Chlorthalidone / Clonidine Side Effects

Medically reviewed by Drugs.com. Last updated on Aug 15, 2023.

Applies to chlorthalidone / clonidine: oral tablet.

Other side effects

Some side effects of chlorthalidone / clonidine may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects.

Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common side effects

• constipation
• dizziness
• drowsiness
• dryness of mouth
• unusual tiredness or weakness

Less common side effects

• decreased sexual ability
• diarrhea
• dizziness or lightheadedness when getting up from a lying or sitting position
• dry, itching, or burning eyes
• increased sensitivity of skin to sunlight
• loss of appetite
• nausea or vomiting
• nervousness
• upset stomach

After you stop using this medicine, it may still produce some side effects that need attention. During this period of time, Check with your doctor immediately if you notice the following side effects:

• anxiety or tenseness
• chest pain
• fast or pounding heartbeat
• headache
• increased salivation
• nausea
• nervousness
• restlessness
• shaking or trembling of hands and fingers
• stomach cramps
• sweating
• trouble in sleeping
• vomiting

Serious side effects

Along with its needed effects, chlorthalidone/clonidine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking chlorthalidone / clonidine:

Signs and symptoms of overdose

• difficulty in breathing
• dizziness (extreme) or faintness
• feeling cold
• pinpoint pupils of eyes
• slow heartbeat
• unusual tiredness or weakness (extreme)

Check with your doctor as soon as possible if any of the following side effects occur while taking chlorthalidone / clonidine:

Signs and symptoms of too much potassium loss

• dryness of mouth
• increased thirst
• irregular heartbeat
• mood or mental changes
• muscle cramps or pain
• nausea or vomiting
• weak pulse

Signs and symptoms of too much sodium loss

• confusion
• convulsions (seizures)
• decreased mental activity
• irritability
• muscle cramps
• unusual tiredness or weakness

Less common side effects

• mental depression
• swelling of feet and lower legs

Rare side effects

• black, tarry stools
• blood in urine or stools
• cough or hoarseness
• fever or chills
• joint pain
• lower back or side pain
• paleness or cold feeling in fingertips and toes
• pinpoint red spots on skin
• skin rash or hives
• stomach pain (severe) with nausea and vomiting
• unusual bleeding or bruising
• vivid dreams or nightmares
• yellow eyes or skin

For healthcare professionals

Applies to chlorthalidone / clonidine: oral tablet.

General adverse events

The most frequent adverse reactions were dry mouth, drowsiness, dizziness, constipation, and sedation.^[Ref]

Gastrointestinal

• Very common (10% or more): Dry mouth (up to 40%), constipation (up to 10%)

Chlorthalidone:

• Frequency not reported: Gastric irritation, nausea, vomiting, cramping, diarrhea, constipation, pancreatitis

Clonidine:

• Common (1% to 10%): Nausea, vomiting
• Frequency not reported: Parotitis^[Ref]

Nervous system

• Very common (10% or more): Drowsiness (up to 33%), dizziness (up to 16%), sedation (up to 10%)

Chlorthalidone:

• Frequency not reported: Dizziness, vertigo, paresthesias, headache

Clonidine:

• Common (1% to 10%): Headache^[Ref]

Other

Chlorthalidone:

• Frequency not reported: Weakness

Clonidine:

• Very common (10% or more): Weakness (up to 10%)
• Common (1% to 10%): Malaise, fatigue, discontinuation syndrome
• Uncommon (0.1% to 1%): Gynecomastia
• Frequency not reported: Dryness, increased sensitivity to alcohol, fever^[Ref]

Cardiovascular

Chlorthalidone:

• Frequency not reported: Necrotizing angiitis, orthostatic hypotension

Clonidine:

• Common (1% to 10%): Orthostatic symptoms
• Uncommon (0.1% to 1%): Palpitations, tachycardia, bradycardia
• Frequency not reported: Raynaud's phenomenon, congestive heart failure, ECG abnormalities, sinus bradycardia, atrioventricular block, pallor^[Ref]

Dermatologic

Chlorthalidone:

• Frequency not reported: Purpura, photosensitivity, rash, urticaria, Lyell's syndrome

Clonidine:

• Common (1% to 10%): Rash
• Uncommon (0.1% to 1%): Pruritus, hives, angioneurotic edema, urticaria, alopecia^[Ref]

Genitourinary

Chlorthalidone:

• Frequency not reported: Glycosuria, impotence

Clonidine:

• Common (1% to 10%): Sexual activity decreased, impotence, nocturia
• Uncommon (0.1% to 1%): Difficulty in micturition, urinary retention^[Ref]

Hematologic

Chlorthalidone:

• Frequency not reported: Leukopenia, agranulocytosis, thrombocytopenia, aplastic anemia

Clonidine:

• Frequency not reported: Weakly positive Coombs' test^[Ref]

Hepatic

Chlorthalidone:

• Frequency not reported: Intrahepatic cholestatic jaundice

Clonidine:

• Common (1% to 10%): Mild transient abnormalities in liver function tests
• Frequency not reported: Hepatitis^[Ref]

Metabolic

Chlorthalidone:

• Frequency not reported: Anorexia, hyperglycemia, hyperuricemia

Clonidine:

• Common (1% to 10%): Anorexia, weight gain
• Frequency not reported: Transient elevation of blood glucose^[Ref]

Musculoskeletal

Chlorthalidone:

• Frequency not reported: Muscle spasm

Clonidine:

• Uncommon (0.1% to 1%): Muscle or joint pain, cramps of the lower limbs
• Frequency not reported: Transient elevation of serum creatine phosphokinase^[Ref]

Ocular

Chlorthalidone:

• Frequency not reported: Xanthopsia

Clonidine:

• Frequency not reported: Burning of the eyes, blurred vision^[Ref]

Psychiatric

Chlorthalidone:

• Frequency not reported: Restlessness

Clonidine:

• Common (1% to 10%): Nervousness, agitation, mental depression, loss of libido
• Uncommon (0.1% to 1%): Insomnia
• Frequency not reported: Vivid dreams, nightmares, behavioral changes, restlessness, anxiety, visual and auditory hallucinations, delirium^[Ref]

Renal

Clonidine:

• Frequency not reported: Dryness of the nasal mucosa^[Ref]

Further information

Chlorthalidone/clonidine side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

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