RAG rating
Document type
Patient information
Hertfordshire and West Essex ICB
Output type
Pharmacy / Prescribing



Metolazone – Switching Brands

Information for patients

You are being treated with metolazone, a thiazide diuretic (water tablet). Metolazone is used to reduce blood pressure and helps to get rid of the extra fluid that builds up in your body when you have heart or kidney problems.

In recent years metolazone has only been available in the UK as an imported product. A product with the brand name Xaqua® is now licensed and available in the UK. Because Xaqua® has a UK licence it should be prescribed instead of the imported products unless it is unsuitable. Most people will be able to switch to Xaqua® after you have discussed this with your specialist health care professional.

How this change will affect you

From now on, the brand of metolazone that you are taking will be written on your presciptions.

If you have just started taking metolazone tablets you will be prescribed the Xaqua® brand.

If you have been taking another brand of metolazone, the team caring for you will decide if it is appropriate for you to switch to the Xaqua® brand. If you switch, they will monitor the effect that Xaqua® brand has on you and adjust the dose if needed. You may need extra blood tests and checks of your blood pressure and weight when you are switched to Xaqua®.

If you do not switch to Xaqua® your doctor or pharmacist will tell you which brand of metolazone you are taking. Your prescription will be changed so metolazone is prescribed by that brand.

Unless your specialist health care professional tells you otherwise, it is important to always stay on the same brand of metolazone.

Differences between metolazone brands

The amount of active ingredient (metolazone) that reaches your system and has an effect may vary with different brands of metolazone. You may find that one brand of metolazone has a ‘stronger’ or ‘weaker’ effect on you than another brand even if you are taking the same dose.

Different brands of metolazone may have different non-active ingredients. Xaqua® contains lactose. Please let the team caring for you or your pharmacist know if this is a problem for you.

Xaqua® only comes as 5mg tablets. These can be broken in half along the scored line. The imported metolazone brands come as 2.5mg, 5mg, or other strengths of tablets.

Dosing information

Finding the right dose of metolazone for you is important.

If you are starting metolazone, you will start on a low dose of the Xaqua® brand and your dose will be adjusted by your specialist health care professional until you are on the dose that works for you. Finding the right dose may mean that you need to take half a tablet or take the dose on alternate days. Your specialist health care professional or pharmacist will tell you what is the right dose for you.

If you are switching to Xaqua® from an imported metolazone brand, you will usually start on a lower dose of Xaqua® and your dose will be adjusted by your specialist health care professional until you are on the right dose for you. This is because equivalent doses of Xaqua®and other metolazone brands might not have the same effect on you.

Checking your medicines

Because the same dose of different brands of metolazone can affect you differently, it is important to check that you have been given the right brand of metolazone.

Each time you receive your metolazone, check that the brand name on the packaging matches the brand name that was on your prescription. If the brand is not the one you were expecting to be given or if you are not sure, ask your pharmacist or the person who prescribes metolazone for you. It is important that you do not use different brands of metolazone at the same time.

Always read the label on your medicines carefully to make sure you take the right dose for you. This is especially important if you need to break or cut your tablets to get the right dose.

When to ask for advice

Tell the team caring for you if your symptoms are not getting better, or if you:

  • are peeing less
  • experience nausea or vomiting
  • have a dry mouth, muscle pains or cramps, muscle fatigue, chills, blurred vision, or a racing heart
  • feel faint, dizzy or light-headed, breathless, thirsty, restless, weak, drowsy, lethargic, or sick
  • notice that your blood pressure is low if you use your own blood pressure monitor at home
  • gain weight or have worsening swelling of your feet, ankles, legs, hands or arms
  • have any other symptoms that you are concerned about.

Your metolazone dose may need to be adjusted. Do not stop treatment without discussing with your specialist health care professional first.

As with all medicines, if you experience any side effects from your treatment, you should report it to your doctor, nurse or pharmacist. You can also use the Yellow Card app (download from Google Play or Apple App Store) or site to report side effects.

Further advice

Always read the patient information leaflet that comes with your medicine.

If you have further queries about metolazone, please discuss these with a member of your clinical team or pharmacist who can advise you on your treatment.

The NHS site and Patient UK have further information on heart failure, kidney disease and thiazide diuretics.

NHS site:

Patient UK:


Patient information leaflet adopted from ‘Metolazone – Switching Brands, Information for patients’, Welsh Medicines Advice Service, published Feb 2023. This leaflet is based on previous work by the Specialist Pharmacy Service (SPS).

Approved Herts West Essex Area Prescribing Committee, June 2023


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Date approved / updated
June 2023
Review date
The recommendation is based upon the evidence available at the time of publication. This recommendation will be reviewed upon request in the light of new evidence becoming available.
Superseded version