Like all medicines, doxazosin can cause side effects, but many people have no side effects, or only minor ones.
Side effects often improve as your body gets used to the medicine.
Common side effects
These common side effects of doxazosin happen in more than 1 in 100 people. They're usually mild and only last a short time. There are things you can do to help cope with them:
Feeling weak, sleepy or dizzy
If doxazosin makes you feel weak, sleepy, dizzy, or like everything around you is spinning (vertigo), stop what you're doing and sit or lie down until you feel better. Do not drive, cycle or use tools or machinery. It's best not to drink alcohol, as it will make you feel worse. If you feel sleepy, it may help to take your medicine at night time.
If you're still feeling dizzy after a week, or all of the time, speak to your doctor.
Headaches
Make sure you rest and drink plenty of fluids. Do not drink too much alcohol. Ask your pharmacist to recommend a painkiller.
Talk to your doctor if the headaches are severe or last longer than a few days.
Swollen feet, ankles or fingers
Raise your legs, or the swollen area, onto a chair or pillows when you can.
Urinary tract infection (UTI) or cystitis
Contact your doctor if you have symptoms of a UTI as you may need treatment. Symptoms can include needing to pee suddenly or more often than usual, pain or a burning sensation when peeing, and smelly or cloudy pee.
Rest and drink plenty of fluids. This helps your body to flush out bacteria.
Stomach pain or back pain
Try to rest and relax. It can help to eat and drink slowly, and have smaller and more frequent meals. Take a painkiller like paracetamol. Place a hot water bottle on your stomach or back, or between your thighs.
If you're in a lot of pain, speak to your pharmacist or doctor.
Feeling sick (nausea), indigestion or heartburn
Stick to simple meals and avoid rich or spicy food. It might help to take your doxazosin after you have eaten. Drink plenty of water or other fluids to avoid dehydration. If you're feeling sick, take small, frequent sips.
Talk to your doctor or pharmacist if this advice does not help or the side effects last more than a few days:
Serious side effects
Call your doctor or call 111 now if:
- the whites of your eyes turn yellow, or your skin turns yellow although this can be harder to see on brown and black skin – these can be signs of liver problems
- you get unexplained bruising or bleed easily – these can be signs of a blood problem
Immediate action required: Call 999 now if:
- you get chest pain, an irregular heartbeat or you can feel your heartbeat (palpitations) – these can be signs of heart problems
Immediate action required: Call 999 or go to A&E now if you get:
- weak arms or legs or problems speaking – these can be signs of a stroke
- a painful erection that lasts 2 or more hours
- shortness of breath or difficulty breathing – these can be signs of lung problems
Serious allergic reaction
In rare cases, doxazosin may cause a serious allergic reaction (anaphylaxis).
Immediate action required: Call 999 now if:
- your lips, mouth, throat or tongue suddenly become swollen
- you're breathing very fast or struggling to breathe (you may become very wheezy or feel like you're choking or gasping for air)
- your throat feels tight or you're struggling to swallow
- your skin, tongue or lips turn blue, grey or pale (if you have black or brown skin, this may be easier to see on the palms of your hands or soles of your feet)
- you suddenly become very confused, drowsy or dizzy
- someone faints and cannot be woken up
- a child is limp, floppy or not responding like they normally do (their head may fall to the side, backwards or forwards, or they may find it difficult to lift their head or focus on your face)
You or the person who's unwell may also have a rash that's swollen, raised, itchy, blistered or peeling.
These can be signs of a serious allergic reaction and may need immediate treatment in hospital.
Other side effects
These are not all the side effects of doxazosin. For a full list, see the leaflet inside your medicine packet.
You can report any suspected side effect using the Yellow Card safety scheme.