Low blood pressure

Blood pressure is a measure of how forcefully your heart is pumping blood around your body. This is important because your blood carries oxygen from your lungs to your other organs, including your brain.

Blood pressure goes up and down naturally during the day. It may go up if you are stressed or doing physical activity and goes down when you are resting.

The autonomic nervous system (part of the brain, nerves and spinal cord) controls your blood pressure. This process involves sensors in your neck, which send signals about your blood pressure to your brain. The brain monitors your blood pressure and tells your heart and blood vessels when to adjust it.

The autonomic nervous system also sends or diverts blood to the parts of the body that need it most. This helps to control the supply as there is only a certain amount.

This happens during certain activities. For example, during exercise your blood pressure increases so your muscles can get more oxygen. Or, if you have eaten recently, more blood goes to your stomach to allow it to digest food, reducing blood pressure elsewhere.

If you are concerned about your blood pressure, you can ask your GP, Parkinson’s nurse or specialist to check it. If your GP surgery has a practice nurse, they can also take your blood pressure for you. In some cases your pharmacist may be able to check your blood pressure, too

To measure your blood pressure your doctor will listen to your pulse in your arm and take two readings from each beat.

To do this they will use a blood pressure monitoring machine with a stethoscope. A cuff is wrapped around your arm and pressure is increased to 180mm Hg and then decreased.

The first reading is a measure of the highest pressure when your heart pumps blood around your body. This is called systolic pressure. The second reading is a measure of the lowest pressure when your heart is resting between beats. This is called diastolic pressure. These two readings will give you a maximum and minimum blood pressure.

The readings are given as two numbers with both measures of pressure called ‘mm Hg’. For example, if your systolic pressure is 120mm Hg and your diastolic pressure is 70mm Hg, your blood pressure is written as 120/70.

A normal blood pressure reading is one between 90/60 and 140/90. Any readings outside of this range are classed as low or high.

Don’t worry if your blood pressure is higher or lower than expected – a one-off reading may be nothing to worry about. But if you are concerned that your blood pressure might still be too high or low after a period of time, see your doctor or Parkinson’s nurse.                                       

What is high blood pressure?

High blood pressure is a reading of 140/90 or higher.

High blood pressure usually has no obvious symptoms and many people have it without even knowing.

High blood pressure can increase the risk of a heart attack and stroke. You are also more likely to have problems with high blood pressure if you drink too much alcohol, eat a poor diet or smoke. High blood pressure can sometimes run in families.

You may be more likely to experience high blood pressure if you have other medical conditions, including diabetes, kidney disease and hardening of the arteries (atherosclerosis). Some medications can also cause high blood pressure.

What is low blood pressure?

Low blood pressure is a reading of below 90/60.

What causes low blood pressure?

Sometimes Parkinson’s itself can cause low blood pressure. This is because Parkinson’s affects the ‘autonomic nervous system,’ which controls blood pressure. In other cases, low blood pressure in Parkinson’s is linked to medication (see our section below on postural hypotension and medication for more information).

What are the symptoms of low blood pressure?

Blood pressure which is naturally low doesn’t cause any symptoms. But, if it drops too low you may experience:

• feeling dizzy or light-headed (especially when you stand up after sitting or lying down)
• blurred vision
• feeling weak
• feeling muddled or confused

If you experience symptoms that you think are linked to low blood pressure, get your blood pressure measured while you are sitting or lying and then after you have stood up for a couple of minutes. This will provide a better picture of your blood pressure overall.   

Postural hypotension (also known as orthostatic hypotension) is a large drop in blood pressure when standing or changing position.

For example, usually your body senses when you stand up, increases your heart rate and squeezes your blood vessels to move blood around your body. This process stops gravity from pooling blood in your legs.

But with postural hypotension this doesn’t happen. Because of this, it means less blood returns to the heart and reaches the brain. This can cause dizziness or fainting.

Postural hypotension can be a particular problem for people with Parkinson’s so it’s important to speak to your GP, specialist or Parkinson’s nurse about how to manage it.

