Clonidine (Oral)

Clonidine is a prescription only drug that is used to treat high blood pressure in patients.


It is part of a group of drugs called the antihypertensives, which work within the brain to rewire some of the body's nerve impulses. This activity relaxes the blood vessels, enabling the blood to flow through them more easily, which lowers the pressure of the blood flowing around the body.

High blood pressure is also known as hypertension. This happens when the blood vessels become contracted, leaving a smaller area for the blood to pass through. With the heart still pumping blood through the vessels at the same speed, this results in increased pressure in the blood vessels, as blood forces its way through the body. It also means that more blood and oxygen reach the heart.

High blood pressure is a common condition that is typically more often diagnosed in older people, and is also linked to other conditions, such as type 2 diabetes. A higher pressure in the blood also decreases the amount of oxygen that reaches the heart, resulting in a poorer all-round health.

If high blood pressure is left untreated for a long period of time, it can increase the workload of the heart and arteries, as well as restricting the flow of blood to other vital organs. This can lead to serious and chronic health complications that can have life-threatening complications.

High blood pressure may also decrease the quality of life for its sufferers, with symptoms typically including difficulty breathing, lack of energy, heart problems and physical exertion.

Clonidine is not a cure for high blood pressure; however, it is very effective at controlling the condition. The drug is sometimes prescribed with other drugs that can help return blood pressure to a normal level. However, those with high blood pressure are advised to also treat their condition by making positive lifestyle changes, including improving their diet and exercise regimes. High blood pressure can be avoided by engaging in a healthy and active lifestyle and cutting out processed foods; those that are vulnerable to the condition, or have started to develop it, can help to prevent it or lessen the severity themselves.

Clonidine is designed to be a long-term medication that some patients may take to control their blood pressure levels for the rest of their lives.

Clonidine is sold and marketed under three brand names in the US. These brand names all contain the same medication, but are manufactured through different pharmaceutical companies. These are:

  • Catapres
  • Kapvay
  • Nexiclon XR

Kapvay is also occasionally used to treat attention deficit hyperactivity disorder (ADHD) within children and adults. The medicine works by reducing the restlessness in children and adult patients and improving their attention spans. The drug is often prescribed as one part of a holistic treatment plan for those that find concentration difficult and are generally considered overactive. It is often recommended along with forms of therapy and occasionally special needs education (for children).

Type of medication

  • Tablet, extended release
  • Suspension, extended release
  • Tablet

Conditions treated

Side effects

When you start a new medication, you may experience some side effects as your body gets used to the effect of the new drug in your system. Not every patient will experience the full breadth of side effects, but having at least one is considered to be fairly common in the early days of your treatment plan. If any of your side effects persist, or if you consider them to be unmanageable, seek some advice from your health care professional.

If you experience any of the following side effects, you should contact your doctor for advice immediately, as these may be signs of a severe adverse reaction to the drug or a developing health condition:

  • Change in mood, or depression
  • Swelling in the lower legs and feet
  • Anxiety, panic attacks or general nervousness
  • Pain or discomfort in the chest
  • Skin reactions, such as burning sensation, blistering, flakiness, dryness or crustiness
  • Confusion of the mind
  • Inability to pass urine, or difficulty in fully emptying the bladder
  • Dry mouth
  • Change in heartbeat, such as an increase, decrease or irregularities
  • Pounding heartbeat or pulse
  • Drowsiness or tiredness
  • Dilated veins in the neck
  • Signs of the common cold or flu, including fever
  • Hyperventilation
  • Achiness or feeling of being rundown or ill
  • Irregularities in the breathing
  • Swelling in the skin, soreness, redness itchiness or scaling
  • Hives and swelling in areas of the face, such as lips, tongue, throat, eye area or eyelids
  • Swelling of the sexual organs, hands, feet or legs
  • Fainting or dizziness
  • Inability to feel warm coldness can be experienced particularly in the extremities (hands, fingers, feet, toes and nose)
  • Pale or washed-out looking skin
  • Increase in the amount of urine, or increase in frequency of needing to urinate
  • Shortness of breath, even after very mild exertion
  • Vivid nightmares or dreams
  • Shakiness in any part of the body
  • A feeling that you are seeing or experiencing things that are not actually there (hallucinations)
  • Difficulty getting to sleep, or interrupted sleep (insomnia)
  • Over excited feelings, or restlessness
  • Wheezing or persistent coughing
  • Tightness in the chest
  • Rapid or sudden weight gain

