Contains the active ingredient, prazosin hydrochloride
Consumer Medicine Information
NOTICE: This Consumer Medicine Information (CMI) is intended for persons
living in Australia. This page contains answers to some common
. It does
not contain all the information that is known about
. It does not take the
place of talking to your doctor or pharmacist. All medicines have risks
and benefits. Your doctor has weighed the risk of you using this medicine
against the benefits he/she expects it will have for you. If you have
any concerns about using this medicine, ask your doctor or pharmacist.
Bookmark or print this page, you may need to read it again.
What prazosin is used for
The name of your medicine is APO-Prazosin. It contains the active ingredient, prazosin (as prazosin hydrochloride).
It is used to treat:
high blood pressure (hypertension)
prostate problems, such as benign prostatic hyperplasia (BPH) in men waiting for prostate surgery
Raynaud's disease, where the fingers become white and very painful when cold
certain types of heart failure.
How it works
Prazosin works by relaxing the muscles in the walls of blood vessels and making it easier for blood to flow. They also relax
the muscles in the prostate gland and increase the flow of urine.
When use to treat high blood pressure or heart failure, prazosin is often used together with other medicines.
Ask your doctor if you have any questions about why this medicine has been prescribed for you.
Your doctor may have prescribed prazosin for another reason.
This medicine is available only with a doctor's prescription.
There is no known evidence to show that this medicine is addictive.
Use in children
There is not enough information to recommend the use of this medicine in children.
Care when driving
Be careful driving or operating machinery until you know how prazosin affects you.
It may cause dizziness, light-headedness, drowsiness, blurred vision or fainting in some people, especially after the first
dose or a dose increase. Make sure you know how you react to prazosin before you do anything that could be dangerous if you
get the above side effects. If any of these occurs do not drive.
Before you take prazosin
When you must not take it
Do not take this medicine if you have had an allergic reaction to prazosin or to related medicines called quinazolines, or
any of the ingredients listed at the end of this leaflet.
Symptoms of an allergic reaction may include: shortness of breath, wheezing or difficulty breathing; swelling of the face,
lips, tongue, throat or other parts of the body; muscle pain or tenderness or joint pain or rash, itching or hives on the
Do not take this medicine after the expiry date (EXP) printed on the pack.
If you take this medicine after the expiry date has passed, it may not work as well.
Do not take this medicine if the packaging is torn, shows signs of tampering or if it does not look quite right.
If it has expired or is damaged, return it to your pharmacist for disposal.
If you are not sure whether you should start taking this medicine, talk to your doctor or pharmacist.
Before you start to take it
Tell your doctor if:
You have allergies to:
any other medicines
any other substances, such as foods, preservatives or dyes.
You have or have had any medical conditions, especially the following:
heart problems such as heart failure or angina or recent heart attack
kidney or liver problems.
You plan to become pregnant or breast-feed.
Like most medicines, prazosin is not recommended for use during pregnancy or if you are breast-feeding, unless you and your
doctor have discussed the risks and benefits involved
You are planning to have cataract surgery.
If you are taking or have previously taken prazosin then the eye surgeon needs to be aware of this so he can be extra careful
to avoid complications during the operation.
If you have not told your doctor about any of the above, tell them before you start taking this medicine.
Taking other medicines
Tell your doctor or pharmacist if you are taking any other medicines, including any that you buy without a prescription from
your pharmacy, supermarket or health food shop.
Some medicines and prazosin may interfere with each other. These include:
medicines used to lower blood pressure or for other heart conditions
fluid tablets (diuretics), also used to lower blood pressure
medicines to treat impotence (erectile dysfunction).
These medicines may be affected by prazosin or may affect how well it works. You may need different amounts of your medicines,
or you may need to take different medicines.
Your doctor and pharmacist can tell you if you are taking any of these medicines. They may also have more information on medicines
to be careful with or avoid while taking prazosin.
Other interactions not listed above may also occur.
How to take this medicine
Follow all directions given to you by your doctor or pharmacist carefully.
They may be different to the information in this leaflet.
If you do not understand any written instructions, ask your doctor or pharmacist for help.
How much to take
Your doctor or pharmacist will tell you how many tablets you will need to take. This depends on your condition and whether
or not you are taking any other medicines.
Prazosin is usually started at a low dose of 0.5 mg (half a 1mg tablet). Your doctor may gradually increase this dose as
required. Starting with a low dose reduces the risk of too great a drop in your blood pressure which can make you dizzy,
light-headed or faint.
