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Generic Name:

chlorthalidone-clonidine, Oral tablet

All Brands

  • Clorpres
  • Combipres (Discontinued)
A discontinued drug is a drug that has been taken off the market due to safety issues, shortage of raw materials, or low market demand.
SECTION 1 of 4

Highlights for chlorthalidone-clonidine

Oral tablet
1

Chlorthalidone/clonidine is a combination of two drugs in a single form that work in different ways to treat high blood pressure (hypertension).

2

The starting dose is 15 mg chlorthalidone/0.1 mg clonidine taken by mouth 1–2 times per day. Your doctor may increase your dose depending on how you respond to this drug.

3

You shouldn’t stop taking chlorthalidone/clonidine without talking to your doctor. Suddenly stopping this drug can cause unpleasant side effects, such as nervousness, agitation, and headache. If you need to stop taking it, your doctor will slowly reduce your dose.

4

Common side effects include tiredness, dizziness, constipation, and dry mouth.

IMPORTANT INFORMATION

Liver or kidney disease

Use this drug with caution if you have liver or kidney disease. This drug may make your condition worse.

Sensitivity reaction

If you have a history of allergy or asthma, you may have a reaction that makes it harder to breathe to this drug.

Surgery

Let your doctor know that you’re taking this drug before you have any type of surgery. Your doctor should have you stop taking this drug within 4 hours of your surgery. After the surgery, you can start taking it again.

What is chlorthalidone/clonidine?

This drug is a prescription drug. It’s available as an oral tablet.

This drug is available as a brand-name drug called Clorpres. It’s not available as a generic drug.

This drug is a combination product. It contains two medications in a single tablet. If you’re taking both of these drugs separately, taking them as a combination in a single tablet makes it more convenient for you.

This drug may be taken in combination with other drugs to treat high blood pressure.

Why it's used

This drug is used to treat high blood pressure (hypertension).

How it works

Chlorthalidone belongs to a class of drugs called diuretics. Clonidine belongs to a class of drugs called alpha receptor agonists.

See Details

How it works

Chlorthalidone belongs to a class of drugs called diuretics. Clonidine belongs to a class of drugs called alpha receptor agonists. A class of drugs refers to medications that work similarly. They have a similar chemical structure and are often used to treat similar conditions.

Chlorthalidone makes your body get rid of extra water and salt through the urine. This results in lower blood pressure.

Clonidine relaxes your blood vessels by reducing your nervous system activity.

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SECTION 2 of 4

chlorthalidone-clonidine Side Effects

Oral tablet

Most Common Side Effects

The most common side effects that occur with chlorthalidone/clonidine include:

  • fatigue

  • dizziness

  • constipation

  • drowsiness

If these effects are mild, they may go away within a few days or a couple of weeks. If they’re more severe or don’t go away, talk to your doctor or pharmacist.

Serious Side Effects

If you experience any of these serious side effects, call your doctor right away. If your symptoms are potentially life-threatening, or if you think you’re experiencing a medical emergency, call 9-1-1.

  • damage to your retina of your eye. This may not always cause any symptoms, so it’s important to have your eyes checked regularly. Symptoms include:

    • blurred vision
    • dry eyes
    • burning of your eyes
  • changes to your body’s electrolyte levels. Symptoms include:

    • dry mouth
    • thirst
    • weakness
    • loss of energy
    • drowsiness
    • restlessness
    • muscle pain, cramps, or tiredness
    • not producing as much urine as normal
    • feeling like your heart is pounding (palpitations)
    • nausea or vomiting
  • high blood sugar (hyperglycemia). Symptoms include:

    • intense thirst
    • urinating more often than normal
Pharmacist's Advice
Clinical Associate Professor, University of Illinois at Chicago College of Pharmacy

This drug may cause drowsiness. You shouldn’t drive, use machinery, or do other tasks that require alertness until you know how this drug affects you.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this information includes all possible side effects. This information is not a substitute for medical advice. Always discuss possible side effects with a healthcare provider who knows your medical history.
SECTION 3 of 4

chlorthalidone-clonidine May Interact with Other Medications

Oral tablet

Chlorthalidone/clonidine can interact with other medications, herbs, or vitamins you might be taking. That’s why your doctor should manage all of your medications carefully. If you’re curious about how this drug might interact with something else you’re taking, talk to your doctor or pharmacist.

