Clonidine and chlorthalidone (oral)

Clonidine is a central alpha agonist while chlorthalidone is a diuretic, and the two drugs are used to lower blood pressure and prevent potentially severe cardiac events and complications.


An introduction to clonidine and chlorthalidone

Clonidine and chlorthalidone treat hypertension by lowering blood pressure. The disease forces the heart and blood vessels to work extra harder, which may eventually compromise their function and effectiveness. As such, the drugs help prevent hypertension from causing damage to the vessels of the brain and heart, protecting the patient against the danger of heart attack and stroke. Likewise, the medications help reduce the risk of heart failure and kidney disease.

On top of controlling high blood pressure, clonidine and chlorthalidone are useful in the treatment of edema or fluid retention in individuals with congestive heart failure. The combined regimen also treats edema in case of cirrhosis of the liver, as well as kidney complications. Patients with a fluid retention problem from the use of steroids or estrogen may also take the medicines to address it.

Clonidine is a type of central alpha agonist, and its activity in the brain helps lower high blood pressure. Its effectiveness stems from the ability to ease blood vessel constrictions. Using this drug helps streamline blood flow through veins and arteries, boosting circulation to all body parts, including the brain and heart.

On the other hand, chlorthalidone belongs to a category of medications called diuretics. It is a “water pill” used to treat edema from a variety of causes. A patient with edema may use the drug to eliminate excess water and salt from their body systems. As the therapeutic effects of chlorthalidone gain traction, a patient may experience a surge in the volume of urine they make. The drug also plays a complementary role in relaxing blood vessels to enhance circulation.

Treated conditions

• High blood pressure (hypertension)
• Congestive heart failure edema
• Cirrhosis of the liver
• Kidney complications
• Steroids/estrogen-linked edema

Type of drug

• Clonidine: Central alpha agonist
• Chlorthalidone: Diuretic

What are the side effects of clonidine and chlorthalidone?

Clonidine and chlorthalidone is a regimen that may cause numerous unpleasant effects on a patient. However, a doctor prescribes the medication after assessing that its therapeutic value outweighs any possible side-effects. With that said, many patients experience only some, rather than all, of the potential adverse results from using clonidine and chlorthalidone. The best course of action for a patient who has started to notice any adverse effects when using the medicines is to see a doctor immediately.

However, it is imperative to note that some of the most severe unwanted effects of clonidine and chlorthalidone result from inappropriate use. Typically, the wrong prescription for dosage or overdosing can cause a patient a range of health complications that call for immediate medical intervention.

Examples of clonidine and chlorthalidone side-effects that overdosing may cause include breathing difficulty and even severe dizziness. Excessive intake of the medication may also slow the heart rate of a victim, and sometimes cause them to feel unusually exhausted or extremely weak. Likewise, it is not unheard of for an overdosed patient to complain about feeling cold or having strangely tiny eye pupils under usual lighting intensity.

In short, a patient should suspect overdose and quickly see their doctor if they experience any of the side effects below:

• Breathing difficulty
• Extreme lightheadedness (or fainting)
• Slow heart rate
• Abnormal fatigue
• Extreme weakness
• Chills
• Pinpoint eye pupils

The use of clonidine and chlorthalidone to treat hypertension may also lead to the excess loss of potassium. A patient should see their doctor at their earliest convenience once they start experiencing such a side effect, which manifests in the form of dryness of the mouth and an increased desire to drink water. Loss of potassium in the body may also cause various psychological effects, including mood fluctuations.

Other indicators of a significant potassium deficiency in a patient who is taking clonidine and chlorthalidone include:

• Inconsistent pulses of the heart
• Muscle cramps or pain
• Weak pulse
• Nausea and vomiting

Excessive loss of sodium is similarly in an indication that the clonidine and chlorthalidone medication a patient is taking may not be going too well. The signs and symptoms of the side effect include confusion of the mind, seizures, lower-than-normal mental activity levels, and irritability. A patient may also begin to feel unusually fatigued or weak.

Though less common, a patient using this medication may develop depression, which also necessitates medical/psychiatric remedies as soon as possible. Incidences of swollen lower legs and feet are not that common, but they may occur. Some rare such effects include coughing or huskiness, pain in the back, joints, or side, and change of skin and eye color to yellow.

