Skip the main content if you do not want to read it as the next section.
The medicines most commonly used to treat high blood pressure are ACE inhibitors, angiotensin receptor blockers, calcium channel blockers, and thiazide diuretics. However, some people may not be able to take some of these medicines, or their blood pressures are not lowered enough by just using these medicines. If this is true for you, you may be asked to try a non-standard medicine.
These medicines are not commonly used, but they can be very effective for some people.
Alpha-blockers
Alpha-blockers block the action of the hormone adrenaline on your blood vessels. Adrenaline makes the muscles in the artery walls contract, which narrows the arteries and makes it more difficult for blood to flow through them. This raises your blood pressure, but alpha blockers stop adrenaline from having this effect.
Who should take alpha-blockers?
Alpha-blockers may be given to people who have not been able to control their blood pressure enough with other medicines. They may also be given to people with particularly high blood pressure, or who have a condition called phaeochromocytoma (where a benign growth on the adrenal gland causes too much adrenaline to be released into the blood).
Who should not take them?
Alpha-blocker medicines may make the muscles of the bladder more relaxed. Because of this they are normally not given to women because they may cause stress incontinence or loss of bladder control.
What are the most common side-effects?
If you are taking alpha-blockers, your body may not react so quickly to the effects of sitting up or standing up. Normally your arteries would tighten to help counter the effects of gravity, but if they react more slowly, then you may have a sudden drop in your blood pressure which can make you feel faint or dizzy. This is called postural hypotension.
Other common side-effects include tiredness, headaches and swelling of the ankles.
If you develop side-effects from your medicines, your doctor may be able to help by lowering your dose, or by changing your medicine. Do not stop taking any medicine without first speaking to your doctor.
Types of alpha-blocker
Most medicines have two names – the generic name (which is the name of the medicine itself) and the brand name (which is the name the medicine is sold under). This means different companies may make and sell the same medicine, but they may sell it with different brand names. The table below lists some alpha-blocker medicines currently used in the UK:
| Generic name | Brand names |
| Doxazosin | Cardura, Cardura XL, Doxadura, Doxazosin |
| Indoramin | Baratol |
| Prazosin | Hypovase |
| Terazosin | Hytrin |
Centrally acting drugs
Centrally acting drugs work directly on cells in the part of the brain that controls blood pressure. They work on these cells to cause the body to release hormones that make the heart beat less strongly and make the smaller blood vessels stay open. This action gives your blood more space in which to flow, and reduces the force with which it is pushed around. This lowers your blood pressure.
Who should take centrally acting drugs?
Centrally acting drugs may be given to people who have not been able to control their blood pressure enough with other medicines.
A particular type of centrally acting drug called methyldopa is sometimes used to treat high blood pressure in pregnant women. It is know to be safe to use during pregnancy because it does not have harmful effects on the developing baby. Once the baby is born, if the mother still has high blood pressure she will probably change to one of the main classes of blood pressure medicine.
What are the most common side-effects?
A common side-effect of these medicines is that you may feel tired and lacking in energy. You may also experience a dry mouth or fluid retention.
These medicines can also have some severe side-effects. In some people, they can cause depression, and men may experience erectile dysfunction. Methyldopa may also cause drug reactions, including liver problems.
Because they can have severe side-effects, centrally acting drugs are rarely used to treat high blood pressure, except in pregnancy. If you develop side-effects from your medicines, your doctor may be able to help by lowering your dose, or by changing your medicine. Do not stop taking any medicine without first speaking to your doctor.
Types of centrally acting drugs
Most medicines have two names – the generic name (which is the name of the medicine itself) and the brand name (which is the name the medicine is sold under). This means different companies may make and sell the same medicine, but they may sell it with different brand names. The table below lists some centrally acting drugs currently used in the UK:
| Generic name | Brand names |
| Clonidine | Catapres, Dixarit |
| Methyldopa | Aldomet, Methyldopa |
| Moxonidine | Moxonidine, Physiotens |
Direct-acting vasodilators
Direct-acting vasodilators work directly on the muscles in the walls of the small blood vessels, causing them to open up more. This gives the blood more space to flow through, which lowers your blood pressure.
Who should take direct-acting vasodilators?
Direct-acting vasodilators may be given to people who have not been able to control their blood pressure enough with other medicines.
A particular type of direct-acting vasodilator called hydralazine is sometimes given to people who have heart failure and who cannot take an ACE inhibitor or angiotensin receptor blocker.
What are the most common side-effects?
The main side-effects of these medicines come from the fact that they open up the smaller blood vessels. In particular they can cause headaches, flushing and heart palpitations.
These medicines cause an increase in heart rate and a greater fluid retention. Because of this, people taking a direct-acting vasodilator will normally be given a beta-blocker to help control their heart rate and a diuretic to increase their output of water (as urine).
A particular type of direct-acting vasodilator called minoxidil can cause unwanted hair growth.
If you develop side-effects from your medicines, your doctor may be able to help by lowering your dose, or by changing your medicine. Do not stop taking any medicine without first speaking to your doctor.
Types of direct-acting vasodilator
Most medicines have two names – the generic name (which is the name of the medicine itself) and the brand name (which is the name the medicine is sold under). This means different companies may make and sell the same medicine, but they may sell it with different brand names. The table below lists some direct-acting vasodilator medicines currently used in the UK:
| Generic name | Brand names |
| Hydralazine | Apresoline, Hydralazine |
| Minoxidil | Loniten |
Email