Note: You can reduce your chances of drug interactions by having all of your prescriptions filled at the same pharmacy. That way, a pharmacist can check for possible drug interactions.

Alcohol interaction

The use of drinks that contain alcohol can increase your risk of dizziness and drowsiness from chlorthalidone/clonidine. You may have slowed reflexes, poor judgment, and sleepiness. This can be dangerous. If you drink alcohol, talk to your doctor.

Medications that might interact with this drug

Depression drugs

Taking this drug with tricyclic antidepressants may increase your blood pressure. Your doctor may give you a higher dose of clonidine to manage your blood pressure.

These drugs include:

  • amitriptyline
  • desipramine
  • doxepin (topical)
  • imipramine
  • nortriptyline
  • protriptyline
  • trimipramine

Barbiturates and other sedating drugs

Taking clonidine with barbiturates or other drugs that cause sedation may increase your risk of sedation.

These drugs include:

  • barbiturates, such as:
    • amobarbital
    • butabarbital
    • butalbital
    • methohexital
    • pentobarbital
    • phenobarbital
    • secobarbital
    • thiopental
  • sedating drugs, such as:
    • alprazolam
    • amoxapine
    • aripiprazole
    • asensapine
    • azelastine
    • baclofen
    • bromazepam
    • buprenorphine
    • buspirone
    • butabarbital
    • carbamazepine
    • carisoprodol
    • cetirizine
    • chlorpheniramine
    • chlorpromazine
    • clobazam
    • clonazepam
    • clonidine
    • clozapine
    • codeine
    • cyclobenzaprine
    • dantrolene
    • desloratadine
    • diazepam
    • diphenhydramine
    • droperidol
    • ebastine
    • efavirenz
    • fentanyl
    • fexofenadine
    • flibanserin
    • gabapentin
    • guanfacine
    • haloperidol
    • hydromorphone
    • levetiracetam
    • loratadine
    • lorazepam
    • meperidine
    • methadone
    • midazolam
    • morphine
    • nortriptyline
    • olanzapine
    • oxazepam
    • oxycodone
    • oxymorphone
    • pentobarbital
    • phenobarbital
    • pregabalin
    • propofol
    • quetiapine
    • ramelteon
    • risperidone
    • scopolamine
    • tempazepam
    • topiramate
    • tramadol
    • ziprasidone

Digoxin

Taking these drugs together may change the amount of potassium in your body and cause irregular heart rate.

High blood pressure drugs

Taking other drugs to treat high blood pressure with medicine may cause dangerously low blood pressure levels. You may need to monitor your blood pressure more closely.

These drugs include:

  • angiotensin-converting enzyme (ACE) inhibitors, such as:  
    • benazepril
    • captopril
    • clizapril
    • enalapril
    • enalaprilat
    • fosniopril
    • imidapril
    • moexipril
    • perindopril
    • qunapril
    • ramipril
    • trandolapril
  • angiotensin receptor blockers (ARBs), such as:
    • irbesartan
    • losartan
    • olmesartan
    • telmisatan
    • valsartan
  • beta blockers, such as:
    • acebutolol
    • arotinolol
    • atenolol
    • betaxolol
    • bisoprolol
    • esmolol
    • metoprolol
    • nadolol
    • nebivolol
    • penbutolol
    • pindolol
    • propranolol
    • timolol (systemic)
  • calcium channel blockers, such as:
    • amlodipine
    • felodipine
    • nicardipine
    • nifedipine
  • loop diuretics, such as:
    • bumetanide
    • furosemide
    • indapamide
    • torsemide
  • potassium-sparing diuretics, such as:
    • eplerenone
    • spironolactone
    • triamterene
  • thiazide diuretics, such as:
    • chlorthiazide
    • chlorthalidone
    • hydrochlorothiazide
    • methylclothiazide
    • metolazone

Diabetes drugs

Drugs used to treat diabetes may not work as well when taken with chlorthalidone/clonidine. This could cause higher blood sugar levels. Your doctor may change the dose of your diabetes medicines.

