Clonidine is a type of medicine called a vasodilator.
Clonidine has many uses. It's mainly used to:
- prevent migraine or other similar types of headache
- treat hot flushes or sweats that may happen during the menopause
It's also sometimes used to treat high blood pressure (hypertension).
It helps to relax and widen blood vessels in the heart so blood can pass through them more easily.
Clonidine is only available on prescription.
It comes as tablets or as a liquid that you swallow. It's also available as an injection, but this is only given in hospital for emergency treatment of high blood pressure.
Who can take clonidine
Most adults aged 18 years old and over can take clonidine.
It's sometimes prescribed for children if a specialist recommends it.
Who may not be able to take clonidine
Clonidine is not suitable for some people.
To make sure clonidine is safe for you, or your child, tell your doctor if you:
- have ever had an allergic reaction to clonidine, any of its ingredients or any other medicine
- are pregnant, trying to get pregnant or breastfeeding
- have any heart or kidney problems
- have blood circulation problems in your hands, feet or lower legs, including Raynaud's or peripheral arterial disease (PAD) (also known as peripheral vascular disease)
- have ever had problems with blood circulation to the brain (cerebrovascular disease) such as stroke, transient ischaemic attacks (TIA) or brain aneurysm
- have ever had clinical depression
- have constipation
- have polyneuropathy, a type of peripheral neuropathy that affects several nerves in your body with symptoms such as tingling, unusual feeling, numbness, pins and needles or sharp pains in the hands, feet, arms or legs
- wear contact lenses – you may get dry eyes while taking clonidine, which may be a problem if you wear contact lenses
Dosage and strengths
Clonidine tablets come in 2 strengths: 100 micrograms or 25 micrograms. The liquid contains 50 micrograms in 5ml.
Dose for adults
Your dose of clonidine depends on what you're taking it for.
For preventing migraines or similar types of headaches, or for treating menopausal hot flushes or sweats, the usual dose for adults is 50 micrograms to 75 micrograms twice a day.
For high blood pressure, the usual starting dose for adults is 50 micrograms to 100 micrograms 3 times a day.
Your doctor will tell you how much to take and how often to take it.
Dose for children
The dose for children depends on why they’re taking it, how old they are and how much they weigh. A specialist will advise you on the correct dose.
Changes to your dose
If you're taking clonidine to prevent migraines or for menopausal hot flushes, your dose will usually stay the same as long as it seems to be working well and you are not having too many side effects.
If you're taking clonidine for high blood pressure, your doctor will gradually increase your dose until your blood pressure is under control. The maximum recommended dose is 1.2mg in total per day.
Over time your dose may need to go up or down according to your blood pressure readings.
How to take it
Try to spread the doses out as evenly as possible and take clonidine at the same times each day.
If you take it once a day, you can take it in the morning or the evening. But because clonidine can make you feel sleepy, you may prefer to take it around bedtime.
If you take it twice a day, take the first dose in the morning and the second dose in the evening. It's best to leave about 10 to 12 hours between doses.
If you take it 3 times a day, take the first dose in the morning, the second dose early afternoon and the third dose at bedtime. It's best to leave about 6 to 8 hours between doses.
Swallow the tablets whole with a drink of water. You can take clonidine with or without food.
The 100 microgram tablets can be cut in half if you need a 50 microgram dose but you do not have any 25 microgram tablets. Talk to your pharmacist about how to do this. It's best to use a special tablet-cutting device, available to buy in pharmacies.
Liquid clonidine should come with a plastic syringe or spoon to help you measure out the right dose. If you do not have a syringe or spoon, ask your pharmacist for one. Do not use a kitchen teaspoon as it will not measure the right amount.
How long to take it for
How long you'll take clonidine for depends on why you're taking it. For most conditions you'll need to keep taking clonidine for as long as it's working for you and you still need it. Some people take it for many months and even for years.
Do not stop taking clonidine suddenly as this can cause dangerously high blood pressure and withdrawal side effects.
If you take clonidine for high blood pressure, you'll probably need to take it for the rest of your life to protect against the risks of high blood pressure, such as heart attacks and strokes.
Keep taking it regularly, even if you feel well.
If you forget to take it
If you or your child forgets a dose of clonidine, take it as soon as you remember, unless it's nearly time for your next dose. In this case, skip the missed dose and take your next dose at the usual time.
Never take 2 doses at the same time. Never have an extra dose to make up for a forgotten one.
If you forget doses often, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicines.
