Hydrochlorothiazide 12.5mg Tablets
Overview
What is this medicine?
How to Use This Medicine
To get the most benefit from your medication, it's essential to follow your doctor's instructions carefully. Read all the information provided with your medication and follow the instructions closely.
Continuing Your Medication
Continue taking your medication as directed by your doctor or healthcare provider, even if you're feeling well. This medication may increase the frequency of urination, so try to avoid taking it too close to bedtime to minimize sleep disturbances.
Oral Suspension Instructions
You can take the oral suspension with or without food. Before using, shake the suspension well to ensure the medication is evenly mixed. To measure the correct dose, use the measuring device provided with the medication. If one is not included, ask your pharmacist for a suitable measuring device.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication:
Store it at room temperature, protected from light
Keep it in a dry place, away from the bathroom
* Ensure the lid is tightly closed
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
Lifestyle & Tips
- Take the medication exactly as prescribed, usually once daily in the morning to avoid nighttime urination.
- Do not stop taking the medication without consulting your doctor, even if you feel well.
- Maintain a balanced diet, and discuss appropriate salt intake with your doctor.
- Stay hydrated, especially in hot weather or during exercise, but avoid excessive fluid intake unless advised by your doctor.
- Limit alcohol consumption, as it can increase the risk of dizziness and low blood pressure.
- Protect yourself from the sun (wear protective clothing, use sunscreen) as this medication can increase sun sensitivity.
- Regularly monitor your blood pressure at home if advised by your doctor.
Available Forms & Alternatives
Dosing & Administration
Adult Dosing
Condition-Specific Dosing:
Pediatric Dosing
Dose Adjustments
Renal Impairment:
Hepatic Impairment:
Pharmacology
Mechanism of Action
Pharmacokinetics
Absorption:
Distribution:
Elimination:
Pharmacodynamics
Safety & Warnings
Side Effects
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction: rash, hives, itching, red, swollen, blistered, or peeling skin (with or without fever), wheezing, tightness in the chest or throat, trouble breathing, swallowing, or talking, unusual hoarseness, or swelling of the mouth, face, lips, tongue, or throat.
Signs of high blood sugar: confusion, feeling sleepy, unusual thirst or hunger, frequent urination, flushing, rapid breathing, or fruity-smelling breath.
Signs of fluid and electrolyte problems: mood changes, confusion, muscle pain or weakness, irregular or rapid heartbeat, severe dizziness or fainting, increased thirst, seizures, feeling extremely tired or weak, decreased appetite, difficulty urinating or changes in urine output, dry mouth, dry eyes, or severe nausea and vomiting.
Signs of pancreatitis (pancreas problem): severe abdominal pain, severe back pain, or severe nausea and vomiting.
Signs of kidney problems: difficulty urinating, changes in urine output, blood in the urine, or sudden weight gain. Additionally, dark urine or yellowing of the skin and eyes may occur.
Fever, chills, or sore throat; unexplained bruising or bleeding; or feeling extremely tired or weak.
Abnormal sensations such as burning, numbness, or tingling.
Shortness of breath.
Restlessness.
Difficulty achieving or maintaining an erection.
Eye Problems:
This medication can cause certain eye problems, which may lead to permanent vision loss if left untreated. If you experience eye problems, symptoms such as changes in vision or eye pain typically occur within hours to weeks of starting this medication. Contact your doctor immediately if you notice any of these signs.
Skin Cancer Risk:
Rarely, people taking hydrochlorothiazide have developed certain types of skin cancer. To minimize this risk, protect your skin from the sun and follow your doctor's recommendations for skin checks. If you notice any changes in the color or size of a mole, or any new or changing skin lump or growth, contact your doctor right away.
Other Side Effects:
Most people do not experience significant side effects, but some may occur. If you are bothered by any of the following side effects or if they persist, contact your doctor or seek medical attention:
Constipation, diarrhea, upset stomach, vomiting, or decreased appetite.
Stomach cramps.
Dizziness, tiredness, or weakness.
Headache.
This is not an exhaustive list of possible side effects. If you have questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Severe dizziness or fainting
- Extreme thirst or very dry mouth
- Muscle cramps, weakness, or spasms
- Nausea or vomiting that doesn't go away
- Unusual tiredness or confusion
- Irregular or fast heartbeat
- Decreased urination or no urination
- Yellowing of the skin or eyes (jaundice)
- Severe skin rash or blistering after sun exposure
Before Using This Medicine
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Describe the allergic reaction you experienced, including the symptoms that occurred.
A known sulfa allergy.
Difficulty urinating or inability to pass urine.
Current use of dofetilide or lithium.
