Topamax is a billion dollar blockbuster drug used to help prevent migraine and epilepsy. It’s one of the most commonly prescribed migraine preventative drugs in the USA. So what is Topamax (also known by its generic name topiramate)?

It’s an antiepileptic medicine also known as an anticonvulsant. Anticonvulsants are a class of drugs which were originally designed to prevent seizures in those with epilepsy.

Topamax is the brand name developed by a division of Johnson & Johnson which held a patent to their formulation when approved in 1996. Once the patent expired a cheaper generic option became available in the form of topiramate. At the time of its approval in 2009, there were over 17 different generic manufacturers. [i]

Brand names for topiramate

Topamax, Topamax Sprinkle, Qudexy XR, Topiragen, Trokendi XR

Qudexy XR and Trokendi XR are both relatively new extended release formulations of topiramate.

It is available in the following formats:

  • Tablets: 25 to 200 mg
  • Sprinkle capsules: 15 and 25 mg
  • Capsule (Extended Release): 25 to 200 mg

Do I need a prescription for Topamax (topiramate)?


How does it work?

The short answer is “we’re not sure actually”.

Topiramate was originally developed for epilepsy. [ii] Those with epilepsy started noticing an improvement in their migraine condition in several case studies and from there a trial was conducted to test migraine patients specifically. It was not designed with migraine in mind but it is arguably an effective treatment for the prevention of migraine.

Epilepsy and migraine share a number of biological and clinical features in common. [ii] Perhaps not surprising to find that anticonvulsant medications may have a therapeutic benefit for both indications.

Scientific studies suggest topiramate reduces brain hyperexcitability, which is thought to provoke migraine attacks in those susceptible.

The ways in which a drug works is often referred to in clinical papers as its mechanism of action. Topiramate’s mechanism of action may involve[iii]:

  1. Blocking voltage-dependent sodium channels
  2. Augmenting the activity of the neurotransmitter gamma-aminobutyrate
  3. Antagonizing the AMPA/kainite subtype of the glutamate receptor
  4. Inhibiting the carbonic anhydrase enzyme

What does all that mean in English?

It essentially describes how Topamax blocks certain neurotransmitters or pathways in the brain as well as changing or altering how they behave.

How effective is Topamax (topiramate)?

The short answer – it’s considered to be an effective option for migraine prevention.

Both US and European authorities have given Topamax or topiramate what they term ‘Grade A’. Grade A is the highest rating a treatment can receive. The grade is a reflection of the quality of research evidence and the efficacy of its results according to the clinical evidence.

When several clinical research studies are collectively reviewed to analyze and evaluate research it is called a systematic review. Often meta-analysis is used to summarise the results of these studies.

Fortunately this work has been conducted on topiramate for the prevention of migraine attacks in adults. A nonprofit called The Cochrane Collaboration reviewed 17 studies and found that patients did reduce their frequency of migraine headaches per month versus placebo. They also found that patients were around twice as likely to reduce the number of attacks by 50% or more with topiramate than with placebo.[iv]

The scientific conclusion for this systematic review was that topiramate at a 100mg/day dosage can be effective and reasonably well-tolerated in adult patients.

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Side Effects

The same review from Cochrane acknowledged that whilst there were good results with topiramate, the occurrence of side effects were common but generally mild.[iv]

Topiramate can cause birth defects and is not suitable for certain people. View the following section on ‘Safety Profile’ for more details.

What side effects are considered common? Anything above a 10% incidence rate is considered to be ‘very common’ whilst anything with a 1%-10% incidence rate is considered ‘common’.[v] See below table for side effects or adverse effects.

Notice how the side effects are more likely to increase as the dose increases from 50 mg to 100 mg. Highlighted numbers are side effects which are considered to be ‘very common’.


Table reference: Topamax (topiramate) side effects [iii]

Some symptoms you might not recognize are defined below:

  • Hypoesthesia – reduced sense of touch or numbness
  • Dyspepsia – pain or uncomfortable sensation in the gut including reflux
  • Gastroenteritis – commonly termed ‘gastro’. An infection upsets the stomach
  • Psychomotor slowing- slowing of thought and physical activity such as movement and/or speech

Please note this is not a full list of potential side effects. There may be other serious side effects that you may be vulnerable to which is why you should speak to your doctor if considering whether topiramate may be appropriate.

