Topiramate

What is topiramate?

Topiramate is a prescription-only medicine used to treat epilepsy and to prevent migraines. It belongs to a group of medicines called antiepileptics or anticonvulsants – a common brand name for topiramate is Topamax[1]. 

What is topiramate used for?

Topiramate is prescribed for conditions including epilepsy, to help control seizures in adults and children. It is also used to help prevent migraine headaches in adults[1]. 

How does topiramate work?

Topiramate works by calming overactive nerve activity in the brain. Specifically, it affects several processes, including[1]: 

• Inhibiting glutamate activity, a neurotransmitter, which are chemical messengers in the brain that stimulate neuronal activity 

• Stimulating GABA-receptor activity which inhibit neuronal activityCombined, these actions block neuronal excitability and help reduce seizure activity and prevent migraines. 

Topiramate also blocks sodium channels further preventing seizure activity. 

Who can take topiramate?

Topiramate can usually safely be taken by adults and children aged two years and over for epilepsy. It may also be taken by most adults for migraine prevention. 

There are several important safety aspects with topiramate. You must not use topiramate if you are pregnant or are thinking of getting pregnant due to risk of harm to unborn child. If you are a female of childbearing potential, you must fulfil the conditions of the Pregnancy Prevention Programme.  It also may not be suitable for people who have a history of kidney problems especially kidney stones, eye problems especially glaucoma, acute porphyria, metabolic acidosis, liver problems, a growth problem or are on a high fat diet such as ketogenic[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 topiramate?

Most doses of topiramate are taken once or twice each day. You’ll usually be prescribed tablets to take with or without food by swallowing them whole. Drink plenty of water throughout the day to help reduce the risk of kidney stones. It’s important not to chew or crush the tablets as this can impair how well they work and leave a bitter taste in your mouth. 

If you’re using sprinkle capsules, these can be opened and sprinkled onto soft food, but should not be chewed. Always follow the instructions provided by your doctor or pharmacist for best results[1]. 

What is the typical dosage of topiramate?

Topiramate comes as tablets, capsules, and liquid. The typical dose of topiramate varies depending on your condition and how well you respond to treatment. In general, treatment starts with a low dose of 25mg to 50mg a day. This is then gradually increased up to strengths from 100mg to 400mg depending on your condition. Your doctor or pharmacist will determine the most appropriate dose for you, considering efficacy and safety[1]. 

Can you stop taking topiramate suddenly?

It’s important not to stop taking topiramate suddenly. Doing so can lead to serious side effects such as seizures or withdrawal symptoms. Instead, if you need to stop taking topiramate, your doctor or pharmacist will help you reduce the dose gradually and safely[1]. 

What should you do if you take too much topiramate?

Taking too much topiramate can cause serious symptoms, such as drowsiness, speech difficulties, blurred vision, convulsions, and even loss of consciousness. You should call 999 or go to A&E immediately if you or someone else has taken too much[1].  

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

You can take a missed dose as soon as you remember. But if your next dose is due soon, skip the missed one and continue with your usual schedule. Do not take a double dose if you missed one – this can bring dangerous side effects[1]. 

What medicines should you avoid while taking topiramate?

Topiramate can interact with other medicines. These include other epilepsy medicines such as phenytoin, carbamazepine and valproate (increasing their concentration and risk of toxicity), and oral contraceptives (may reduce their effectiveness). It can also interact to lithium, diuretics, St John’s wort, and vitamin C or calcium supplements[1].  

Topiramate may also interact with[1]: 

• Antipsychotic medicines like risperidone 

• Heart and blood pressure medicines like diltiazem, hydrochlorothiazide or propranolol 

• Depression and anxiety medication like venlafaxine or amitriptyline 

• Diabetes medication like metformin, glibenclamide or pioglitazone.  

Please note this is not a complete list, 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 topiramate?

Topiramate can bring several common, yet mild, side effects. These usually pass quickly. They may include one or several of feeling tiredness or drowsiness, or experiencing dizziness, loss of appetite, nausea, diarrhoea or constipation. You may also notice weight loss, tingling in the hands or feet, mood changes or depression, problems with concentration or memory, speech or language difficulties, or vision changes[1].  

There are also some potentially more serious side effects, including[1]: 

• Eye pain or sudden changes in vision, which may be signs of glaucoma 

• Severe mood changes or suicidal thoughts 

• Kidney stones, which may cause pain in the side or back 

• Lack of sweating in children in hot weather causing body temperatures to rise 

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 topiramate

How long does topiramate take to work? 

When you first start taking topiramate, it can take several weeks for it to become fully effective. Speak to your doctor or pharmacist if you are not noticing any benefits[1]. 

Can I drink alcohol while taking topiramate? 

It is best to avoid alcohol while taking topiramate, as it can increase side effects such as drowsiness and dizziness[1]. 

Will topiramate affect my weight? 

Topiramate may cause weight loss in some people – this is a fairly common side effect[1]. 

Can I take topiramate during pregnancy? 

Topiramate is not recommended during pregnancy and must not be used unless there is no suitable alternative treatment and under the advice and care of a specialist due to the risk of birth defects and harm to the unborn child. If you are female of childbearing potential, it is important you discuss the risks with your doctor and follow the conditions of the Pregnancy Prevention Programme[1]. 

Does topiramate affect contraception? 

Yes, topiramate can reduce the effectiveness of hormonal contraceptives. You may need to use additional methods of contraception while taking it or highly effective measures such as long-acting reversible contraceptive[1]. 

Can I drive while taking topiramate? 

It’s best to avoid driving or operating machinery if you feel drowsy or dizzy until you know how topiramate affects you. If you feel drowsy or dizzy, do not drive, this is both for your safety and that of those around you[1]. 

Are there long-term side effects of topiramate? 

Some people may experience long-term effects when taking topiramate, such as memory problems or mood changes. Your medical professional will monitor you regularly to help avoid or limit these[1]. 

What is the Pregnancy Prevention Programme? 

The Pregnancy Prevention Programme is a set of measures designed to minimise the risk of pregnancy in women who are taking certain medications known to cause birth defects. It is important you understand the risks when taking these medications and the need to use effective contraception. If you become pregnant or are planning on having a baby, it is important to speak to your doctor before making any changes to your medication[3].  

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