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 this medicine is used for
The name of your medicine is Chemmart 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.
Ask your doctor if you have any questions about why this medicine has been prescribed for you. Your doctor may have prescribed
this medicine for another reason.
This medicine is available only with a doctor's prescription
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.
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 occur do not drive.
Before you take this medicine
When you must not take it
Do not take this medicine if:
You are hypersensitive to, or 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: cough, shortness of breath, wheezing or difficulty breathing; swelling of the
face, lips, tongue, throat or other parts of the body; rash, itching or hives on the skin; fainting; or hay fever-like symptoms.
If you think you are having an allergic reaction, do not take any more of the medicine and contact your doctor immediately
or go to the Accident and Emergency department at the nearest hospital.
The expiry date (EXP) printed on the pack has passed.
The packaging is torn, shows signs of tampering or it does not look quite right.
Before you start to take it
Before you start taking this medicine, 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 are currently pregnant or plan to become pregnant.
Do not take this medicine whilst pregnant until you and your doctor have discussed the risks and benefits involved.
You are currently breastfeeding or plan to breastfeed.
Prazosin may appear in breast milk. Do not take this medicine whilst breastfeeding until 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.
You are planning to have surgery or an anaesthetic.
You are currently receiving or are planning to receive dental treatment.
You are taking or are planning to take any other medicines. This includes vitamins and supplements that are available from
your pharmacy, supermarket or health food shop.
Taking other medicines
Some medicines may interact with prazosin. 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).
If you are taking any of these you may need a different dose 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 medicines not listed above may also interact with prazosin.
How to take this medicine
Follow carefully all directions given to you by your doctor.
Their instructions may be different to the information in this leaflet.
How much to take
Your doctor will tell you how much of this medicine you should take. This will depend on your condition and whether you are
taking any other medicines.
Do not stop taking your medicine or change your dosage without first checking with your doctor,
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 this medicine at the same time each day. Taking this medicine at the same time each day will have the best effect and
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 missed doses.
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 to help you remember.
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 this medicine
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.
See your doctor immediately if you experience painful erections or if your erection continues for longer than four hours.
Tell your doctor that you are taking this medicine if:
you are about to be started on any new medicine
you are pregnant or are planning to become pregnant
you are breastfeeding or are planning to breast-feed
you are about to have any blood tests or urine tests
you are going to have surgery or an anaesthetic or are going into hospital. You are about to have eye surgery (for example
Your doctor may occasionally do tests to make sure the medicine is working and to prevent side effects.
Go to your doctor regularly for a check-up.
Tell any other doctors, dentists, and pharmacists who are treating you that you are taking this medicine.
Things you must not do
Give this medicine to anyone else, even if their symptoms seem similar to yours.
Take your medicine to treat any other condition unless your doctor tells you to.
Stop taking your medicine, or change the dosage, without first 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.
Possible side effects
Tell your doctor as soon as possible if you do not feel well while you are taking prazosin or if you have any questions or
Do not be alarmed by the following list of side effects. You may not experience any of them. All medicines can have side
effects. Sometimes they are serious, but most of the time they are not.
If you are 65 years or older, you should be especially careful while taking prazosin. Report any side effects promptly to
Tell your doctor if you notice any of the following:
nausea, vomiting , feeling sick
constipation or diarrhoea
weakness, lack of energy
pain or fever
hair loss or thinning
poor bladder control
ringing in the ears (tinnitus)
problems getting to sleep
Tell your doctor immediately if you notice any of the following:
These may be serious side effects and you may need medical attention:
dizziness, spinning sensation or light-headedness when standing up
fast or pounding heart beat
skin problems such as rash, itching or hives
blurred vision or painful or red eyes
painful, continual erection
tingling or numbness in the hands or feet
swelling of the hands, feet or ankles
feelings of nervousness or depression
If you experience any of the following, stop taking your medicine and contact your doctor immediately or go to the Accident
and Emergency department at your nearest hospital.
These are very serious side effects and you may need urgent medical attention or hospitalisation
sharp pain in the stomach or back
fast or slow heart beat
fainting or passing out
hallucinations (seeing, hearing or feeling things that aren't there)
Other side effects not listed above may occur in some patients.
If you think you are having an allergic reaction to prazosin, do not take any more of this medicine and tell your doctor immediately
or go to the Accident and Emergency department at your nearest hospital.
Symptoms of an allergic reaction may include some or all of the following:
cough, shortness of breath, wheezing or difficulty breathing
swelling of the face, lips, tongue, throat or other parts of the body
rash, itching or hives on the skin
hay fever-like symptoms.
Storage and disposal
Keep your medicine in its original packaging until it is time to take it.
If you take your medicine out of its original packaging it 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
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 tells you to stop taking this medicine or it has passed its expiry date, your pharmacist can dispose of the
remaining medicine safely.
What Chemmart 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 tablet, 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
Chemmart Prazosin 1 mg tablets:
AUST R 73856
Chemmart Prazosin 2 mg tablets:
AUST R 73860
Chemmart Prazosin 5 mg tablets:
AUST R 73864
Apotex Pty Ltd
16 Giffnock Avenue
Macquarie Park, NSW 2113
This leaflet was prepared in December 2015