Clonidine

Brand names

• Apo-Clonidine
• Catapres
• Catapres-TTS
• Combipres [CD]
• Dixarit
• Duraclon
• Novo-Clonidine
• Nu-Clonidine

Usage

To treat high blood pressure (hypertension). Also used for relief of menopausal flushing.

How it works

Clonidine acts upon certain areas of the central nervous system (the brain and spinal cord) that regulate the activity of the heart and the smooth muscle tissue surrounding the arteries. It causes the blood vessels to relax and widen, which lowers blood pressure. It reduces the response of peripheral blood vessels to stimuli.

Side effects

Serious

Serious side effects are less likely when clonidine is used as directed.

Common

Dry mouth, reduced saliva, reduced tear production (caution for contact lens users), drowsiness, dizziness, constipation.

Less common

Mental depression, swelling of feet and lower legs, pale or cold fingertips and toes, vivid dreams or nightmares, hair loss.

Possible interactions

Other medicaments:

Clonidine may decrease the effects of:

• levodopa (Larodopa, Sinemet, etc.), causing an increase in parkinsonism symptoms.

Clonidine taken concurrently with:



• beta-adrenergic-blocking medicaments (Inderal, Lopressor, etc.) may increase rebound hypertension risk if clonidine is stopped first. It is best to stop the beta-blocker first and then withdraw clonidine gradually.
• cyclosporine (Sandimmune) may lead to cyclosporine toxicity.
• ephedrine (various) may dangerously increase the blood pressure raising effect of ephedrine.
• naloxone (Narcan, Talwin NX) may blunt the therapeutic effect of clonidine and result in a hypertensive response.
• niacin may decrease the facial-flushing side effect of niacin.
• nonsteroidal anti-inflammatory medicaments (NSAIDs) may blunt blood pressure lowering benefits of clonidine.
• verapamil (Calan, others) may lead to problems in conduction of the heart.

The following medicaments may decrease the effects of clonidine:



• nonsteroidal anti-inflammatory medicaments.
• tricyclic antidepressants (Elavil, Sinequan), possibly reducing clonidine's effectiveness in lowering blood pressure.

Foods:

Avoid excessive salt and ask your doctor for help with salt restriction.

Herbal medicines or minerals:

Ginseng may increase blood pressure, blunting the benefits of this medicine. Hawthorn, saw palmetto, ma huang, goldenseal, yohimbe and licorice may also cause increased blood pressure. Calcium and garlic may help lower blood pressure and Indian snakeroot has a German Commission E monograph indication for hypertension-talk to your doctor to see if those combinations may allow some lowering of prescription medicine doses. Eleuthero root  should be avoided by people living with hypertension.

Alcohol:

Combined effects can cause marked drowsiness and exaggerated reduction of blood pressure.

Exposure to heat:

Hot environments may reduce blood pressure, making orthostatic hypotension more likely.

Exposure to cold:

May cause painful blanching and numbness of the hands and feet on exposure to cold air or water (Raynaud's phenomenon).

Exposure to environmental chemicals:

This medicament may intensify the hypertensive response to isometric exercise. Ask your doctor for help.

Occurrence of unrelated illness:

Fever may lower blood pressure. Repeated vomiting may prevent the regular use of this medicament and cause an acute withdrawal reaction. Consult your physician.

Discontinuation:

Do not stop this medicament suddenly. A severe withdrawal reaction can occur within 12 to 48 hours after the last dose. It is best to gradually decrease the dose over 3 to 4 days, and check blood pressure often.