A list of less serious side effects is given below. If you experience any of these symptoms at the start of your treatment, you should not require medical attention in most cases. However, these side effects would normally subside after a couple of weeks and, if they do not, you should seek medical advice:

  • Constipation
  • Nausea or vomiting
  • Decreased libido
  • Difficulty maintaining an erection or engaging in sexual intercourse
  • Discomfort in the eyes, such as burning, soreness, itching or dryness
  • Decrease in appetite
  • Darkening of the skin (not linked to sun exposure)
  • Blurry vision
  • Hair loss
  • Thinning of the hair on various parts of the body
  • Cramps, particularly in the leg muscles
  • Pain in the joints or muscles
  • Swelling or soreness of the breast in both men and women
  • General feeling of weakness, in the muscles and or the bones

The most common side effects are usually related to blood pressure (hypotension). This condition occurs in approximately 45% of patients. The second most common is a dry mouth, which occurs in the early stages for around 40% of those taking the medication. Drowsiness is reported in around one third of patients and 16% will experience dizziness. Around 10% will experience sedative effects or constipation.

Contact a pharmacist for lighter, over the counter medication that can be used to ease the discomfort you may experience as a result of these side effects, but always tell your pharmacist that you are taking clonidine as there may be some regular medications that will be unsuitable to take in conjunction.


The dosage of clonidine that is given to each patient will vary according to medical history, age, medical condition and how severe the patient's high blood pressure is. A higher dosage may be prescribed initially, and then potentially increased to a maintenance dose.

You should always follow the individual instructions for administration that will be printed on your prescription label. Always stick to the dosage that is prescribed to you by your doctor; do not attempt to increase or decrease the dosage yourself. If you think it needs to be adjusted, you should book an appointment with your doctor to discuss the reasons why.

Clonidine works best when you take each dose on time. You should take two tablets per day, one in the morning and one at bedtime.

You should not stop taking clonidine of your own accord, especially not suddenly. If you do so, you could experience unwanted side effects, such as dizziness, nervousness, anxiety or nausea. Call your doctor immediately if you lose your prescription, as you will need to pick up an emergency supply straight away to avoid withdrawal symptoms.

The tablets come in 0.1 mg potency, and patients are usually initially required to take two per day, one at the start and one at the end of the day. As the body becomes used to the drug, and depending on how the blood pressure levels respond, your doctor may prescribe you a further increment of 0.1 mg per day, at weekly intervals.

Typical dosages given at maintenance level range between 0.2 mg and 0.6 mg per day. The maximum dosage that should be prescribed per day is 2.4 mg. However, dosages at this level are extremely rare and should only be given in the most severe or exceptional cases.

Major drug interactions

If you are taking any other medications, it is very important that you let your doctor know before you start taking clonidine. This is because some drugs can react with each other (called a drug interaction) and cause unwanted or even dangerous side effects. Interactions are grouped into three categories minor, moderate and major. Major interaction combinations should be avoided at all times as the risk has been found to outweigh the health benefits. These are the drugs that have a major reaction with clonidine and, therefore, should be avoided for consumption at the same time:

