Sounds like 'dox-AZE-oh-sin'

Key points about doxazosin

  • Doxazosin is used to treat symptoms of an enlarged prostate.
  • Doxazosin is also used for other conditions such as high blood pressure, but this is less common.
  • Find out how to take it safely and possible side effects.
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  • Doxazosin is used to treat symptoms of an enlarged prostate such as difficulty in beginning the flow of urine, weak urine flow and the need to urinate frequently or urgently (including during the middle of the night).
  • It works by relaxing the muscles in the prostate and part of the bladder. It does not make the prostate smaller. 
  • Doxazosin is also used for other conditions such as high blood pressure, but this is less common. 
  • Doxazosin is available as tablets.

  • The starting dose of doxazosin is 1 milligram once a day.  
  • Your doctor will increase your dose slowly over a few weeks to 4 milligrams once a day. This allows your body to get used to the medicine.
  • Always take your doxazosin exactly as your doctor has told you. The pharmacy label on your medicine will tell you how much doxazosin to take, how often to take it and any special instructions.

  • Timing: Take doxazosin with a glass of water at the same time each day. Doxazosin can cause dizziness and fainting, especially after the first dose. Take this dose at bedtime (see dizziness and fainting below). You can take doxazosin with or without food.
  • Limit alcohol while you are taking doxazosin. Alcohol can increase the chance of side effects such as feeling dizzy or faint.
  • Missed dose: If you forget your dose, take it as soon as you remember that day. But, if it is nearly time for your next dose, just take the next dose at the right time. Do not take double the dose.

Like all medicines, doxazosin can cause side effects, although not everyone gets them. Often side effects improve as your body gets used to the new medicine.

Dizziness and fainting

Your first dose of doxazosin may make you feel faint, dizzy or light-headed for a few hours after taking it. To minimise the impact of this effect:

  • Take this dose at bedtime.
  • Be careful when moving from a sitting or lying position, as you are at risk of falls.
  • Stand up slowly from a sitting or lying position.
  • If you feel dizzy or faint, remain lying down until these symptoms have gone.
  • Do not drive or use tools or machines until you know how this medicine affects you.

You should also limit or avoid alcohol while you are taking doxazosin – alcohol increases your chance of having side effects.

Other side effects

Side effects What should I do?
  • Headache
  • Try paracetamol. Check that this can be taken with any other medicines you may take.
  • Tell your doctor if troublesome.
  • Swollen feet or ankles
  • When you sit down, rest your legs on a low stool.
  • Tell your doctor if troublesome.
  • Changes in your heart beat (a pounding or racing feeling)
  • Chest pain 
  • Tell your doctor immediately or ring HealthLine.
Did you know that you can report a side effect to a medicine to CARM (Centre for Adverse Reactions Monitoring)? Report a side effect to a product(external link)

Doxazosin may interact with a few medications and herbal supplements, so check with your doctor or pharmacist before starting doxazosin or before starting any new medicines.

The following links provide further information on doxazosin. Be aware that websites from other countries may contain information that differs from New Zealand recommendations.

Doxazosin(external link) New Zealand Formulary
Apo-Doxazosin(external link) Medsafe Consumer Information Sheet (NZ)
Doxazosin(external link) Patient Info, UK

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Credits: Sandra Ponen, Pharmacist. Healthify is brought to you by Health Navigator Charitable Trust.

Reviewed by: Nicola Rowbottom, Pharmacist, South Canterbury

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