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Clonidine/Chlorthalidone, Oral KLON-i-deen klor-THAL-i-done

What are other names for this medicine?

Type of medicine: antihypertensive/diuretic

Generic and brand names: clonidine and chlorthalidone, oral; Clorpres

What is this medicine used for?

This medicine is taken by mouth to treat high blood pressure.

It may be used for other conditions as determined by your healthcare provider.

What should my healthcare provider know before I take this medicine?

Before taking this medicine, tell your healthcare provider if you have ever had:

  • an allergic reaction to any medicine
  • asthma
  • a stroke
  • depression
  • diabetes
  • heart disease or a recent heart attack
  • kidney disease or liver disease.
  • gout
  • too much or too little sodium, potassium, magnesium, or calcium in the blood
  • lupus

Females of childbearing age: Tell your healthcare provider if you are pregnant or plan to become pregnant. It is not known whether this medicine will harm an unborn baby. Do not breast-feed while taking this medicine without with your healthcare provider's approval.

How do I take it?

Check the label on the medicine for directions about your specific dose. Take this medicine exactly as your healthcare provider prescribes. Take it regularly, even if you feel better. Do not stop taking this medicine without your healthcare provider's approval. You may have to gradually reduce your dosage.

This medicine increases urination. Take the last dose of the day before 6 PM to avoid interrupting your sleep at night. Take this medicine with food.

What if I miss a dose?

Do not miss doses. If you miss a dose, take it as soon as you remember unless it is almost time for the next scheduled dose. In that case, skip the missed dose and take the next one as directed. Do not take double doses. If you are not sure of what to do if you miss a dose, or if you miss more than one dose, contact your healthcare provider.

What if I overdose?

If you or anyone else has intentionally taken too much of this medicine, call 911 or go to the emergency room right away. If you pass out, have seizures, weakness or confusion, or have trouble breathing, call 911. If you think that you or anyone else may have taken too much of this medicine, call the poison control center. Do this even if there are no signs of discomfort or poisoning. The poison control center number is 800-222-1222.

Symptoms of an acute overdose may include: drowsiness, irritability; tiredness, weakness, lightheadedness, slow heartbeat, nausea, vomiting, increased urination, shallow breathing, pinpoint pupils, seizures.

What should I watch out for?

Your provider may want you to have your blood pressure checked regularly. You will need to have blood tests regularly to see how this medicine affects you. Keep all appointments. If you develop extreme nervousness, shakiness, headache, or increased blood pressure after you stop taking this medicine, contact your healthcare provider immediately.

This medicine may make your mouth dry. Keep it moist with liquids, ice, or sugar-free hard candy. If dry mouth becomes a problem, ask your healthcare provider what to do.

Follow a low-salt diet if your healthcare provider prescribes one to help lower your blood pressure.

If you need emergency care, surgery, or dental work, tell the healthcare provider or dentist you are taking this medicine.

This medicine increases the effects of alcohol and other drugs that slow down your nervous system. Do not drink alcohol or take other medicines unless your healthcare provider approves.

You may feel faint when you get up quickly after sitting or lying down. Getting up slowly may lessen this reaction.

This medicine may make you drowsy or dizzy. Do not drive or operate machinery unless you are fully alert.

This medicine may drive potassium (a vital mineral) from your body. Your healthcare provider may prescribe a potassium-rich diet or a potassium supplement for you to take every day.

This medicine may make your skin more sensitive to the sun, which may lead to painful sunburns. While you are taking this medicine, avoid long exposure to the sun. Wear protective clothing, a hat, and sunscreen lotion when you need to be outdoors. Do not use a sunlamp. If you get a severe sunburn, contact your healthcare provider right away.

This medicine may increase the risk of dehydration. Contact your healthcare provider if you develop severe vomiting or diarrhea while you are taking this medicine. Be careful when exercising, especially in hot weather.

Diabetics: This medicine may affect your blood sugar level and change the amount of insulin or other diabetes medicines you may need. Talk to your healthcare provider about this.

What are the possible side effects?

Along with its needed effects, your medicine may cause some unwanted side effects. Some side effects may be very serious. Some side effects may go away as your body adjusts to the medicine. Tell your healthcare provider if you have any side effects that continue or get worse.

Life-threatening (Report these to your healthcare provider right away. If you cannot reach your healthcare provider right away, get emergency medical care or call 911 for help): Allergic reaction (hives; itching; rash; trouble breathing; tightness in your chest; swelling of your lips, tongue, and throat).

Serious (report these to your healthcare provider right away): Extreme dizziness or weakness; chest pain; increased thirst; muscle cramps or pain; irregular or fast heartbeat; confusion; restlessness; seizures; problems urinating; fainting; swelling in hands, ankles, or feet.

Other: Dry mouth, drowsiness, constipation, diarrhea, nausea, vomiting, irritated eyes, stomach upset, mild rash or itching, loss of appetite, change in sexual desire or ability.

What products might interact with this medicine?