If you take too much
Taking too much clonidine can cause:
- low blood pressure – this might make you faint feel dizzy
- a slow heart rate
- breathing difficulties
- being sick
- small pupils in your eyes
- dry mouth
- you or your child has taken more than your prescribed dose of clonidine
Go to 111.nhs.uk or call 111 . Call 111 if you're asking about a child under the age of 5 years.
If you need to go to A&E, do not drive yourself. Get someone else to drive you or call for an ambulance.
Take the clonidine packet, or the leaflet inside it, plus any remaining medicine with you.
Whatever you're taking clonidine for, stopping it suddenly can cause a dangerous increase in your blood pressure. It can also cause withdrawal side effects such as restlessness, heart palpitations, agitation, nervousness, tremor or shaking hands, headaches or feeling sick (nausea).
Do not stop taking clonidine without talking to a doctor. If you need to stop taking it, you'll need to reduce your dose gradually. Your doctor can advise you how to do this safely.
Common side effects
These common side effects of clonidine happen in more than 1 in 100 people. These side effects do not usually last long and there are things you can do to help cope with them:
Speak to a pharmacist or doctor if the advice on how to cope does not help and a side effect is still bothering you or does not go away.
Serious side effects
Serious side effects of clonidine are uncommon and happen in less than 1 in 100 people.
Call a doctor or contact 111 now if you get:
- heart problems such as an irregular heartbeat or heart palpitations, or an unusually slow heartbeat (bradycardia)
- feelings of confusion, problems understanding what is happening around you, or hallucinations (seeing or hearing things that are not real)
- stomach pain, vomiting and constipation symptoms all together – these can be symptoms of a rare condition called pseudo-obstruction of the large bowel
Go to 111.nhs.uk or call 111.
Serious allergic reaction
In rare cases, clonidine may cause a serious allergic reaction (anaphylaxis).
These are not all the side effects of clonidine. For a full list see the leaflet inside your medicine packet.
Clonidine and pregnancy
Clonidine is not recommended during pregnancy as little information is available on whether it's safe for the baby. Speak to your doctor, who will be able to suggest an alternative to clonidine to use during pregnancy.
If you're trying to get pregnant talk to your doctor about the benefits and possible harms of taking clonidine.
If you think you may be pregnant, or are already pregnant, get advice from your doctor as soon as possible. This is particularly important if you're taking clonidine to control blood pressure, since stopping it may cause your blood pressure to rise.
Clonidine and breastfeeding
It might be OK to take clonidine while breastfeeding but talk to your doctor or pharmacist first. It's best not to take clonidine if your baby was born prematurely, but your doctor will help you decide.
There is not much information about taking clonidine while breastfeeding, but information shows that small amounts of clonidine pass into breast milk. This is unlikely to cause side effects in your baby, but we do not know yet for certain.
Your doctor might recommend a different medicine for you to take while breastfeeding.
Clonidine might make you feel sleepy, so it's important not to share a bed with your baby while you're taking it.
If you take clonidine while breastfeeding, talk to your health visitor, midwife, pharmacist or doctor as soon as possible if you have any concerns, including if your baby:
- is not feeding as well as usual
- seems unusually sleepy
- seems much paler than usual
Clonidine and fertility
There's no evidence that clonidine affects fertility in either men or women.
Cautions with other medicines
There are some medicines that may increase the risk of side effects with clonidine or affect how well it works.
Tell your doctor or pharmacist if you're taking:
- other vasodilator medicines such as diazoxide or sodium nitroprusside
- medicines used to treat high blood pressure or heart problems, including diclofenac, digoxin, beta blockers such as propranolol, atenolol, bisoprolol or carvedilol, or calcium channel blockers such as diltiazem or verapamil – taking clonidine with these can sometimes lower your blood pressure or slow your heartbeat (pulse) too much
- medicines for an enlarged prostate
- medicines that make you pee more (diuretics)
- medicines for mental health problems, including antidepressants or antipsychotics
- medicines for Parkinson’s disease such as levodopa
- muscle relaxants such as baclofen or tizanidine
- medicines that make you sleepy such as anti-anxiety medicines or sleeping tablets
- non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen, naproxen, diclofenac, celecoxib or etoricoxib
- methylphenidate, for attention deficit hyperactivity disorder (ADHD)
Mixing clonidine with herbal remedies and supplements
There's not enough information to say that complementary medicines and herbal remedies are safe to take with clonidine. They're not tested in the same way as pharmacy and prescription medicines. They're generally not tested for the effect they have on other medicines.
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