Topamax (topiramate) is a medication that has been approved for use in Australia for the treatment of epilepsy in adults and children. Topamax has also been approved for the treatment of migraine headaches in adults when alternative treatments (such as beta-blockers or pizotifen) have caused severe side effects, or are not appropriate due to possible side effects. Reports of common and potentially unpleasant side effects of Topamax have caused some concern amongst patients. However, these side effects tend to be temporary, controllable and/or avoidable if the dosage of Topamax is properly managed.
Several side effects have been reported following the use of Topamax as add-on therapy for epilepsy. In particular, more than 10% of adult patients administered Topamax reported paraesthesia (pins and needles, tingling), dizziness, fatigue, anorexia, weight decrease, speech problems, diarrhoea, cognitive difficulties (such as poor concentration and memory), and ataxia (problems with physical co-ordination).
Side effects experienced by 1-10% of patients included altered sense of taste, hypoaesthesia (loss of skin sensitivity to pain or touch), insomnia, nausea, renal calculi (kidney stones) and mood problems (including aggression, depression and psychosis).
Similar side effects have been reported following the use of Topamax to treat migraine. However the amount of Topamax required to reduce migraine occurrence is lower, therefore the occurrence of side effects also tends to be lower. Very common side effects (>10%) in children include personality disorder, anorexia, nervousness, somnolence (strong desire for sleep) and fatigue.
Side effects associated with the functioning of the central nervous system (CNS), including dizziness, slowed thinking, somnolence, ataxia, fatigue, confusion, and impaired concentration, tend to be temporary, but can be avoided. In general, CNS side effects can be avoided in adults by administering Topamax at a low starting dosage (approx. 25mg), and escalating the dose slowly, (approx. 25mg per week). Side effects are also experienced more often at higher target doses of Topamax. Therefore a target adult dose of 100mg for epilepsy monotherapy or for the treatment of migraine is recommended (recommended doses are higher for epilepsy add-on therapy). It should be emphasised that CNS side effects are likely to be temporary. Early research trials found that side effects such as fatigue and cognitive impairment resolved within 2 months in almost 90% of cases.
Paraesthesia is the most commonly reported side effect of Topamax. Approximately 35% to 50% of patients report temporary numbness and tingling around the mouth and in the limbs. Paraesthesia is usually mild and temporary and does not result in nerve damage. Current research is examining the possibility that treatment with potassium supplementation may reduce the severity of paresthesia.
Other side effects such as kidney stones, an altered sense of taste (taste perversion) and weight loss can also be managed. Renal calculi or kidney stones can be avoided by increasing fluid (preferably water) intake. Taste perversion is usually limited to carbonated (fizzy) drinks due to the chemical makeup of Topamax. Carbonated drinks (and potentially other drinks or foods) may taste odd or unpleasant. This side effect is completely harmless and could help wean the patient off unhealthy sugary drinks! Prior knowledge of this possible side effect can assist in reducing patient anxiety. Weight loss with Topamax is usually in the range of 2-4% of total body weight. Adults and children of normal or low body weight should be advised to eat higher calorie meals, avoid fasting and/or consider taking additional nutritional supplements.
Cognitive impairments associated with Topamax are usually dose related. Therefore lower doses will result in fewer problems with memory, language and concentration. Simple strategies can be adopted to help tolerate these problems if they occur, for example writing things down, and keeping lists. An inability or delay in ‘finding the right word’ is often reported. If cognitive impairments do occur, it is worth considering whether these side effects are tolerable in light of improvements in epileptic or migraine symptoms.
Further research has suggested that mood disturbances such as aggression, psychosis, anxiety and depression are related to higher starting doses, rapid increases in dose, a previous history of psychiatric illness or a family history of psychiatric illness. To avoid psychiatric problems caused by rapid dose increases, increases of around 25 mg per week are recommended (your doctor may adjust amount according to recommended guidelines and the severity of your condition). Patients with a personal or family history of psychiatric illness should be carefully assessed for their suitability for Topamax therapy, and then carefully monitored during therapy.
In general, side effects can be avoided by starting Topamax at a low dose and increasing it slowly to the lowest possible target dosage. Alternative or additional strategies can be adopted to alleviate side effects if they occur. If you are concerned about managing side effects of Topamax, or if you are experiencing severe side effects please consult your doctor for help and advice.
Top tips for managing side effects
- Discuss possible side effects with your doctor to reduce anxiety if they occur
- Drink lots of water
- Avoid fizzy drinks
- Eat regular meals and avoid fasting
- Eat higher calorie meals or take supplements if unwanted weight loss occurs
- Compensate for cognitive side effects by writing things down and keeping lists
- Evaluate whether side effects are tolerable in light of improvements in epilepsy or migraine symptoms
- Remember that most side effects are harmless and temporary. However, check with your doctor if side effects are uncomfortable or intolerable.
- Department of Health and Ageing. Topiramate in the current Pharmaceutical Benefits Schedule [document on the Internet]. Australia: Commonwealth Government of Australia [updated 2008 June 25; cited 2008 July 30]. Available from: http://www.pbs.gov.au/html/healthpro/search/results?term=topamax&scope=PBS+STATIC&form-type=simple
- National Prescribing Service RADAR (Rational Assessment of Drugs and Research). Topiramate (Topamax) for migraine prevention [document on the internet]. Surry Hills: National Prescribing Service Limited; c2005 [Updated November 2007; Accessed July 30 2008]. Available from: http://www.npsradar.org.au/site.php?page=1&content=/npsradar/content/topiramate.html
- Topamax Tablets and Sprinkle Capsules Product Information. North Ryde Australia: JANSSEN-CILAG Pty Ltd. 2008 May 5
- Silberstein SD. Topiramate in Migraine Prevention. Headache 2005; 45[Suppl 1]: S57-S65.
- Brandes JL. Practical Use of Topiramate for Migraine Prevention. Headache 2005; 45[Suppl 1]: S66-S73.
- Mula M, Trimble M R, Lhatoo SD, Sander JWAS. Topiramate and Psychiatric Adverse Events in Patients with Epilepsy. Epilepsia, 2003; 44(5): 659-663.