  • acebutolol
  • acetaminophen, propoxyphene
  • Adapin (doxepin)
  • AK Beta (levobunolol ophthalmic)
  • amitriptyline
  • amitriptyline, chlordiazepoxide
  • amitriptyline, perphenazine
  • amoxapine
  • Anafranil (clomipramine)
  • Asendin (amoxapine)
  • aspirin, caffeine, propoxyphene
  • atenolol
  • atenolol, chlorthalidone
  • Aventyl Hydrochloride (nortriptyline)
  • Balacet (acetaminophen, propoxyphene)
  • bendroflumethiazide, nadolol
  • Betagan (levobunolol ophthalmic)
  • Betagan C-Cap (levobunolol ophthalmic)
  • Betapace (sotalol)
  • Betapace AF (sotalol)
  • betaxolol
  • betaxolol ophthalmic
  • Betaxon (levobetaxolol ophthalmic)
  • Betimol (timolol ophthalmic)
  • Betoptic (betaxolol ophthalmic)
  • Betoptic S (betaxolol ophthalmic)
  • bisoprolol
  • bisoprolol, hydrochlorothiazide
  • Blocadren (timolol)
  • Brevibloc (esmolol)
  • brimonidine, timolol ophthalmic
  • Bystolic (nebivolol)
  • Byvalson (nebivolol, valsartan)
  • carteolol
  • carteolol ophthalmic
  • Cartrol (carteolol)
  • carvedilol
  • clomipramine
  • Combigan (brimonidine, timolol ophthalmic)
  • Coreg (carvedilol)
  • Coreg CR (carvedilol)
  • Corgard (nadolol)
  • Corzide (bendroflumethiazide, nadolol)
  • Corzide 40, 5 (bendroflumethiazide, nadolol)
  • Corzide 80, 5 (bendroflumethiazide, nadolol)
  • Cosopt (dorzolamide, timolol ophthalmic)
  • Cosopt PF (dorzolamide, timolol ophthalmic)
  • Darvocet A500 (acetaminophen, propoxyphene)
  • Darvocet-N 100 (acetaminophen, propoxyphene)
  • Darvocet-N 50 (acetaminophen, propoxyphene)
  • Darvon (propoxyphene)
  • Darvon Compound 32 (aspirin, caffeine, propoxyphene)
  • Darvon Compound-65 (aspirin, caffeine, propoxyphene)
  • Darvon-N (propoxyphene)
  • desipramine
  • dorzolamide, timolol ophthalmic
  • doxepin
  • doxepin topical
  • Duo-Vil (amitriptyline, perphenazine)
  • Dutoprol (hydrochlorothiazide, metoprolol)
  • Elavil (amitriptyline)
  • Endep (amitriptyline)
  • esmolol
  • Etrafon (amitriptyline, perphenazine)
  • Etrafon Forte (amitriptyline, perphenazine)
  • Hemangeol (propranolol)
  • hydrochlorothiazide, metoprolol
  • hydrochlorothiazide, propranolol
  • hydrochlorothiazide, timolol
  • imipramine
  • Inderal (propranolol)
  • Inderal LA (propranolol)
  • Inderal XL (propranolol)
  • Inderide (hydrochlorothiazide, propranolol)
  • Inderide LA (hydrochlorothiazide, propranolol)
  • InnoPran XL (propranolol)
  • Istalol (timolol ophthalmic)
  • Kerlone (betaxolol)
  • labetalol
  • Levatol (penbutolol)
  • levobetaxolol ophthalmic
  • levobunolol ophthalmic
  • Limbitrol (amitriptyline, chlordiazepoxide)
  • Limbitrol DS (amitriptyline, chlordiazepoxide)
  • Lopressor (metoprolol)
  • Lopressor HCT (hydrochlorothiazide, metoprolol)
  • metipranolol ophthalmic
  • metoprolol
  • Metoprolol Succinate ER (metoprolol)
  • Metoprolol Tartrate (metoprolol)
  • nadolol
  • nebivolol
  • nebivolol, valsartan
  • Normodyne (labetalol)
  • Norpramin (desipramine)
  • nortriptyline
  • Ocupress (carteolol ophthalmic)
  • OptiPranolol (metipranolol ophthalmic)
  • Pamelor (nortriptyline)
  • PC-CAP (aspirin, caffeine, propoxyphene)
  • penbutolol
  • pindolol
  • PP-Cap (propoxyphene)
  • Propacet 100 (acetaminophen, propoxyphene)
  • propoxyphene
  • Propoxyphene Compound 65 (aspirin, caffeine, propoxyphene)
  • propranolol
  • protriptyline
  • Prudoxin (doxepin topical)
  • Sectral (acebutolol)
  • Silenor (doxepin)
  • Sinequan (doxepin)
  • sodium oxybate
  • Sorine (sotalol)
  • sotalol
  • Sotalol Hydrochloride AF (sotalol)
  • Sotylize (sotalol)
  • Surmontil (trimipramine)
  • Tenoretic (atenolol, chlorthalidone)
  • Tenoretic 100 (atenolol, chlorthalidone)
  • Tenoretic 50 (atenolol, chlorthalidone)
  • Tenormin (atenolol)
  • Timolide (hydrochlorothiazide, timolol)
  • Timolide 10-25 (hydrochlorothiazide, timolol)
  • timolol
  • timolol ophthalmic
  • Timoptic (timolol ophthalmic)
  • Timoptic Ocudose (timolol ophthalmic)
  • Timoptic-XE (timolol ophthalmic)
  • tizanidine
  • Tofranil (imipramine)
  • Tofranil-PM (imipramine)
  • Toprol-XL (metoprolol)
  • Trandate (labetalol)
  • Triavil (amitriptyline, perphenazine)
  • trimipramine
  • Trycet (acetaminophen, propoxyphene)
  • Vanatrip (amitriptyline)
  • Visken (pindolol)
  • Vivactil (protriptyline)
  • Wygesic (acetaminophen, propoxyphene)
  • Xyrem (sodium oxybate)
  • Zanaflex (tizanidine)
  • Zebeta (bisoprolol)
  • Ziac (bisoprolol, hydrochlorothiazide)
  • Zonalon (doxepin topical)


