Patient leaflet - Hydrochlorothiazide 12.5 mg tablets
What Hydrochlorothiazide is and what it is used for
Hydrochlorothiazide belongs to a group of medicines called “diuretics”. Diuretics increase the amount of water excreted in the urine.
Hydrochlorothiazide is used in adults to treat: y fluid retention in the tissues causing swelling
(oedema) as a result of heart, liver or kidney disease y high blood pressure (hypertension). In this case it
may be prescribed alone or together with another medicine.
What you need to know before you take Hydrochlorothiazide
Do not take this medicine:
y if you are allergic to hydrochlorothiazide or any
of the other ingredients of this medicine (listed in section 6)
y if you are not able to urinate (you have anuria) y if you have severely impaired kidney function.
Warnings and precautions
Talk to your doctor or pharmacist before taking this medicine:
y if you have a severe kidney or liver disease y if you have renal artery stenosis (narrowing of the
blood vessels supplying both kidneys or a solitary kidney)
y if you have diabetes (high blood sugar level) y if your cholesterol or triglyceride levels are high y if you have had a disease called “lupus
erythematosus” (also called “lupus” or “SLE”) y if you have low levels of potassium in your blood
(with or without symptoms such as muscle weakness, muscle spasms or abnormal heartbeat) y if you have low levels of sodium in your blood (with
or without symptoms such as fatigue, confusion, muscle spasms or cramps)
y if you have raised calcium levels in the blood (with
or without symptoms such as nausea, vomiting, constipation, stomach pain, a frequent urge to urinate, feeling thirsty, muscle weakness or spasms)
y if you suffer from attacks of gout (uric acid crystal
deposits in the joints)
y if you experience pain in the eye or loss of vision
(narrow/closed angle glaucoma). These could be symptoms of fluid accumulation in the vascular layer of the eye (choroidal effusion) or increased pressure in your eye and may occur within hours to weeks after taking this medicine. In the absence of treatment, this can lead to permanent vision disorders
y if you suffer from allergies or asthma
y if you have skin reactions such as rash after
exposure to the sun
y if you are taking any other medication y if you are pregnant or intend to become pregnant y if you have had skin cancer or if you develop an
unexpected skin lesion during the treatment. Treatment with hydrochlorothiazide, particularly long term use with high doses, may increase the risk of some types of skin and lip cancer (non-melanoma skin cancer). Protect your skin from sun exposure and UV rays while taking Hydrochlorothiazide y if you experienced breathing or lung problems
(including inflammation or fluid in the lungs) following hydrochlorothiazide intake in the past. If you develop any severe shortness of breath or difficulty breathing after taking Hydrochlorothiazide, seek medical attention immediately.
Exposure to sunlight or UV booths
If you have had reactions to the sunlight because of this medicine and your doctor decided to continue treatment, you must protect your skin from the sun and must not use UV tanning booths (sunbeds) (see also section 4 for what to do if these side effects occur).
Blood test
Your doctor may ask you to have regular blood tests during treatment to monitor your kidney function and to especially control your blood sodium, potassium, calcium, sugar (glucose) and uric acid levels.
Elderly (65 years and older)
In the treatment of elderly patients, attention should be paid to possible restrictions to kidney function (see section 3).
Other medicines and Hydrochlorothiazide Tell your doctor or pharmacist if you are using, have recently used or might use any other medicines.
Your doctor may need to change the dose and/or take other precautions if you are taking other medicines, especially if you are taking any of the following:
y lithium (a medicine used for mental health
conditions), because its combination with hydrochlorothiazide may cause a lithium overdose y medicines to lower blood pressure or treat heart
disease (e.g. diuretics, ACE inhibitors such as ramipril, angiotensin II antagonists such as valsartan, digoxin and nitrates)
y medicines to treat mental health conditions
such as depression, anxiety, schizophrenia (e.g. antidepressants, anxiolytics, antipsychotics, neuroleptics)
y medicines to treat heart rhythm problems (e.g.
hydroquinidine, disopyramide, amiodarone, dronedarone, sotalol, digoxin)
y medicines used for pain or inflammation, non-
steroidal anti-inflammatory drugs (NSAIDs, e.g. ibuprofen) and aspirin
y carbamazepine or oxcarbamazepine (for the
treatment of epilepsy)
y stimulant laxatives, and other laxatives y corticosteroids
y desmopressin (for diabetes or urinary problems) y chelating resins (substances used mainly to treat
high levels of lipids in the blood)
y domperidone (to stop nausea and vomiting) y medicines to treat malaria (e.g. halofantrine,
lumefantrine)
y medicines to treat allergic reactions (e.g.
mizolastine, mequitazine)
y antibiotics to treat infections (e.g. amphotericin B,
erythromycin, levofloxacin, moxifloxacin, spiramycin)
y iodinated contrast agents (used in imaging studies) y medicines to treat prostate disorders (alfuzosin,
doxazosin, prazosin, silodosin, tamsulosin, terazosin)
y medicines to treat erectile dysfunction y medicines used in Parkinson’s disease (dopamine
agonists, levodopa)
y baclofen (to treat muscle stiffness occurring in
diseases such as multiple sclerosis)
y calcium tablets or other calcium supplements y methadone (to treat addiction to certain
substances)
y medicines to treat some cancers (vandetanib, toremifene)
y vincamine (used to treat neurological disorders related to aging)
y cyclosporin (used following organ transplantation, to treat autoimmune diseases, or severe rheumatic or dermatological diseases).