Hypertension (high blood pressure):
The usual starting dose is 0.5 mg twice a day, increasing to 1 mg two or three times a day. Your doctor may increase this
up to 20 mg a day, taken as divided doses.
The usual starting dose is 0.5 mg increasing to 4 mg a day, divided into three or four doses. This may be increased by your
doctor up to 20 mg a day, taken in divided doses.
The usual starting dose is 0.5 mg twice a day. Your doctor may increase this up to 1 mg or 2 mg twice a day.
Benign prostatic hyperplasia (BPH):
The usual starting dose is 0.5 mg twice a day. Your doctor may increase this gradually up to a maximum of 2 mg twice a day.
How to take it
Swallow the tablets with a glass of water.
The tablets can be broken in half, if your doctor has prescribed this.
When to take it
Take it at about the same time each day.
Taking your medicine at the same time each day will have the best effect. It will also help you remember when to take it.
Take your very first dose last thing at night, just before going to bed. Be very careful if you need to get up during the
night, because you may feel dizzy and could fall.
If your doctor increases your dose, take the first of that increased dose last thing at night. Again, be especially careful
if you have to get up in the night.
It does not matter if you take it before, with or after food.
How long to take it for
Prazosin helps control your condition, but does not cure it. Therefore you must take your medicine every day.
If you are taking prazosin for high blood pressure, heart failure or Raynaud's disease, you may need to take it for a long
If you are taking prazosin for prostate problems, you will only have to take it until your operation.
Continue taking your medicine for as long as your doctor tells you.
Make sure you have enough to last over weekends and holidays.
If you forget to take it
If it is almost time for your next dose (within 3 hours), skip the dose you missed and take your next dose when you are meant
Otherwise, take it as soon as you remember, and then go back to taking your medicine as you would normally.
Do not take a double dose to make up for the dose that you missed.
This may increase the chance of you getting an unwanted side effect.
If you miss two doses or more, you will need to restart at a low dose and build up again gradually to your usual dose.
Ask your doctor how to do this.
If you are not sure what to do, ask your doctor or pharmacist.
If you have trouble remembering to take your medicine, ask your pharmacist for some hints.
If you take too much (overdose)
Immediately telephone your doctor or the Poisons Information Centre (Tel: 13 11 26 for Australia) for advice, or go to the
Accident and Emergency Department at the nearest hospital, if you think that you or anyone else may have taken too much prazosin.
Do this even if there are no signs of discomfort or poisoning.
You may need urgent medical attention.
If you take too much prazosin, you may feel lightheaded, dizzy, have a fast or irregular heartbeat, or you may faint.
While you are taking prazosin
Things you must do
Get up slowly after you have been sitting or lying down.
Prazosin can cause dizziness, light-headedness and fainting, particularly if you get up too quickly. This effect is more
likely to occur if you have just started prazosin, if the dose has just been increased or you have started taking another
blood pressure medicine as well.
These symptoms can be dangerous, especially in people aged 65 years or older with heart or blood vessel disease.
If you feel dizzy or light-headed, lie down so that you do not faint, then sit for a few moments before standing to prevent
the dizziness from returning. Make sure the area around you is clear so that you do not injure yourself if you fall.
If these symptoms continue, tell your doctor.
A change in your dose may be needed.
Tell any other doctors, dentists, and pharmacists who are treating you that you are taking prazosin.
If you are about to have eye surgery (for example cataract surgery) tell any doctors or surgeons that you are taking prazosin.
Tell your doctor immediately if you become pregnant.
If you are about to have any blood or urine tests, tell your doctor that you are taking this medicine.
Go to your doctor regularly for a check-up.
Your doctor may occasionally do tests to make sure the medicine is working and to prevent side effects.
Things you must not do
Do not give this medicine to anyone else, even if their symptoms seem similar to yours.
Do not take your medicine to treat any other complaints unless your doctor tells you to.
Do not stop taking your medicine, or change the dosage, without checking with your doctor.
Things to be careful of
Be careful driving or operating machinery until you know how prazosin affects you.
Prazosin may cause dizziness, light-headedness or fainting in some people, especially after the first dose or a dose increase.