This list is not exhaustive, and it is crucial to discuss all your medications, including prescription and over-the-counter drugs, natural products, and vitamins, with your doctor and pharmacist. They will help determine if it is safe to take this medication with your existing treatments and health conditions.
Remember, do not start, stop, or change the dosage of any medication without first consulting your doctor to ensure your safety.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
Caution with Daily Activities
Until you know how this medication affects you, avoid driving and other activities that require you to be alert. To minimize the risk of dizziness or fainting, get up slowly from a sitting or lying position, and be cautious when climbing stairs.
Monitoring and Lab Tests
Follow your doctor's instructions for regular blood work and other laboratory tests. This medication can cause increased cholesterol and triglyceride levels. If you have high cholesterol or triglycerides, discuss this with your doctor. Additionally, if you have diabetes, you will need to closely monitor your blood sugar levels. Check your blood pressure as directed by your doctor.
Interactions with Other Medications and Substances
This medication may affect certain laboratory test results. Inform all your healthcare providers and laboratory personnel that you are taking this medication. If you have high blood pressure, consult your doctor before using over-the-counter (OTC) products that may increase blood pressure, such as cough or cold medications, diet pills, stimulants, non-steroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen, and certain natural products or aids.
Diuretic Effects
This medication is a potent diuretic, which can lead to excessive loss of water and electrolytes (such as potassium) in the blood. This can cause severe health problems. Your doctor will closely monitor you to adjust the dosage according to your body's needs.
Dietary Considerations
If you are on a low-salt or salt-free diet, discuss this with your doctor. Also, consult your doctor before consuming alcohol, marijuana, or other forms of cannabis, or taking prescription or OTC medications that may cause drowsiness.
Dehydration and Low Blood Pressure
Inform your doctor if you experience excessive sweating, fluid loss, vomiting, or diarrhea, as these can lead to low blood pressure.
Interactions with Other Medications
If you take cholestyramine or colestipol, consult your pharmacist about how to take these medications with this drug. Be aware of the risk of gout attacks.
Lupus and Sun Sensitivity
If you have lupus, this medication can cause your condition to become active or worsen. Report any new or worsening symptoms to your doctor immediately. This medication can also increase your risk of sunburn. Take precautions when exposed to the sun, and inform your doctor if you experience sunburn easily while taking this medication.
Age-Related Precautions
If you are 65 or older, use this medication with caution, as you may be more susceptible to side effects.
Pregnancy and Breastfeeding
Inform your doctor if you are pregnant, plan to become pregnant, or are breastfeeding. You will need to discuss the benefits and risks of this medication to you and your baby.
Overdose Information
Overdose Symptoms:
- Dehydration
- Electrolyte depletion (e.g., hypokalemia, hyponatremia)
- Hypotension (low blood pressure)
- Dizziness, weakness, confusion
- Nausea, vomiting
- Cardiac arrhythmias (due to electrolyte imbalance)
What to Do:
Seek immediate medical attention. Call 911 or Poison Control at 1-800-222-1222. Treatment is supportive and symptomatic, focusing on fluid and electrolyte replacement.
Drug Interactions
Contraindicated Interactions
- Anuria
- Hypersensitivity to hydrochlorothiazide or other sulfonamide-derived drugs
Major Interactions
- Lithium (increased lithium toxicity due to reduced renal clearance)
- Nonsteroidal Anti-inflammatory Drugs (NSAIDs) (may reduce diuretic, natriuretic, and antihypertensive effects of thiazides)
- Digoxin (increased risk of digitalis toxicity due to hypokalemia)
- Corticosteroids, ACTH (increased risk of hypokalemia)
- Other antihypertensives (additive hypotensive effects)
- Cholestyramine, Colestipol (may reduce absorption of hydrochlorothiazide)
Moderate Interactions
- Antidiabetic agents (insulin, oral hypoglycemics) (may decrease hypoglycemic effect, requiring dosage adjustment)
- Skeletal muscle relaxants, nondepolarizing (e.g., tubocurarine) (may enhance muscle relaxant effect)
- Pressor amines (e.g., norepinephrine) (possible decreased arterial responsiveness)
- Alcohol, barbiturates, narcotics (may potentiate orthostatic hypotension)
Minor Interactions
- Not available
Monitoring
Baseline Monitoring
Rationale: To establish baseline levels and identify pre-existing imbalances, as HCTZ can cause electrolyte disturbances.
Timing: Prior to initiation of therapy.
Rationale: To assess kidney function, as HCTZ efficacy is reduced in severe renal impairment and to guide dosing.
Timing: Prior to initiation of therapy.
Rationale: To establish baseline and guide therapy for hypertension.
Timing: Prior to initiation of therapy.