It is very rare, but possible, for clonidine and chlorthalidone to cause a user to have black or tarry stools. If such a user notices blood in their urine or stool, they should suspect a bleeding problem that warrants urgent treatment. It is also infrequent for a patient on this medication to report vivid dreams or nightmares, super-tiny red spots on the skin, skin rashes, or pale or cold fingertips and toes.

Any occurrence of severe abdominal pain when taking clonidine and chlorthalidone demands emergency medical attention. A more significant underlying side effect may exist if nausea and vomiting accompany pain in the stomach while the victim is using these treatments. Unusual vulnerability to bruising and noticeable bleeding should set off alarm bells too.

There are specific clonidine and chlorthalidone side effects that need not send a user into panic mode whenever they occur. Typically, the hypertension medication the patient is taking is sufficient to help solve such problems without necessarily involving a physician. However, it still makes sense for the patient to consult their healthcare giver over any mild or severe treatment outcomes that fail to heal with time.

Examples of clonidine and chlorthalidone adverse effects that should typically go away with time:

• Constipation
• Dizziness
• Sleepiness
• Abnormal tiredness or weakness
• Dry mouth
• Low libido
• Loss of appetite
• Diarrhea
• Lightheadedness while rising from a sitting or lying posture
• Anxiety
• Stomach aches
• Itching/burning eyes

A hypertension victim on clonidine and chlorthalidone should also acknowledge the possibility that their treatment may still go on to produce specific side effects long after they have stopped taking it. Some of the possible post-treatment side effects are serious enough for the patient to see their doctor without delay. For instance, chest pain, persistent headache, and irregular heartbeats are potentially severe complications.

Other possible post-therapy clonidine and chlorthalidone side effects are:

• Nervousness
• Nausea/vomiting
• Restlessness
• Insomnia
• Abnormal sweating
• Surge of salivation
• Abdominal cramps
• Hand and finger shivers

Correct clonidine and chlorthalidone dosage and use

For starters, the combination of clonidine and chlorthalidone is not a first-line treatment option for hypertension. Instead, a physician may recommend it to a patient who has had no meaningful improvements despite trying a single-drug therapy. Nonetheless, the specific health situation of an individual patient helps a doctor decide the right dosage for their blood pressure problem.

Manufacturers of clonidine and chlorthalidone usually provide correct dosage directions on product labels. However, such information cannot override what the doctor prescribes for their patient. As such, a patient should never alter their dosage unless their doctor has recommended it.

How potent a drug is will also determine the ideal dosage for managing hypertension in a patient. In other words, clonidine and chlorthalidone tablets may differ in mass (milligrams), which dictates how many such tablets a patient should take in a day. Likewise, the nature and severity of the high blood pressure complication in an individual patient help the physician determine the right per-day dosage, the time interval between adjacent doses, and the duration for which a patient has to continue using the medication.

The clonidine and chlorthalidone therapy is administered orally in the form of tablets. When it comes to controlling hypertension, a patient may take a 15-mg chlorthalidone tablet and a 0.1-mg to a 0.3-mg tablet of clonidine once or twice per day. However, a doctor may prescribe a higher dosage depending on the circumstances of an individual patient, in which case, the maximum dose allowed is 30-mg chlorthalidone and 0.6-mg clonidine every day.

Any clonidine and chlorthalidone for children must follow the particular prescription the doctor ordered as there are no general/standard dosage instructions for giving these medicines to minors. Besides, patients requiring the drugs for liver or renal complications should see their doctor for appropriate dose adjustments.

A patient should stick to their daily dose as their doctor prescribed to ensure the stability of their blood pressure. Should they miss a dose of clonidine and chlorthalidone, they ought to take it at their earliest convenience. However, a patient should never take a double dose with the intention of making up for a missed one. The user should just revert to their usual dosing plan when the timing for taking a missed dose is too close to their next scheduled intake.

It may be difficult for a patient to compensate for two or more missed doses of clonidine and chlorthalidone. However, high blood pressure may escalate to a threatening state if a patient stays too long without taking their medication. Therefore, such an individual should see their doctor right away for help minimizing the risk of any unpleasant symptoms associated with multiple, successive missed doses.