Personal experience: As someone who used Topamax for several years I noticed several symptoms myself when taking a dose anywhere between 25 mg to 100 mg per day.

The first was the tingling sensation. This happened almost immediately after my first dose which I wasn’t prepared for. After speaking with my doctor and confirming everything was ok, I continued with the treatment and within the first week those symptoms had faded entirely.

The second common symptom was the sluggishness I felt in the morning. It was more difficult to get out of bed in the morning. I still felt tired, like my sleep wasn’t nearly as restful.

I would not call myself a morning person generally, but this side effect encouraged anyone around me to tip-toe until at least a half hour after I’d woken up.

The final two noticeable side effects I experienced was moodiness and cognition impairment including difficulty with memory.

‘Dopamax’ is a nickname coined by some which describes how you might feel on Topamax (or topiramate). You can see above the prevalence of this side effect. For those who experience it, it can become more obvious over time. I had been on Topamax for years… but towards the end I experienced around a 30% reduction in cognition. This was a noticeable impact on the speed, sharpness and clarity of thought I would have without Topamax.

Most noticeably I’d have difficulty remembering the names of certain things and to some degree, my memory of recent events was affected.

The most bothersome side effect were the mood changes. I became more easily agitated and grumpy. I had a temper on Topamax which I didn’t have otherwise.

As my condition improved due to Topamax and other preventative strategies I gradually weaned off Topamax. The side effects also faded.

Fortunately I did not have any serious side effects which would stop me using Topamax long term (several years).  Some of these are listed in the next section below. None of which are not common enough to be mentioned in the above table.

If serious side effects are common the drug is not likely to be approved by regulatory authorities like the FDA.


Topiramate when prescribed by a doctor who takes into account your full medical history, current medications and health profile are considered a safe and approved treatment by the FDA and other regulatory medical bodies around the world.

However there are important warnings and precautions that come along with this treatment.

For example, never stop suddenly taking the medication. This is a medication that requires a gradual withdrawal with staged reductions in dose. If the medication is suddenly halted then seizures may occur in those who do not normally experience them.

Topiramate also has several more uncommon but serious side effects:

  • Eye problems, including acute Myopia, which may involve difficulty seeing clearly as well as a build-up of fluid in the eye (which can lead to blindness if not treated).
  • Hyperammonemia which refers to high levels of ammonia in the blood.
  • Metabolic acidosis which is an elevated level of acid in the blood.
  • Encephalopathy which refers to brain disease, damage or other issues
  • Suicidal behavior or ideation can be increased in patients taking Topamax.
  • Fetal toxicity. Topamax can harm or cause birth defects in the unborn baby in a pregnant woman. It is also not appropriate for a nursing mother or mother who plans to become pregnant whilst using Topamax.
  • Kidney stones can be caused by Topamax. Doctors often advise patients to drink plenty of water throughout the day to help prevent kidney complications.

Major Drug Interactions

Topiramate like many other medications interacts with other medicines and can have dangerous consequences. It is important to ensure your doctor has a full list of everything you are currently taking.

Interactions of Topamax (topiramate) include:

  • Other antiepileptic drugs
  • Central Nervous System Depressants
  • Oral contraceptives
  • Lithium
  • Carbonic Anhydrase Inhibitors (eg. zonisamide or acetazolamide)
  • Hydrochlorothiazide (HCTZ)
  • Pioglitazone
  • Amitriptyline

People who should not use Topamax or topiramate:

  • Women who are pregnant, planning to get pregnant or nursing mothers.
  • Children under the age of 12 have not been evaluated in the efficacy or effectiveness of Topamax for migraine prevention. On a subjective note: I’d be asking the doctor what impact Topamax or topiramate could have on a developing brain. Personally, it’s not something I’m comfortable considering as a first line option for a child with migraine.
  • Patients with renal impairment (renal failure) or undergoing hemodialysis which is a type of dialysis to remove waste products from the blood.


Ranges from 25 mg to 200 mg per day.

Topiramate is one of those treatments where it is very appropriate to ‘Go Slow, Start Low’. It is often initiated at a dose of 25 mg per day with a gradual increase to your maximum tolerated dose.

Your maximum tolerated dose is basically how much you can take without the side effects or adverse events becoming worse than any benefit derived from the treatment.

In clinical trials a maximum dose of 200mg has been researched frequently. Interestingly, in epilepsy, studies have researched dosages up to 400mg.