Postural hypotension and medication

People with Parkinson’s are mostly likely to experience postural hypotension because of medication, including:

• your Parkinson’s drugs, particularly levodopa and dopamine agonists 
• drugs which help reduce swelling in your feet and ankles, called diuretics
• antidepressants
• blood pressure lowering drugs (anti-hypertensives)

It is particularly important to take your medication as prescribed. Postural hypotension alone may not be a reason to change drugs. If you are worried about your symptoms, speak to your specialist or Parkinson’s nurse about changing your medication. But remember not to stop taking your medication suddenly, because this can be dangerous.

Postural hypotension doesn’t usually cause serious problems if your Parkinson’s medication is built up gradually and your blood pressure is closely monitored.

If postural hypotension causes you particular problems, your GP, specialist or Parkinson’s nurse may be able to prescribe specific medication to help you manage it.

The drugs that may be prescribed include ephedrine, midodrine and fludrocortisone. However, this medication can interact with some Parkinson’s drugs so your healthcare professional will be able to advise you on whether this is the right choice for you.

If you have been taking medication to lower your blood pressure, make sure your blood pressure is checked regularly. Medication to lower blood pressure, combined with the drugs used for Parkinson’s, may make your blood pressure too low.

There are lots of things you can do to manage blood pressure. Healthcare professionals have suggested the following tips.

Changing position

Take your time when changing position to avoid dizzy spells – for example when rising from a chair to standing position. Get up slowly, especially if you have been dozing. Once you are out of your chair, stand still for a while until you feel steady.

Try not to stand still for long periods, for example while doing the ironing. Do tasks such as getting dressed sitting down and in stages. If you are doing something that means you have to stand, then move about a little. For example, rocking on your toes and then heels or change tasks for a while will keep your blood moving and keep your blood pressure up.

If you are getting out of bed, allow your feet to dangle on the floor for a few minutes before standing slowly.

Doing activities

Bend or reach for things slowly and hold on to something if you need to. This will mean you don’t lose your balance and fall over.

Do not sit in the sun or a hot environment for too long. Try to avoid a lot of activity when it’s hot and make sure you drink plenty of liquids. If you feel too hot, use a fan or a cold flannel to cool yourself down.

Gentle exercise can help. Try leg exercises such as moving the ankle and foot up and down, squeezing the calf muscles, gentle marching movements or crossing and uncrossing your legs. You can do these sitting, standing or lying in bed. Talk to a physiotherapist for more information about exercises.

Support stockings often help as they encourage circulation. They are available as tights or men’s socks, either on prescription or over the counter. Your local pharmacist may stock them or be able to tell you where you can get them.

Food and drink

Having a drink of water before you get up can sometimes help.

If you tend to feel dizzy after a meal, try drinking two small glasses of water at the end of the meal.

Taking some medication on an empty stomach may make the problem worse, as the medication will be absorbed more quickly than usual. But speak to your specialist or Parkinson’s nurse before changing the times of your medication.

Eating large and heavy hot meals may add to the problem. When you eat, the blood will go to the stomach and intestines to aid digestion, taking blood from other parts of the body to help digest the food. If you feel faint after eating, it is a good idea to keep meals small and frequent.

Avoid caffeine at night. Drinking less alcohol may also help. Your GP or a dietitian may suggest adding more salt to your diet. Don’t add extra salt without speaking to your GP or a dietitian first.

Monitor your blood pressure

You may find it useful to keep a diary of what triggers your symptoms and what makes them better or worse. This will help manage the problem.

If you have low (or high) blood pressure, you may need to tell the relevant driving authority, depending on what you drive.

At the time of printing, the government website states that you need to tell the DVLA in England Scotland and Wales or the DVA in Northern Ireland, if treatment for blood pressure causes side effects that could affect your ability to drive.

Please check with your relevant authority if you have problems with your blood pressure, as the rules may have recently changed.

Remember that you must contact your relevant driving licensing agency when you are diagnosed with Parkinson’s.