- fast or pounding heartbeat
- increased salivation
- shaking or trembling of hands and fingers
- stomach cramps
- trouble in sleeping
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
More about Clorpres (chlorthalidone / clonidine)
- Side effects
- Drug interactions
- Dosage information
- During pregnancy
- Drug images
- Drug class: antiadrenergic agents (central) with thiazides
Related treatment guides
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.