These drugs include:

  • amylin analogs, such as:
    • pramlintide
  • biguanides, such as:
    • metformin
  • GLP-1 agonists, such as:
    • exenatide
    • liraglutide
    • lixisentaide
  • DPP4 inhibitors, such as:
    • saxagliptin
    • sitagliptin
  • insulin, such as:
    • insulin aspart
    • insulin detemir
    • insulin glargine
    • insulin glulisine
    • insulin lispro
    • insulin NPH
    • insulin regular
  • meglitinides, such as:
    • nateglinide
    • repaglinide
  • sulfonylureas, such as:
    • glimepriide
    • glipizide
    • glyburide
  • SGLT-2 inhibitors, such as:
    • canagliflozin
    • dapagliflozin
    • empagliflozin
  • thiazolidinediones, such as:
    • pioglitazone
    • rosiglitazone

Lithium

This drug may make lithium stay in your body longer. This may increase your risk of toxic effects of lithium. Your doctor may give you a lower dose.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs interact differently in each person, we cannot guarantee that this information includes all possible interactions. This information is not a substitute for medical advice. Always speak with your healthcare provider about possible interactions with all prescription drugs, vitamins, herbs and supplements, and over-the-counter drugs that you are taking.
Drug warnings
kidney disease
People with kidney disease

Use this drug with caution if you have kidney disease. This drug can harm your kidneys.

liver disease
People with liver disease

This drug can cause changes in your fluid and electrolyte levels. This can be harmful in people with liver disease. Use this drug with caution.

asthma
People with asthma

People with a history of allergy or asthma may have a reaction to this drug that makes it harder to breathe.

heart disease or stroke
People with a history of heart disease or stroke

Use this drug with caution if you have a history of heart disease, heart attack, or stroke. This medication can change your heart rate and make it harder for your heart to work.

pregnant women
Pregnant women

Chlorthalidone is a pregnancy category B drug. That means two things:

  1. Research in animals has not shown a risk to the fetus when the mother takes the drug.
  2. There aren’t enough studies done in humans to show if the drug poses a risk to the fetus.

Talk to your doctor if you’re pregnant or planning to become pregnant. Animal studies do not always predict the way humans would respond. Therefore, this drug should only be used in pregnancy if clearly needed.

Clonidine is a category C pregnancy drug. That means two things:

  1. Research in animals has shown adverse effects to the fetus when the mother takes the drug.
  2. There haven’t been enough studies done in humans to be certain how the drug might affect the fetus.

Talk to your doctor if you’re pregnant or planning to become pregnant. This drug should only be used if the potential benefit justifies the potential risk to the fetus.

breastfeeding
Women who are breast-feeding

This drug may pass into breast milk and may cause side effects in a child who is breast-fed.

Talk to your doctor if you breast-feed your baby. You may need to decide whether to stop breast-feeding or stop taking this medication.

for seniors
For seniors

Older adults may process drugs more slowly. A normal adult dose may cause levels of this drug to be higher than normal in your body. If you’re a senior, you may need a lower dose or a different schedule.

for children
For children

This medicine hasn’t been studied in children and shouldn’t be used in children younger than 18 years.

call doctor
When to call the doctor

Call your doctor if your blood pressure is too high or too low. Your doctor will give you guidelines for what blood pressure readings are considered too high or too low.

allergies
Allergies

This drug can cause a severe allergic reaction. Symptoms include:

  • trouble breathing
  • swelling of your throat or tongue
  • hives

Call 9-1-1 or go to the nearest emergency room if you develop these symptoms.

Don’t take this drug again if you’ve ever had an allergic reaction to it or other sulfonamide drugs before. Taking it again could be fatal (cause death).

SECTION 4 of 4

How to Take chlorthalidone-clonidine (Dosage)

Oral tablet

All possible dosages and forms may not be included here. Your dose, form, and how often you take it will depend on:

  • your age
  • the condition being treated
  • how severe your condition is
  • other medical conditions you have
  • how you react to the first dose

What are you taking this medication for?

High blood pressure (hypertension)

Brand: Clorpres

Form: Oral tablet
Strengths:
  • 15 mg chlorthalidone/0.1 mg clonidine
  • 15 mg chlorthalidone/0.2 mg clonidine
  • 15 mg chlorthalidone/0.3 mg clonidine
Adult dosage (ages 18–64 years)

The starting dose is 15 mg chlorthalidone/0.1 clonidine taken by mouth 1–2 times per day. The maximum dose is 30 mg chlorthalidone/0.6 mg clonidine per day.

