Formulary
Hydrochlorothiazide: Indications, Dosing, Side Effects and Interactions
Hydrochlorothiazide clinical drug profile including indications, dosing, side effects, cautions and interactions.
MedNext Academy | 3 min read
Hydrochlorothiazide: Indications, Dosing, Side Effects and Interactions
Hydrochlorothiazide clinical drug profile including indications, dosing, side effects, cautions and interactions.
Indications and dose
**Indications listed in combination monographs (available in the UK only in combination with other drugs)**
- **Adult** (By Mouth): Doses listed in combination monographs.
Cautions
For all thiazides and related diuretics Diabetes; gout; risk of hypokalaemia; systemic lupus erythematosus Cautions, further information Existing conditions Thiazides and related diuretics can exacerbate diabetes, gout, and systemic lupus erythematosus. Potassium loss Hypokalaemia can occur with thiazides and related diuretics. Hypokalaemia is dangerous in severe cardiovascular disease and in patients also being treated with cardiac glycosides. Often the use of potassium-sparing diuretics avoids the need to take potassium supplements. In hepatic impairment, hypokalaemia caused by diuretics can precipitate encephalopathy. Elderly Lower initial doses of diuretics may be necessary in the elderly because they are particularly susceptible to the side-effects. The dose should then be adjusted according to renal function. M Screening Tool of Older Persons' potentially inappropriate Prescriptions (STOPP) criteria to aid medication reviews (see Prescribing in the elderly for information). Potentially inappropriate: with current significant hypokalaemia (serum potassium less than 3 mmol/L), hyponatraemia (serum sodium less than 130 mmol/L), or hypercalcaemia (corrected serum calcium greater than 2.65 mmol/L)-contra-indicated; hypokalaemia, hyponatraemia, and hypercalcaemia can be precipitated by a thiazide diuretic with a history of gout (gout can be precipitated by a thiazide diuretic)
Contraindications
For all thiazides and related diuretics Addison's disease; hypercalcaemia; hyponatraemia; refractory hypokalaemia; symptomatic hyperuricaemia
Side effects
For all thiazides and related diuretics Common or very common Alkalosis hypochloraemic; constipation; diarrhoea; dizziness; electrolyte imbalance; erectile dysfunction; fatigue; headache; hyperglycaemia; hyperuricaemia; nausea; postural hypotension; skin reactions; vomiting Uncommon Agranulocytosis; aplastic anaemia; leucopenia; pancreatitis; photosensitivity reaction; thrombocytopenia Rare or very rare Paraesthesia Side-effects For hydrochlorothiazide Uncommon Appetite decreased; epigastric discomfort; fever; gastrointestinal spasm; glycosuria; haemolytic anaemia; insomnia; jaundice cholestatic; muscle cramps; nephritis tubulointerstitial; pneumonitis; pulmonary oedema; renal impairment; respiratory distress; sialadenitis; toxic epidermal necrolysis; vasculitis; vision disorders Frequency not known Basal cell carcinoma (particularly in long term use); cutaneous lupus erythematosus; restlessness; squamous cell carcinoma (particularly in long term use)
Interactions
**Severe interactions:**
- Antibacterials : Severe hyponatraemia may occur with concomitant administration of hydrochlorothiazide and trimethoprim.
- Enhanced hypotensive effect, risk of severe hyperkalaemia with potassium-sparing diuretics.
- Sympathomimetics : increased risk of hypokalaemia with thiazide diuretics and high doses of beta 2 sympathomimetics (See 4.4 Warnings and Precautions, use of beta 2 -agonists in severe asthma).
**Other interactions (34):**
- Lithium generally should not be given with diuretics (see 4.3 Contraindications).
- Diuretic agents reduce the renal clearance of lithium and add a high risk of lithium toxicity.
- Refer to the prescribing information for lithium preparations before use of such preparations.
- Analgesics: Some Non-Steroidal Anti-inflammatory Agents (NSAIDs), including selective cyclooxygenase-2 inhibitors (COX-2 inhibitors), may reduce the effect of antihypertensive drugs, including the...
- Diuretics may increase the risk of nephrotoxicity of NSAIDs.
- When amiloride is administered concomitantly with ACE inhibitors, angiotensin II receptor antagonists, trilostane, ciclosporin or tacrolimus, the risk of hyperkalaemia may be increased.
Pregnancy
For all thiazides and related diuretics Thiazides and related diuretics should not be used to treat gestational hypertension. They may cause neonatal thrombocytopenia, bone marrow suppression, jaundice, electrolyte disturbances, and hypoglycaemia; placental perfusion may also be reduced. Stimulation of labour, uterine inertia, and meconium staining have also been reported.
Hepatic impairment
For all thiazides and related diuretics In general, manufacturer advises caution in mild to moderate impairment; avoid in severe impairment.
Renal impairment
For all thiazides and related diuretics In general, manufacturers advise caution in mild to moderate impairment (risk of electrolyte imbalance and reduced renal function); avoid in severe impairment (ineffective if creatinine clearance less than 30 mL/minute). See Prescribing in renal impairment .
Medicinal forms
Medicinal forms No licensed medicines listed.
Clinical governance
**Author:** MedNext Clinical Team. **Clinical reviewer:** Dr Shameer Deen, MBBS, MS, MRCS. **Sources:** BNF, Indian Pharmacopoeia, CIMS India. **Correction:** Report errors at support@mednext.academy.
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