Major drug interactions

Clonidine and chlorthalidone have hundreds of potential drug interactions, some moderate, others significant. With severe drug interactions, the possible effect on a patient may be acute or life-threatening. However, the health circumstances of a patient may necessitate the administration of two medicines despite their known interactions. In that case, the doctor may decide to adjust the dosage for one or both of the drugs with reactive properties.

Cisapride is an example of a drug that interacts with clonidine and chlorthalidone with potentially devastating outcomes for the patient. Typically, the two medicines do not usually go well with together. The interaction starts when chlorthalidone, a diuretic, causes a severe potassium deficiency in the bloodstream. Unfortunately, deficient potassium levels in the blood expose the victim to heart problems.

Cisapride/clonidine and chlorthalidone interactions may lead to an irregular heartbeat. The life of the patient may also be in danger. With the help of a doctor, the adverse interactions may be reversed and prevented in future by changing the dosage, stopping one of the medicines, or using a potassium supplement.

Other hypertension drugs have potential interactions with clonidine and chlorthalidone, so any patient using them should let their physician know. On a general note, the types of drugs in the list below can react with clonidine and chlorthalidone, making it essential to take appropriate precautions before combined use:

• Blood pressure medicines
• Lithium
• Digitalis
• Insulin or oral diabetes drug
• Antidepressants, including amitriptyline, amoxapine, and trimipramine

Drug interactions with clonidine and chlorthalidone can also impact the effectiveness of any other medication a patient is taking. For example, the dosage requirement for the drug that controls type 2 diabetes mellitus changes when a patient starts taking this hypertension regimen. Likewise, a diuretic that causes excessive discharge of water from the body in a patient with liver disease may escalate the complication.

Inflammation of the pancreas is also a pre-existing medical condition that could take a turn for the worse after a patient starts using clonidine and chlorthalidone. Similarly, the hypertension drugs increase uric acid levels in the blood, worsening the effects of gout. Reynaud’s syndrome and lupus erythematosus may also escalate.

These specific high blood pressure medicines may also have interactions with certain foods, beverages, and substances. A case in point is tobacco and alcohol. Alcohol may escalate some of the complications that these drugs cause.

The drugs in the list below are not usually for taking along with clonidine and chlorthalidone, unless necessary and as per the directives of a doctor:

• Aceclofenac
• Acemetacin
• Arsenic Trioxide
• Clomipramine
• Clonixin
• Crizotinib
• Desipramine
• Deslanoside
• Lumiracoxib
• Meclofenamate
• Nadolol
• Naproxen
• Nebivolol

A patient using any of the medications below while also taking clonidine and chlorthalidone increases their exposure to particular side effects. A doctor may still prescribe such drugs, but with the necessary dosage adjustments and precautionary measures.

• Cyclosporine
• Gossypol
• Mepivacaine
• Warfarin
• Fluphenazine


A patient should always inform their doctor about any other medication they are currently using. It makes it possible for the caregiver to take potential drug interactions into account when prescribing clonidine and chlorthalidone. Pre-existing medical conditions must also be reported to avoid treatment that may make them worse. For example, someone suffering from a renal disorder should let their doctor know because, if their condition is severe, chlorthalidone may be ineffective.

The immediate course of action after a patient notices unwanted symptoms of drug interactions is to contact their healthcare professional. For instance, an individual who experiences (or suspects) harmful effects due to clonidine and chlorthalidone interaction with cisapride may need to have their potassium levels checked for purposes of remediation in case of deficiency. A change of drug or dosage may also suffice.

Clonidine and chlorthalidone can itself deplete the amount of potassium in the blood to dangerous levels, making it critical for a patient to consider preemptive measures. As such, the doctor may recommend eating or drinking foods that are rich in potassium like oranges. Potassium supplementation or using another drug that will prevent loss of the mineral from the outset may also work.

Under no circumstances should a patient stop using or change the dosage of clonidine and chlorthalidone on their own accord even if they have noticed potentially dangerous side effects or drug interactions. The best approach to hypertension management involves a patient working closely with their doctor. It enables the caregiver, who is aware of all potential concerns for using this medication, to continue monitoring it and providing appropriate medical directions/interventions in case of anything.

