How does this medication work? What will it do for me?

Clonidine belongs to the group of medications called antihypertensives or vascular stabilizers. It is used alone or in combination with thiazide diuretics (e.g., hydrochlorothiazide) to treat high blood pressure. It is usually tried when other types of blood pressure medications are ineffective or cannot be used. This medication works by widening the blood vessels, which increases blood flow and lowers blood pressure.

Clonidine can also be used to relieve menopausal hot flashes when hormone replacement therapy is not needed or not desired. For hot flashes, clonidine works by helping reduce the response of the blood vessels to stimuli that cause them to narrow and widen.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

0.025 mg
Each blue, round, biconvex, film-coated tablet, engraved "N" on one side and plain on the other side, contains 0.025 mg clonidine hydrochloride. Nonmedicinal ingredients: colloidal silicon dioxide, dibasic calcium phosphate, lactose monohydrate (spray dried), magnesium stearate, pregelatinized starch, FD&C Blue No. 2, hypromellose, polyethylene glycol, polyvinyl alcohol - partially hydrolyzed, talc, and titanium dioxide.

This medication is also available as 0.1 mg and 0.2 mg tablets.

How should I use this medication?

For treatment of high blood pressure, the usual starting dose of clonidine is 0.1 mg twice daily, taken in the morning and at bedtime. After 2 to 4 weeks, your doctor may increase your dose gradually by 0.1 mg per day. The usual dose ranges from 0.1 mg to 0.3 mg twice daily.

The tablets should be swallowed whole with water.

Do not stop taking this medication suddenly without checking with your doctor.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature and keep it out of the reach of children.

This medication is available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms listed here. The forms available for the specific brand you have searched are listed under "What form(s) does this medication come in?"

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take this medication if you:

  • are allergic to clonidine or any ingredients of this medication
  • have a certain type of abnormal heart rhythm associated with a low heart rate

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • agitation
  • changes in sexual function
  • constipation
  • dizziness
  • drowsiness
  • dry mouth
  • feeling unwell
  • headache
  • loss of appetite
  • nausea and vomiting
  • nervousness
  • tiredness
  • weakness
  • weight gain

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • confusion
  • depression
  • difficulty urinating
  • dizziness, lightheadedness, or fainting - especially when getting up from a lying or sitting position
  • joint pain
  • muscle pain or cramps
  • pounding or fast heart rate
  • paleness or cold feeling in fingertips and toes
  • seeing or hearing things that are not there (hallucinations)
  • signs of liver problems such as nausea, vomiting or dark urine
  • skin rash
  • slow heart rate

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • signs of a serious allergic reaction (e.g., hives; difficulty breathing; or swelling of the face, mouth, tongue, or throat)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Depression: If you have a history of depression, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Drowsiness/reduced alertness: Clonidine can cause drowsiness. Do not drive or operate other machinery until you have determined that this medication does not affect your ability to perform these tasks.

Eyes: This medication may affect the eye. People taking clonidine should receive periodic eye examinations. Because this medication can cause decreased tear production, and contact lenses may become uncomfortable to wear.

Heart or blood vessel disease: Because this medication lowers blood pressure, if you have severe heart disease or blood vessel disease, a recent heart attack or stroke, or a slow heart rate, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Kidney function: If you have reduced kidney function, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Lactose: This medication may contain lactose. People with conditions associated with galactose intolerance should not take this medication.

Other medical conditions: If you have polyneuropathy or constipation, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Raynaud's disease: If you have Raynaud's disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Withdrawal: Don't stop taking this medication without talking to your doctor. A severe withdrawal reaction may develop within 12 to 48 hours when clonidine is stopped suddenly. This reaction includes a rapid rise in blood pressure and symptoms such as nervousness, agitation, restlessness, pounding heartbeat, nausea, and headache.

When stopping clonidine therapy, your doctor will instruct you to reduce the dose gradually over 2 to 4 days to avoid this reaction. A withdrawal reaction is most likely to occur in people who have been receiving large doses of clonidine or who are taking another type of blood pressure medication called a beta-blocker (e.g., atenolol, metoprolol, bisoprolol) at the same time.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if clonidine passes into breast milk. This medication is not recommended for women who are breast-feeding.

Children: The safety and effectiveness of using this medication have not been established for children.

What other drugs could interact with this medication?

There may be an interaction between clonidine and any of the following:

  • ACE inhibitors (e.g., ramipril, enalapril, lisinopril)
  • alcohol
  • alpha-blockers
  • barbiturates (e.g., phenobarbital)
  • beta-blockers (e.g., atenolol, metoprolol)
  • calcium channel blockers (e.g., diltiazem, verapamil)
  • chlorpromazine
  • digoxin
  • diuretics (e.g., furosemide, hydrochlorothiazide)
  • epinephrine
  • furosemide and other diuretics (water pills)
  • MAO inhibitors (e.g., phenelzine, tranylcypromine)
  • methylphenidate
  • mirtazapine
  • neuroleptics (e.g., haloperidol, fluphenazine)
  • nitroprusside
  • nonsteroidal anti-inflammatory drugs (NSAIDs; e.g., indomethacin, naproxen, diclofenac)
  • phentolamine
  • prazosin
  • pseudoephedrine
  • rituximab
  • tolazoline
  • tricyclic antidepressants (e.g., amitriptyline, imipramine)

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.