Hydrochlorothiazide with alcohol
Do not consume alcohol while taking the medicine because it may cause orthostatic hypotension (a sudden fall in blood pressure causing dizziness due to change in position, e.g. standing up).
Pregnancy, breast-feeding and fertility If you are pregnant or breast-feeding, think you may be pregnant or are planning to have a baby, ask your doctor or pharmacist for advice before taking this medicine.
Pregnancy
In general, your doctor will advise you to take another medicine instead of Hydrochlorothiazide because it is not recommended during pregnancy, except in rare cases where no other treatment can be used.
This medicine crosses the placenta and its use after the third month of pregnancy may cause serious harm to your baby.
Breast-feeding
Hydrochlorothiazide passes into the breast milk. Do not take this medicine while you are breast-feeding unless advised by your doctor.
Driving and using machines
Hydrochlorothiazide tablets have a minor or moderate influence on the ability to drive and use machines.
Even when used as directed, this medicine may affect your reactions. Thus your ability to drive or operate machinery or work in locations without a solid support may be impaired.
This is especially true at the beginning of treatment, when the dose is increased, the medication is changed or when taken in combination with alcohol.
Anti-doping test
Hydrochlorothiazide could produce a positive analytical result in an anti-doping test.
Hydrochlorothiazide contains lactose
If you have been told by your doctor that you have an intolerance to some sugars, contact your doctor before using this medicine.
How to take Hydrochlorothiazide
Always take this medicine exactly as your doctor has told you. Check with your doctor or pharmacist if you are not sure.
Hydrochlorothiazide tablets are available in 2 strengths: 12.5mg and 25mg tablets.
Oedemas:
The usual starting dose is 50mg to 100mg hydrochlorothiazide a day.
The maintenance dose is usually 25mg to 50mg hydrochlorothiazide a day.
High blood pressure (hypertension):
The recommended starting dose is 12.5mg of 25mg hydrochlorothiazide a day.
Elderly:
In the treatment of elderly patients (65 years and older), attention should be paid to possible restrictions to kidney function.
Use in children and adolescents
There is no experience in children and adolescents. Therefore, hydrochlorothiazide should not be administered to children and adolescents.
Method of administration
For oral use.
Swallow the tablets with a sufficient amount of liquid.
This medicine can be taken with or without food.
The 25mg tablet can be divided into equal doses.
Frequency of administration
This drug has a diuretic effect (i.e. you will urinate more often). Given this, it is best not to take the last dose late in the day in order to avoid waking up during the night.
If you take your tablets in one dose, take them in the morning.
Duration of treatment
Your doctor will tell you how long you should take this medicine.
Your doctor will make regular checks to ensure that the treatment is having the expected effects.
If you have any questions about the duration of treatment, talk to your doctor or pharmacist.
If you take more Hydrochlorothiazide than you should
Contact your doctor or go to the hospital emergency department immediately if you experience nausea, drowsiness, muscle contractions, cardiac arrhythmias (irregular heartbeat), low blood pressure (recognisable by dizziness), confusion or urinary problems.
If you forget to take Hydrochlorothiazide If you forget to take a dose, you should take it as soon as you remember. Do not take a double dose to make up for a forgotten dose but continue treatment as prescribed.
If you stop taking Hydrochlorothiazide
Do not stop treatment with Hydrochlorothiazide unless your doctor tells you to. If you stop treatment your blood pressure will not be controlled (see also Duration of treatment).
If you have any further questions on the use of this medicine, ask your doctor or pharmacist.
Possible side effects
Like all medicines, this medicine can cause side effects, although not everybody gets them.
Effects requiring discontinuation of treatment: You must stop treatment and consult a doctor or hospital emergency department if you have a reaction to sunlight (skin reaction).
Very Common (may affect more than 1 in 10 people): y an increase in blood lipids (hyperlipidaemia) y a decrease in blood potassium levels
(hypokalaemia).
Common (may affect up to 1 in 10 people): y itchy rash (urticaria) and other skin eruptions y loss of appetite, nausea, vomiting, diarrhoea y drop in blood pressure when moving from a lying to a standing position
y inability to achieve or maintain an erection
(impotence)
y decrease in levels of magnesium in the blood
(hypomagnesemia)
y decrease in levels of sodium levels in the blood
(hyponatremia)
y increase in uric acid in the blood (hyperuricemia).