Food and alcohol interactions

It is not advisable to consume alcohol when you are taking clonidine. People that take alcohol and clonidine at the same time risk a sedative effect, which can include excessive tiredness, sleepiness, dizziness or accommodation disorder. This sedating effect may become more severe the more the two substances are taken together, and may impact the patient's ability to carry out high risk tasks, such as operating machinery and driving.

Patients who consume alcohol while taking this treatment course also risk their blood pressure becoming too low. If you do decide to consume alcohol, introduce it slowly and in small to moderate quantities, and take extra time before driving to ensure that the alcohol has left your system.

Disease interactions

Clonidine is not suitable for everyone, and you may have other diseases or conditions that may make it dangerous or ineffective to take the medication. There are four diseases and conditions that have been found to have a serious interaction with clonidine; if you have any other these, you may be at a much greater risk of developing health complications. If you have any of the following conditions, your doctor may recommend a different course of treatment:


Clonidine may reduce sympathetic outflow from the central nervous system (CNS), leading to a slower heart rate and conditions like sinus bradycardia. Clonidine may not be suitable for people that have conduction disturbances or AV nodal disease. Clonidine has a moderate interaction with these conditions.


Clonidine can cause a deterioration of the mental state, leading to depression, in some cases. The interaction has been classed as moderate, so administration may not be suitable for patients that have a history of mental illnesses or depression.


Clonidine is used to lower blood pressure, so it may lead to the condition hypotension, which is when the blood pressure becomes too low. Patients who have had a condition related to hypotension in the past may not be suitable candidates for this treatment method.

Renal dysfunction

This condition has a moderate interaction with clonidine, so patients with renal dysfunction may need to receive a reduced dosage if their condition is severe.

Always tell your doctor if you have a history of heart disease, a heart rhythm disorder, slow heartbeats, heart attack, stroke, low blood pressure, severe coronary artery disease, kidney disease or any allergies.