Rationale: To establish baseline, as HCTZ can increase uric acid levels.
Timing: Prior to initiation of therapy.
Rationale: To establish baseline, as HCTZ can affect glucose tolerance.
Timing: Prior to initiation of therapy.
Routine Monitoring
Frequency: Periodically, especially during initial therapy, dose adjustments, and in patients at higher risk (e.g., elderly, those on other interacting drugs). Typically every 1-3 months initially, then every 6-12 months.
Target: Potassium: 3.5-5.0 mEq/L; Sodium: 135-145 mEq/L; Magnesium: 1.7-2.2 mg/dL; Calcium: 8.5-10.2 mg/dL
Action Threshold: Potassium < 3.0 mEq/L (consider supplementation or dose adjustment); Sodium < 130 mEq/L (investigate cause, consider discontinuation); Significant deviations from normal ranges.
Frequency: Periodically, especially in patients with pre-existing renal impairment or those on other nephrotoxic drugs. Typically every 6-12 months.
Target: Within normal limits for age/sex.
Action Threshold: Significant increase in BUN/Creatinine (e.g., >20-30% from baseline) or eGFR < 30 mL/min (consider discontinuation or switch to loop diuretic).
Frequency: Regularly, as per hypertension guidelines (e.g., monthly until controlled, then every 3-6 months).
Target: Individualized, typically <130/80 mmHg for most adults.
Action Threshold: Failure to achieve target BP, or symptomatic hypotension.
Frequency: Periodically, especially in patients with history of gout or hyperuricemia. Typically every 6-12 months.
Target: Within normal limits.
Action Threshold: Symptomatic hyperuricemia or gout flares.
Frequency: Periodically, especially in diabetic patients or those at risk for diabetes. Typically every 6-12 months.
Target: Individualized, based on diabetes management goals.
Action Threshold: Significant hyperglycemia.
Symptom Monitoring
- Dizziness or lightheadedness (especially upon standing)
- Excessive thirst or dry mouth
- Muscle cramps or weakness
- Nausea or vomiting
- Unusual fatigue or lethargy
- Irregular heartbeat
- Signs of dehydration (e.g., decreased urination, sunken eyes)
- Skin rash or increased sensitivity to sunlight (photosensitivity)
Special Patient Groups
Pregnancy
Generally not recommended for routine use in pregnancy, especially for uncomplicated hypertension, due to potential for fetal/neonatal adverse effects (e.g., fetal or neonatal jaundice, thrombocytopenia, other adverse reactions seen in adults). Category D for pregnancy-induced hypertension or edema. Use only if clearly needed and the potential benefit outweighs the potential risk to the fetus.
Trimester-Specific Risks:
Lactation
Excreted in human milk. Use with caution. Potential for adverse effects in the nursing infant (e.g., dehydration, electrolyte imbalance, jaundice). May also suppress lactation. Consider alternative agents, especially in preterm infants or during the first month postpartum.
Pediatric Use
Dosing exists for children, but careful monitoring of fluid and electrolyte balance is crucial. Pediatric patients may be more susceptible to electrolyte disturbances. Not recommended for neonates or infants for hypertension.
Geriatric Use
Elderly patients may be more sensitive to the effects of hydrochlorothiazide, particularly regarding electrolyte imbalances (hypokalemia, hyponatremia) and orthostatic hypotension. Initiate therapy with lower doses and monitor closely.
Clinical Information
Clinical Pearls
- Hydrochlorothiazide is a common first-line agent for hypertension, often used alone or in combination with other antihypertensives.
- Take in the morning to avoid nocturia (nighttime urination).
- Monitor serum potassium, sodium, magnesium, and calcium levels regularly, especially during initiation and dose changes.
- Advise patients about photosensitivity and the importance of sun protection.
- May increase uric acid levels and precipitate gout attacks in susceptible individuals.
- Can cause hyperglycemia, particularly in patients with pre-diabetes or diabetes.
- Less effective in patients with significant renal impairment (CrCl < 30 mL/min).
Alternative Therapies
- Other thiazide diuretics (e.g., Chlorthalidone, Indapamide)
- Loop diuretics (e.g., Furosemide, Torsemide) for more potent diuresis or in renal impairment
- Potassium-sparing diuretics (e.g., Spironolactone, Amiloride)
- ACE inhibitors (e.g., Lisinopril, Ramipril)
- Angiotensin Receptor Blockers (ARBs) (e.g., Valsartan, Losartan)
- Calcium Channel Blockers (e.g., Amlodipine, Diltiazem)
- Beta-blockers (e.g., Metoprolol, Atenolol)
- Alpha-blockers (e.g., Doxazosin, Prazosin)