Child dosage (ages 0–17 years)

This medicine hasn’t been studied in children and shouldn’t be used in children younger than 18 years.

Senior dosage (ages 65 years and older)

There are no specific recommendations for senior dosing. Older adults may process drugs more slowly. A normal adult dose may cause levels of this drug to be higher than normal. If you’re a senior, you may need a lower dose or a different schedule.

Disclaimer: Our goal is to provide you with the most relevant and current information. However, because drugs affect each person differently, we cannot guarantee that this list includes all possible dosages. This information is not a substitute for medical advice. Always to speak with your doctor or pharmacist about dosages that are right for you.
Pharmacist's Advice
Clinical Associate Professor, University of Illinois at Chicago College of Pharmacy

This drug comes with serious risks if you don't take it as prescribed.

If you don’t take it at all

Your blood pressure may get worse. This may raise your risk of a heart attack or stroke.

If you stop taking it suddenly

Don’t stop taking this drug without talking to your doctor. Suddenly stopping this drug can cause unpleasant withdrawal effects such as nervousness, agitation, and headache. High blood pressure can also occur during withdrawal. This may increase your chance for a heart attack or stroke.

If you don’t take it on schedule

Your blood pressure may not improve or may get worse. You may have a higher chance of a heart attack or stroke.

What to do if you miss a dose

If you forget to take your dose, take it as soon as you remember. If it’s just a few hours until the time for your next dose, then wait and only take one dose at that time.

Never try to catch up by taking two doses at once. This could cause toxic side effects.

If you take too much

Taking too much this drug can cause your blood pressure to drop very low. It may also increase your risk of side effects, including:

  • fatigue
  • dizziness
  • drowsiness

If you think you’ve taken too much of the drug, act right away. Call your doctor or local Poison Control Center, or go to the nearest emergency room.

How to tell this drug is working

You may be able tell if this drug is working if your blood pressure is lower. You may also notice that you need to urinate more.

This drug is a long-term treatment.

Important considerations for taking this drug

Store this drug at room temperature

  • Keep it from 68°F (20°C) to 77°F (25°C).
  • Don’t freeze this drug.
  • Keep it away from light.
  • Keep it away from high temperature.
  • Keep your drugs away from areas where they could get wet, such as bathrooms. Store this drug away from moisture and damp locations.

Travel

When traveling with your medication:

  • Always carry it with you or in your carry-on bag.
  • Don’t worry about airport x-ray machines. They can’t hurt this medication.
  • You may need to show airport staff your pharmacy’s label to clearly identify the medication. Keep the original prescription label with you when traveling.
  • Don’t leave this medicine in the car, especially when the temperature is hot or freezing.

Self-management

You may need to check your blood pressure at home. Your doctor may show you how to do this. You should keep a log with the date, time of day, and your blood pressure readings. Bring this diary with you to your doctor appointments.

You may also need to buy your own blood pressure monitoring machine. These are available at most pharmacies.

Clinical monitoring

Your doctor may check your body’s electrolyte levels through a blood test while you’re taking this drug.

Hidden costs

You may need to purchase a blood pressure monitor to check your blood pressure at home.

Insurance

Many insurance companies require a prior authorization for this drug. This means your doctor will need to get approval from your insurance company before your insurance company will pay for the prescription.

Are there any alternatives?

There are other drugs available to treat your condition. Some may be more suitable for you than others. Talk to your doctor about possible alternatives.


Show Sources

Content developed in collaboration with University of Illinois-Chicago, Drug Information Group

Medically reviewed by Creighton University, Center for Drug Information and Evidence-Based Practice on September 10, 2015

Disclaimer: Healthline has made every effort to make certain that all information is factually correct, comprehensive, and up-to-date. However, this article should not be used as a substitute for the knowledge and expertise of a licensed healthcare professional. You should always consult your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or adverse effects. The absence of warnings or other information for a given drug does not indicate that the drug or drug combination is safe, effective, or appropriate for all patients or all specific uses.
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