Blurred vision or drowsiness may also occur. Make sure you know how you react to prazosin before you drive a car, operate
machinery, or do anything else that could be dangerous if you are dizzy, light-headed or not alert. If this occurs do not
Limit the amount of alcohol you drink while taking prazosin.
Combining prazosin with alcohol can make you more dizzy or light-headed.
Make sure you drink enough water in hot weather, during exercise and when you have to stand for long periods of time, while
you are taking prazosin. This is because dizziness, light-headedness and fainting are more likely to occur in these situations.
If you continue to feel unwell, tell your doctor.
Side effects of prazosin
All medicines may have some unwanted side effects. Sometimes they are serious, but most of the time, they are not. Your doctor
has weighed the risks of using this medicine against the benefits they expect it will have for you.
If you are 65 years or older, you should be especially careful while taking prazosin. Report any side effects promptly to
Tell your doctor or pharmacist as soon as possible if you do not feel well while you are taking prazosin.
Ask your doctor or pharmacist to answer any questions you may have.
Following is a list of possible side effects. Do not be alarmed by this list. You may not experience any of them.
Tell your doctor as soon as possible if you notice any of the following:
sharp pain in the stomach or back
fast or slow heart beat
fainting or passing out
symptoms of an allergic reaction such as: shortness of breath, wheezing or difficulty breathing; swelling of the face, lips,
tongue, throat or other parts of the body; muscle pain or tenderness or joint pain or rash, itching or hives on the skin
hallucinations (seeing, hearing or feeling things that aren't there)
These may be serious side effects. You may need medical attention. Most of these side effects are rare.
Tell your doctor or pharmacist if you notice any of the following and they worry you:
dizziness, spinning sensation or light-headedness when standing up
swelling of the hands, feet or ankles
pounding heart beat
nausea and vomiting
constipation or diarrhoea
feeling sick, vomiting ,dry mouth
weakness, lack of energy
pain or fever
skin problems such as mild rash, itching or hives
blurred vision or painful or red eyes
hair loss or thinning
poor bladder control
painful, continual erection
ringing in the ears (tinnitus)
stuffy nose, nosebleed
shortness of breath
problems getting to sleep, or being excessively sleepy
tingling or numbness in the hands or feet
inflamed blood vessels, often with skin rash
generally feeling unwell.
The above list includes the more common side effects. Mostly, these are mild.
Other side effects not listed above may occur in some patients.
Tell your doctor or pharmacist if you notice anything that is making you feel unwell.
After taking this medicine
Keep your medicine in its original packaging until it is time to take them.
If you take the tablets out of their original packaging they may not keep well.
Keep your medicine in a cool dry place where the temperature will stay below 25°C. Protect it from light.
Do not store your medicine, or any other medicine, in the bathroom or near a sink.
Do not leave it on a window sill or in the car.
Heat and dampness can destroy some medicines.
Keep it where children cannot reach it.
A locked cupboard at least one-and-a-half metres above the ground is a good place to store medicines.
If your doctor or pharmacist tells you to stop taking this medicine or it has passed its expiry date, ask your pharmacist
what to do with any medicine that is left over.
Where to go for further information
Pharmaceutical companies are not in a position to give people an individual diagnosis or medical advice. Your doctor or pharmacist
is the best person to give you advice on the treatment of your condition.
What APO-Prazosin looks like
1 mg tablets:
Capsule-shaped, white, flat-faced, bevelled edge tablets, scored and engraved "APO P1" on one side, the other side plain.
2 mg tablets:
Round, white biconvex tablets, scored and engraved "APO" over "P2" on one side, the other side plain.
5 mg tablets:
Diamond-shaped, white biconvex tablets, scored and engraved "APO" over "P5" on one side, the other side plain.
Each tablet strength is available in a blister pack containing 100 tablets.
Each tablet contains 1 mg, 2 mg or 5 mg of prazosin as the active ingredient.
It also contains the following inactive ingredients:
This medicine is gluten-free, sucrose-free, tartrazine-free and free of other azo dyes.
Australian Registration Numbers
APO-Prazosin 1 mg tablets:
AUST R 73858
APO-Prazosin 2 mg tablets:
AUST R 73862
APO-Prazosin 5 mg tablets:
AUST R 73866
Apotex Pty Ltd
16 Giffnock Avenue
Macquarie Park, NSW 2113
Apotex Pty Ltd is the licensee of the registered trademarks APO and APOTEX from the registered proprietor, Apotex Inc.
This leaflet was prepared in April 2012