When you take this medicine with other medicines, it can change the way this or any of the other medicines work. Nonprescription medicines, vitamins, natural remedies, and certain foods may also interact. Using these products together might cause harmful side effects. Talk to your healthcare provider if you are taking:

  • ACE inhibitors such as benazepril (Lotensin), captopril, enalapril (Vasotec), fosinopril, lisinopril (Prinivil, Zestril), quinapril (Accupril), and ramipril (Altace)
  • alpha blockers such as doxazosin (Cardura), prazosin (Minipress), and terazosin (Hytrin)
  • angiotensin receptor II blockers such as candesartan (Atacand), eprosartan (Teveten), irbesartan (Avapro), losartan (Cozaar), olmesartan (Benicar), telmisartan (Micardis), and valsartan (Diovan)
  • allopurinol (Zyloprim)
  • antipsychotics such as chlorpromazine, prochlorperazine, olanzapine (Zyprexa), risperidone (Risperdal), thioridazine, trifluoperazine, and ziprasidone (Geodon)
  • barbiturates such as butabarbital (Butisol) and phenobarbital
  • benzodiazepines such as alprazolam (Xanax), clorazepate (Tranxene), chlordiazepoxide (Librium), diazepam (Valium), lorazepam (Ativan), and oxazepam
  • beta blockers such as acebutolol (Sectral), atenolol (Tenormin), carvedilol (Coreg), labetalol (Trandate), metoprolol (Lopressor, Toprol XL), nadolol (Corgard), pindolol, propranolol (Inderal), and sotalol (Betapace)
  • calcium channel blockers such as diltiazem (Cardizem, Tiazac), felodipine, isradipine (DynaCirc), nicardipine (Cardene), nifedipine (Adalat, Procardia), and verapamil (Calan, Isoptin)
  • calcium supplements such as calcium carbonate (Tums), calcium gluconate, and calcium chloride
  • cholesterol-lowering medicines such as cholestyramine (Questran) and colestipol (Colestid)
  • corticosteroids such as betamethasone (Celestone), cortisone, dexamethasone, fludrocortisone (Florinef), hydrocortisone (Cortef), methylprednisolone (Medrol), prednisolone (Orapred), prednisone, and triamcinolone (Aristospan, Kenalog)
  • cyclosporine (Gengraf, Neoral, Sandimmune)
  • digoxin (Lanoxin, Lanoxicaps, Digitek)
  • diuretics such as amiloride, amiloride/hydrochlorothiazide (Moduretic), bumetanide, chlorothiazide (Diuril), furosemide (Lasix), hydrochlorothiazide (Microzide), spironolactone (Aldactone), spironolactone/hydrochlorothiazide (Aldactazide), torsemide (Demadex), triamterene (Dyrenium), and triamterene/hydrochlorothiazide (Dyazide, Maxzide)
  • lithium (Lithobid)
  • medicines for diabetes such as acarbose (Precose), chlorpropamide, glimepiride (Amaryl), glipizide (Glucotrol), glyburide (DiaBeta, Glynase), metformin (Glucophage), miglitol (Glyset), nateglinide (Starlix), pioglitazone (Actos), repaglinide (Prandin), rosiglitazone (Avandia), and insulin
  • natural remedies such as dong quai, ephedra, ginseng, gotu kola, kava, St. John's wort, valerian, and yohimbe
  • muscle relaxants such as baclofen (Lioresal), carisoprodol (Soma), cyclobenzaprine (Flexeril), dantrolene (Dantrium), methocarbamol (Robaxin), and tizanidine (Zanaflex)
  • narcotic pain medicines such as codeine, fentanyl (Duragesic, Actiq), hydrocodone/acetaminophen (Vicodin), hydromorphone (Dilaudid), meperidine (Demerol), morphine (Kadian, MS Contin), oxycodone (OxyContin, Roxicodone), oxycodone/acetaminophen (Percocet, Tylox), and pentazocine (Talwin)
  • NSAIDs such as diclofenac (Voltaren, Cataflam), ibuprofen (Motrin, Advil), indomethacin (Indocin), ketoprofen, ketorolac (Toradol), nabumetone (Relafen), naproxen (Aleve, Anaprox, Naprelan), oxaprozin (Daypro), piroxicam (Feldene), and sulindac (Clinoril)
  • sleeping pills such as eszopiclone (Lunesta), zaleplon (Sonata), and zolpidem (Ambien)
  • tricyclic antidepressants such as amitriptyline, desipramine (Norpramin), doxepin, imipramine (Tofranil), and nortriptyline (Pamelor)

Avoid medicines that cause drowsiness. Ask your healthcare provider or pharmacist about this.

Do not drink alcohol while you are taking this medicine without your healthcare provider's approval.

If you are not sure if your medicines might interact, ask your pharmacist or healthcare provider. Keep a list of all your medicines with you. List all the prescription medicines, nonprescription medicines, supplements, natural remedies, and vitamins that you take. Be sure that you tell all healthcare providers who treat you about all the products you are taking.

How should I store this medicine?

Store this medicine at room temperature. Keep the container tightly closed. Protect it from heat, high humidity, and bright light.


This advisory includes selected information only and may not include all side effects of this medicine or interactions with other medicines. Ask your healthcare provider or pharmacist for more information or if you have any questions.

Ask your pharmacist for the best way to dispose of outdated medicine or medicine you have not used. Do not throw medicine in the trash.

Keep all medicines out of the reach of children.

Do not share medicines with other people.


Developed by RelayHealth.
Medication Advisor 2012.1 published by RelayHealth.
Last modified: 2010-12-15
Last reviewed: 2010-11-11
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
© 2012 RelayHealth and/or its affiliates. All rights reserved.
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