Always tell your doctor if you have allergies to clonidine or any other medications. It is also very important that you mention if you have ever had an allergic reaction to a clonidine TTS transdermal skin patch.

Mental alertness

Clonidine has been known to affect metal alertness in some patients. You may find that the drug impairs your reactions to and thinking in certain situations. When you start taking the medication, you should refrain from driving or any other potentially dangerous manual tasks until you are sure your body has adapted to the medication being in your system. If you think that your judgement has been severely impaired as a result of taking this medication, you should consult your doctor for advice; if the symptoms persist, you may need to be put onto a different medication.

Geriatric patients

Although this drug has been found to be just as effective for older patients as it is for younger adults, there may be increased risks associated with the drug in geriatric patients. This is because older patients may be more sensitive to the impact of the drug and may develop increased side effects or other health complications.


It is not suitable to administer clonidine to anyone under the age of 18. This is because children may be more vulnerable to the impact of this strong drug and suffer more prominent side effects.

Pregnancy and breastfeeding

Although there are no medical studies that suggest a risk to the fetus if taken by an expectant mother, administering it to those that are pregnant should be approached with caution. Doctors should monitor their patients and the fetus closely throughout the pregnancy and, if there are any unusual signs or complications, use of the medication may be stopped.

It is not suitable for breastfeeding mothers to take this medication as the substance can pass into breast milk and be consumed by the baby. If you are nursing a baby, tell your doctor and an alternative treatment may be given.


If you are prescribed clonidine, you should always store it in a safe place that is out of the reach of children. Drug consumption by children is a serious problem in the US, with more than 60,000 children being admitted to emergency rooms throughout the country each year as a result of them taking medicines that were not meant for them. You can help to reduce that number by keeping your prescription and over the counter medications in a lockable cupboard and, if they are supplied in a childproof container, by keeping the tubs locked when not in use.

The ideal storage conditions for clonidine are room temperature approximately 20 to 25 degrees but they have a range of between 15 and 30 degrees Celcius.

You should keep your tablets away from direct sources of sunlight, as well as away from heat sources, such as radiators. You should also keep the prescription medication away from moisture, so try not to store them in the bathroom, where it can become damp.


Provided all the usage instructions for taking clonidine are followed, the drug can be an effective and fairly safe form of treatment. If the body responds positively to the drug and blood pressure is successfully lowered, it may be used as a long-term treatment that can help to control blood pressure for the rest of the patient's life.

However, it should be noted and made clear to the patient that clonidine is not a cure for high blood pressure. The condition is usually chronic; a treatment will be sought that can control it for the foreseeable future. Clonidine can be used on its own or with other drugs to treat high blood pressure, depending on the severity of the condition. For severe cases, the drug may not be enough on its own to lower the blood pressure.

Clonidine is most effective when it is taken by a patient who also makes positive changes to their lifestyle. Those suffering from high blood pressure can help to lessen their condition by improving their diet to include the recommended intake of fruits, vegetables and high alkaline foods. Patients should cut out any harmful foods, such as over processed foods, sugary drinks, fizzy pop and overly fatty foods. It is also strongly advisable that the patient starts an exercise regime, to increase the flow of blood and oxygen around the body and improve overall health.

Clonidine is effective for use in almost all adults. There has not yet been found to be a major risk presented for use during pregnancy, and it can be taken across all adult age groups. However, it has been found that older patients (those over the age of 75) may be more vulnerable to certain side effects and may require a lower dose as a result. Studies have found that this medication is not suitable for those under the age of 18, as children may be at too high a risk from serious side effects compared to adults.

Clonidine is a fairly strong drug, so it is important that dosage instructions are adhered to and that the patient takes each tablet at the same times every day. This is particularly important as the drug is a long-term treatment and relies heavily on the ability of the patient to keep up the habit of taking it daily. There are also a large number of other drugs that can interact with this one, so patients and doctors should discuss any other medications prescribed for high blood pressure or any other condition to check safety and suitability.