In the US generic topiramate is covered by most Medicare and insurance plans. A 60 tablet (a one month supply) of 50mg can be purchased for as low as $10-15 per pack.

In the UK, a 60 pack of 50mg topiramate retails at £31.69.

In Australia, Topamax is listed on the national PBS scheme and is available for $25.02 per pack of 60 tablets. For the generic version, topiramate, the same quantity can be bought for $14.99.

In Canada, the 120 pack of 50mg is available for $288 USD. The generic is still $114.90 USD.

Important to remember for all medications

Overdosing is when you take more than your prescribed dose. Never overdose. If you believe an overdose has occurred visit the emergency department of your hospital. Take the medication container and pack with you even if it’s empty. Better to be safe than sorry.

The medication prescribed to you is only for you. Never share it with others who you believe have a similar condition. Your specific treatment may cause serious issues with others who do not share the same health profile, history or who are using other medications.

If you are having an operation or dental treatment, tell the practitioner what treatments you are currently taking.

Out of date medications should be disposed and can have unintended consequences if taken.

If you have questions about your treatment ask your pharmacist or doctor.

Never change or stop your treatment or dosage without first consulting your doctor.

User reviews:

Most of what we’ve heard so far has been based on what is available in clinical trials or medical reviews. Seeing how patients themselves rate topiramate, especially when compared to everything else they’ve tried, can be very interesting.

Below are effectiveness results from 3 separate sources.


Survey 1 from Curetogether had a survey that numbered 718 participants (n = 718).  11% found a major improvement with topiramate. 27%[vi]


Interestingly, a survey with 375 participants (n = 375) from Patients Like Me found different results.

35% of patients had a major improvement, 30% a moderate improvement and 18% a slight improvement.  27% had either no improvement or couldn’t tell. Patients were not able to report whether they believe topiramate had worsened their condition or not. [vii]

The final source is where 293 participants (n = 293) evaluated their treatment. Topiramate scored an overall 6.2 out of a possible 10. The best review with enough samples was 8 out of 10.[viii]

User side effects:

From the user reviews, 48% of patients report (n = 1236) severe or moderate side effects with topiramate. The most common side effect being weight loss (n = 94) followed by brain fog (n = 66), memory problems (n = 56) hands tingling (n = 54) and word fishing (n= 52).


There is a general agreement amongst users that at least 30% experience a moderate improvement with a further 11% to 35% experiencing major improvement depending on the source.

This could be considered similar to the systematic review of clinical research where twice as many patients report a 50% headache frequency reduction versus placebo.

Side effects from topiramate are common. Some might consider weight loss a welcomed side effect. Other side effects like tingling or word fishing might not be considered severe but some people may not tolerate memory problems or brain fog. Everyone is unique in the side effects they experience. Some may not experience any, whilst others may find them intolerable.

If you can tolerate the side effects, then topiramate may be considered an effective and useful treatment for migraine.

What about you? Has your experience with Topamax (topiramate) been positive or negative overall?

Get a list of the top proven preventative migraine treatments according to guideline recommendations from the US and Europe.

Article References

[i] Gever, J. Generic Topiramate Wins FDA Approval. MEdPage Today. April, 2009. Accessed 29 June 2017

[ii] Rothrock, J. F. (2012), Topiramate for Migraine Prevention: An Update. Headache: The Journal of Head and Face Pain, 52: 859–860. doi:10.1111/j.1526-4610.2012.02161.x

ii Rothrock, J. F. (2012), Topiramate for Migraine Prevention: An Update. Headache: The Journal of Head and Face Pain, 52: 859–860. doi:10.1111/j.1526-4610.2012.02161.x

[iii] Topamax Prescribing Information USA

[iv] Linde M, Mulleners WM, Chronicle EP, McCrory DC. Topiramate for the prophylaxis of episodic migraine in adults. Cochrane Database of Systematic Reviews 2013, Issue 6. Art. No.: CD010610. DOI: 10.1002/14651858.CD010610

[v] Collins, S. How are the words ‘rare’ and ‘common’ defined for side effects? I-base, April 2009. Accessed 29 June 2017

[vi] CureTogether 2017, Accessed 30 June 2017 <>

[vii] PatientsLikeMe 2017, Accessed 30 June 2017 <>

[viii] n.d., Accessed 30 June 2017 <>