Uncommon (may affect up to 1 in 100 people): y acute renal failure (severely decreased urine flow).
Rare (may affect up to 1 to 1,000 people): y worsening of diabetes
y increased sensitivity to sunlight
y abdominal discomfort, constipation
y liver disorder which can be accompanied by a yellowing of the eyes and skin
y irregular heartbeat
y headache
y dizziness with spinning sensation
y sleep disorders
y feeling sad (depression)
y tingling or numbness of the hands or feet
(paraesthesia)
y vision problems
y increased sugar levels in the blood
y sugar in the urine
y increased calcium levels in the blood
(hypercalcemia)
y low level of platelets in the blood, sometimes with bleeding or bruising under the skin (thrombocytopenia).
Very rare (may affect up to 1 in 10,000 people): y face rash, joint pain, muscle problems, fever (lupus erythematosus)
y inflammation of blood vessels with symptoms such as rash, purplish red marks on the skin, fever (necrotising vasculitis)
y severe skin reaction causing a rash, redness of the skin, blistering of the lips, eyes or mouth, skin peeling, fever (toxic epidermal necrolysis) y allergic reaction (hypersensitivity reaction) y severe abdominal pain (pancreatitis)
y difficulty breathing with fever, coughing, wheezing, breathlessness (respiratory distress including pneumonitis and pulmonary oedema) y acute respiratory distress (signs include severe shortness of breath, fever, weakness, and confusion) y bone marrow depression resulting in a reduction in number of red blood cells, and/or an abnormally low level of white blood cells and platelets y destruction of red blood cells causing paleness, tiredness, breathlessness, dark urine (haemolytic anaemia)
y lack of or low level of white blood cells may cause fever, sore throat or mouth sores, more frequent infections (leukopenia or possible signs of agranulocytosis)
y disturbance of acid-base balance causing
confusion, fatigue, muscle contractions and spasms, rapid breathing (hypochloremic alkalosis).
Not known (frequency cannot be estimated from the available data):
y inadequate production of different blood cells by the bone marrow (myelosuppression)
y significant decrease in urine output (possible signs of kidney problems)
y severe skin disease causing a rash, skin redness, blistering of the lips, eyes or mouth, skin peeling, fever (erythema multiforme)
y fever
y muscle spasms
y weakness (asthenia)
y decreased vision or eye pain due to high ocular pressure (possible signs of fluid accumulation in the vascular layer of the eye (choroidal effusion) or acute angle-closure glaucoma)
y skin and lip cancer (non-melanoma skin cancer).
Reporting of side effects
If you get any side effects, talk to your doctor, pharmacist or nurse. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the Yellow Card Scheme at: www.mhra.gov. uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store. By reporting side effects you can help provide more information on the safety of this medicine.
How to store Hydrochlorothiazide
Keep this medicine out of the sight and reach of children.
Do not use this medicine after the expiry date which is stated on the label after EXP. The expiry date refers to the last day of that month.
This medicinal product does not require any special temperature storage conditions. Store in the original package in order to protect from light.
Do not throw away any medicines via wastewater or household waste. Ask your pharmacist how to throw away medicines you no longer use. These measures will help protect the environment.
Contents of the pack and other information
What Hydrochlorothiazide contains
The active substance is hydrochlorothiazide. Each tablet contains 12.5mg or 25mg of
hydrochlorothiazide.
- The other ingredients are: lactose monohydrate, maize starch, talc, colloidal anhydrous silica and magnesium stearate.
What Hydrochlorothiazide looks like and contents of the pack
Hydrochlorothiazide 12.5mg tablets are white, round and biconvex with a diameter of 5.8 to 6.2mm and a thickness of 3.0 to 3.6mm.
Hydrochlorothiazide 25mg tablets are white, round, flat tablets diameter of 7.8 to 8.2mm and a thickness of 2.7 to 3.4mm and with a scoreline on one side.
The 25mg tablet can be divided into equal doses.
A pack contains 20, 30, 50 or 100 tablets.
Not all pack sizes may be marketed.
Marketing Authorisation Holder
Aspire Pharma Limited
Unit 4, Rotherbrook Court
Bedford Road
Petersfield
GU32 3QG
United Kingdom
Manufacturer
Zakłady Farmaceutyczne POLPHARMA S.A. ul. Pelplińska 19
83-200 Starogard Gdański
POLAND
This leaflet was last revised in June 2026.
1010746 - P1.5
Product name: Hydroxychlorothiazide 12.5mg & 25mg tablets Size: x100
PL/PA no: PL35533/0304-0305
Date of revision: 29.5.26
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