Slow-K® 600mg – patient leaflet, side effects, dosage

1. What Slow-K is and what it is used for

Slow-K belongs to a group of medicines called potassium supplements.

Slow-K contains potassium and is used to treat or prevent low levels of potassium in your body. Slow-K tablets are prolonged-release tablets which means that the potassium is released slowly from the tablet.

Whilst on this medicine your doctor will want to measure the potassium levels in your blood on a regular basis.

2. What you need to know before you take Slow-K

Do not take Slow-K:

• if you are allergic to potassium chloride or any of the other ingredients of this medicine (listed in section 6)
• if you are allergic to potassium intake due to a genetic disorder such as congenital paramyotonia
• if you have been told by your doctor that you have kidney failure
• if you have Addison’s disease (which is a condition where your adrenal gland is not producing enough steroids)
• if you have recently suffered from severe burns
• if you suffer from digestive problems or have difficulty swallowing (due to a narrowing or blockage of your gullet (food pipe) or intestines)
• if you have been told you have metabolic acidosis (a condition caused by increased acid levels in the blood)
• if you are dehydrated (you may feel thirsty with a dry mouth)
• if you have high blood potassium levels (which can cause an abnormal heartbeat)
• if you suffer from a condition called hyporeninaemic hypoaldosteronism (where your body has low levels of an enzyme called renin and a hormone called aldosterone which normally helps to control your blood pressure)
• if you are taking certain types of diuretics (water tablets); either potassium-sparing diuretics (e.g. triamterene and amiloride) or aldosterone antagonists (e.g. spironolactone and eplerenone).

Warnings and precautions

Talk to your doctor or pharmacist before taking Slow-K if you:

• have a stoma or have had any of your bowel removed
• suffer from any condition which affects your bowel movements
• suffer from heart disease (which may cause chest pain, shortness of breath or ankle swelling)
• suffer from kidney problems
• currently have or have previously had a stomach ulcer.

Slow-K is not recommended for use in children.

If any of the above applies to you, or if you are not sure, speak to your doctor or pharmacist before you take Slow-K.

Other medicines and Slow-K

Tell your doctor or pharmacist if you are taking, have recently taken or might take any other medicines.

In particular, tell your doctor or pharmacist if you are taking:

• Potassium-sparing diuretics such as –

  triamterene and amiloride

• Aldosterone antagonists such as –

  spironolactone and eplerenone

If you are taking potassium-sparing diuretics or aldosterone antagonists, stop taking Slow-K. See also the section ‘Do not take Slow-K’.

Tell your doctor or pharmacist if you are taking any of the following as they may increase the risk of high blood potassium levels:

• ACE inhibitors or beta blockers –

  such as captopril or atenolol

• Angiotensin-II-receptor antagonists –

  such as losartan or valsartan

• Ciclosporin –

• Non-steroidal anti-inflammatory –

  medicines (NSAIDs) such as aspirin

  or naproxen

• Heparin –
• Digoxin –

• Direct renin inhibitors –

  such as aliskerin

• Proton pump inhibitors –

Tell your doctor or pharmacist if you are taking anticholinergics such as atropine sulfate or hyoscine butylbromide for stomach spasms or cramps as they can slow down gastrointestinal transit.

Pregnancy and breast-feeding

Your doctor will only give you Slow-K if you really need it. Slow-K is a prolonged-release tablet which means it takes a long time to dissolve. When you are pregnant your digestive system works more slowly and so Slow-K tablets will take longer to pass through your system. This could mean you do not receive the correct amount of potassium from your Slow-K tablets.

Slow-K should not be taken whilst breast-feeding unless your doctor considers that the benefits for you are greater than the risks to the child.

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.

Slow-K contains sucrose

If you have been told by your doctor that you have an intolerance to some sugars, contact your doctor before taking this medicinal product.

This medicine contains less than 1 mmol sodium (23 mg) per tablet, that is to say essentially ‘sodium-free’.

3. How to take Slow-K

Always take this medicine exactly as described in this leaflet or as your doctor has told you. Check with your doctor or pharmacist if you are not sure.

The recommended dose is 2 to 3 tablets a day. Your doctor will decide when and how to treat you with Slow-K. Your doctor may tell you to take up to 12 tablets a day.

• The tablets should not all be taken at once but spread out during the day.

• Take your tablets with fluid during a meal and whilst sitting upright.

• Swallow them whole.
• Do not break or chew them. This is important as the tablets release potassium slowly. If you chew the tablets, this could damage the tablet and let the potassium out too quickly and this could cause stomach problems.

If you take more Slow-K than you should, you may get stomach ache and feel or be sick. In more severe cases you may suffer from low blood pressure, shock, heart problems and convulsions. If you accidentally take too many tablets, or someone else takes your medicine, you should tell your doctor at once or contact your nearest accident and emergency department. Take this leaflet and / or the container with you so the doctor will know what has been taken.

If you forget to take Slow-K, take it as soon as possible, unless it is almost time to take the next dose and then go on as before. Do not take a double dose to make up for a forgotten dose.

If you have any further questions on the use of this medicine, ask your doctor or pharmacist.

4. Possible side effects

Like all medicines, this medicine can cause side effects, although not everybody gets them.

Serious side effects

If you experience any of the following side effects, contact your doctor or pharmacist IMMEDIATELY:

• Signs of intestinal bleeding or ulcers such as coughing up blood (however small the amount), blood in your vomit and black stools
• Severe sickness (feeling or being sick)
• Constipation and / or wind
• Swelling of the stomach
• Diarrhoea
• Severe stomach pains.

Other side effects:

• High blood levels of potassium (which can cause an abnormal heartbeat)
• Itching and skin rashes (nettle rash).

Reporting of side effects

If you get any side effects, talk to your doctor or pharmacist. This includes any possible side effects not listed in this leaflet. You can also report side effects directly via the internet 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.

5. How to store Slow-K

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 tablet container after EXP. The expiry date refers to the last day of that month.

Do not store above 30°C. Keep the tablet container tightly closed in order to protect from moisture.

Do not use this medicine if you notice the appearance has changed in any way.

If your doctor decides to stop your treatment, return any unused medicine to the pharmacist. Only keep it if your doctor tells you to.

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.

6. Contents of the pack and other information

What Slow-K contains:

The active substance is potassium chloride.

The other ingredients are cetostearyl alcohol, gelatin, magnesium stearate, acacia, titanium dioxide (E171), talc, sucrose, red and yellow iron oxides (E172) and carnauba wax.

What Slow-K looks like and contents of the pack

Slow-K is a pale orange, round tablet. They are prolonged-release tablets with a sugar-coating.

Slow-K comes in polypropylene containers with polyethylene caps containing 100 tablets.

Marketing Authorisation Holder

ALTURiX Ltd

287 Upper Fourth Street

Milton Keynes

MK9 1EH

This leaflet was last revised in April 2023

“water tablets” for high blood pressure and certain heart diseases

“water tablets” for heart failure and certain liver and kidney problems

for high blood pressure or heart problems

for treatment of high blood pressure, kidney damage due to diabetes and congestive heart failure

for transplants, rheumatic disease or skin complaints

for pain relief or rheumatism

used to thin the blood

for an irregular heartbeat

for high blood pressure

for indigestion

Manufacturer

Novartis Pharmaceuticals UK Ltd Horsham

West Sussex

RH12 5AB

Manufacturer

Elara Pharmaservices Limited 5 Garden Court

Lockington Hall

Main Street

Lockington

Derby

DE74 2RH

This leaflet was last revised in July 2026

1.42 mm

Times 9pt

VAG Rounded Light 8 pt

Linespacing 9 pt