Clonidine

What is clonidine?

Clonidine is a prescription medicine classed as a vasodilator and an alpha-2 adrenergic agonist. It works by relaxing and widening blood vessels, which helps reduce blood pressure, and affecting nerve signals in the brain, giving it sedative and pain-relieving properties[1].

What is clonidine used for?

Clonidine is commonly used to treat conditions such as migraine and cluster headaches. It’s also prescribed to ease the symptoms of hot flushes and night sweats during menopause. It is sometimes used to treat high blood pressure too[1]. 

How does clonidine work?

Clonidine works by stimulating alpha-2 receptors in the brain. This action reduces the activity of the sympathetic nervous system – lowering both heart rate and blood pressure. Clonidine also affects pain pathways by reducing the release of certain pain-related chemicals such as glutamate and substance P[1].  

Who can take clonidine?

Most adults can safely take clonidine. It may sometimes be used with children under specialist care. However, it may not be suitable for people who[1]: 

• Have low blood pressure 

• Have heart rhythm problems 

• Have kidney problems 

• Have blood circulation problems in your hands, feet, or legs, including Raynaud’s and PAD 

• Have had problems with blood circulation to the brain, like a stroke, aneurysm or transient ischaemic attacks 

• Have ever had depression 

• Have constipation 

• Have polyneuropathy affecting your body’s nerves 

• Wear contact lenses 

• Are allergic to clonidine 

It’s also generally not prescribed for those who are pregnant, trying to get pregnant, or breastfeeding, unless advised by a doctor, or people taking medicines that interact with clonidine[1]. 

Please tell your doctor or pharmacist about any conditions you may have or medication you take before you start treatment, and always follow the instructions in the Patient Information Leaflet[2].  

How do you take clonidine?

Clonidine is usually taken two or three times a day, depending on your condition. You can take it with or without food, but try to take it at the same times each day, spread evenly. If you take it once daily, take it before bedtime as it can make you feel sleept. If you take it twice a day, take the first dose in the morning and the second in the evening, with a gap of 10 to 12 hours. If you take it three times a day, take the first dose in the morning, the second dose early afternoon, and the third dose at bedtime, with a gap of 6 to 8 hours between doses. You should swallow the tablets whole with water, and follow your doctor or pharmacist’s instructions carefully[1]. 

What is the typical dosage of clonidine?

Clonidine tablets come in two strengths: 25  micrograms or 100 micrograms. The liquid version contains 50mg in 5ml. The typical starting dose for adults is 50 micrograms, two to three times a day. Over time, this may be increased gradually to a maintenance dose of 75 to 150 micrograms two to three times a day. The maximum daily dose is generally no more than 450 micrograms. Injectable forms are only used in hospital[1]. 

Can you stop taking clonidine suddenly?

You should not stop taking clonidine suddenly. This could cause a dangerous rise in blood pressure and withdrawal symptoms such as anxiety, headaches or tremors. For this reason, it’s always best to follow your doctor or pharmacist’s advice on how to stop safely, which usually involves reducing the dose gradually over time[1]. 

What should you do if you take too much clonidine?

Taking too much clonidine can potentially cause several dangerous conditions. The most common signs of overdose may include severe drowsiness, a slow heart rate, low blood pressure, and shallow or slow breathing[1]. 

Call 999 or go to A&E immediately if you or someone else has taken too much clonidine. 

What should you do if you forget a dose of clonidine?

If you forget to take a dose, take it as soon as you remember. However, if it is nearly time for your next dose, skip the missed dose. Never take two doses at the same time to make up for a missed dose as this can cause unwanted symptoms[1]. 

What medicines should you avoid while taking clonidine?

Clonidine can interact with several medicines, including[1]: 

• Beta-blockers such as propranolol, atenolol, bisoprolol, or carvedilol 

• Heart or blood pressure medication like diclofenac or digoxin 

• Calcium channel blockers like diltiazem or verapamil 

• Medicines for an enlarged prostate 

• Diuretics 

• Tricyclic antidepressants or antipsychotics  

• Parkinson’s medication like levodopa 

• Muscle relaxants like baclofen or tizanidine 

• NSAIDs like ibuprofen, naproxen, and diclofenac 

• ADHD medication like methylphenidate 

• Sedatives and sleeping tablets 

• Other medicines used to lower blood pressure 

Always inform your doctor or pharmacist about all medications and supplements you take before you start a new medicine, and follow the instructions in the Patient Information Leaflet[2]. 

What are the side effects of clonidine?

The most commonly seen side effects when taking clonidine are feeling tired, having a dry mouth, constipation, dizziness, and a slow heart rate. Generally, these are mild and pass in time[1]. 

There are some more serious side effects that would need medical attention. These include fainting and irregular heartbeat – although these are rare[1].  

You should contact your GP if you experience any of these symptoms. In rare cases, the medicine may cause a serious allergic reaction (anaphylaxis). You should call 999 or visit A&E immediately if you believe this is happening[1]. 

Symptoms of anaphylaxis include[1]:  

• Difficulty breathing  

• Tightness in throat and chest  

• Swelling of the tongue or throat  

• Feeling faint or dizzy  

• Blue/grey skin or lips  

• Loss of consciousness 

If you experience any side effects, including those not listed, you are encouraged to report them via the Yellow Card Scheme or contact your doctor, pharmacist, or nurse. This information is intended as a summary for general awareness and does not replace professional medical advice. 

The information provided in the side effects section is not a comprehensive list of all possible side effects associated with this medication. For a complete list of side effects, please refer to the Patient Information Leaflet (PIL) provided with your medication or consult your healthcare professional[2]. 

Frequently asked questions about clonidine

How long does clonidine take to work? 

Clonidine usually takes between two and four weeks to have its full effect, however many people may see results sooner or later than that. Speak to your medical professional if you’re concerned about timescales[1]. 

Can I drink alcohol with clonidine? 

It is best to avoid alcohol when taking clonidine, as it can increase the risk of drowsiness and dizziness[1]. 

Is clonidine addictive? 

Clonidine is not considered an addictive substance. However, stopping it suddenly can cause withdrawal symptoms, so you should manage this with your doctor or pharmacist’s guidance[1]. 

Can I drive while taking clonidine? 

For the sake of your safety and people around you, you should avoid driving if clonidine makes you feel drowsy or dizzy[1]. Do not drive until you know how clonidine affects you. 

Can children take clonidine? 

In some cases, yes, children can take clonidine – it’s sometimes prescribed for children under specialist supervision[1]. 

Can I take clonidine long term? 

You can usually take clonidine long term if your doctor recommends it and you are regularly monitored[1]. 

What foods or drinks should I avoid while taking clonidine? 

There are no specific food restrictions when you take clonidine. It’s best to avoid alcohol while taking it as this can cause unpleasant side effects[1]. 

What should I do if I feel faint or dizzy while taking clonidine? 

If you start to feel faint after taking clonidine, sit or lie down right away. It will usually pass. If symptoms persist, tell your doctor or pharmacist who will advise you of the best way forward[1]. 

For the official NHS guide to clonidine, visit their website.