Clonidine and chlorthalidone require a step by step, tapered withdraw once therapeutic benefits begin to materialize or a patient has to stop using the medication for any other valid reason. Stopping the treatment at once may lead to anxiety, acute hypertension, or other life-threatening complications. Only a doctor can assess a patient and decide that it is safe for them to begin a gradual withdrawal from their blood pressure medication.

Any likely health improvements after taking clonidine and chlorthalidone for some time are no safe or good reason to stop the treatment. Typically, hypertension has no symptoms, and some people do not realize they have had it all along until they are being treated or examined for a blood pressure-related complication such as stroke, by which time it is usually too late to prevent the resultant disorder.

A patient should see their physician for help fixing any abnormally high loss of water in the body through persistent vomiting, diarrhea, or too much sweating. Using clonidine and chlorthalidone can quickly lead to dehydration, exposing the victim to the risk of extremely low blood pressure or dangerous electrolyte imbalance. Similarly, it helps to avoid any unnecessary activity or exposure that leads to loss of body water. Such exercises include dehydrating physical workouts in hot weather.

Regular blood pressure checkups are necessary to see if the administered hypertension medication is doing its job. A patient should attend all scheduled exams. Also, urine and blood tests are essential in case of ongoing vomiting or diarrhea. Even a patient using chlorthalidone should let their doctor know it during a thyroid exam as the drug can impact test results.

Overdosing on clonidine and chlorthalidone is potentially fatal, so any such incidence warrants emergency medical intervention. A patient may suspect that they have taken too much of the drugs when they experience unexpected symptoms such as convulsions, nausea, and sleepiness. Breathing problems and a decrease in the heart rate may also indicate a possible clonidine and chlorthalidone overdose.

Clonidine and chlorthalidone affect the central nervous systems, with effects such as slowed thinking, and reaction. The therapy also causes drowsiness. When under the influence of this medication, a user should avoid or be sure they can manage activities that require high concentration levels and excellent reaction times, such as driving and machine operations.

When taking clonidine and chlorthalidone, some people may suffer sunburns owing to an increase in the sensitivity of their skin to the rays of the sun. A practical solution is to steer clear of direct sunlight, or machine-generated ultra violate rays. Protective wear, as well as any sunscreen with an SPF of 15 and above, may also help in the outdoors.

No comprehensive research currently guarantees the safety or risks of taking clonidine and chlorthalidone during pregnancy. So a doctor recommends the regimen in a pregnant patient only when its potential therapeutic benefits defeat the danger. A lactating mother should be wary of the tendency of the drug to contaminate human milk, in which case, their doctor advises discontinuation of either the breastfeeding or hypertension medicine.


A sealed container is most appropriate for storing clonidine and chlorthalidone. If possible, the container should be kept in a lockable prescription pill box or cabinet to prevent minors from accessing the drugs. There have been cases of children fatalities after they accidentally took these high blood pressure medications.

Room temperature storage guarantees that the drugs retain their therapeutic benefits and remain safe for use before expiry. It is therefore imperative not to expose the tablets to heat or direct sunlight. For example, the kitchen is not the ideal place to store these hypertension remedies.

It is equally essential for the drugs to avoid any wetness or moisture, which can instantly destroy them by dissolving, chemical reactions, or otherwise. Extreme cold is also not an ideal condition for keeping these medicines.

Once a patient has stopped taking clonidine and chlorthalidone, of course without jeopardizing their health, they should safely dispose of them. Expired drugs require the same handling in an environmentally-friendly manner.


Clonidine and chlorthalidone is a medication for controlling high blood pressure. It is a fall-back regimen in case monotherapy has failed to produce the desired therapeutic effects in a hypertensive patient. The patient has to continue using the medicine daily as the doctor ordered to keep their blood pressure low and prevent incidences such as heart attack or stroke.

The medication has numerous side effects that may or may not require the intervention of a doctor. To be on the safe side, the patient discusses all such adverse treatment outcomes with their physician so that they know what to do each time undesirable symptoms come up. It is also imperative for the patient to inform their doctor about all other medication they are currently using, and any other condition for which they are presently undergoing treatment.

Equally important, an individual may not suddenly stop using clonidine and chlorthalidone after they have started. Doing so may cause life-threatening effects on top of anxiety and extremely high blood pressure. When the doctor determines that it is time to quit the medication, a tapered withdrawal ensues to protect the patient.