Medicines & Supplements A to Z > Topiramate


Last updated on 08/07/2021.

Overview   |   Dosage   |    Side Effects   |   Precautions  |   Tips  |   Where To Buy  

GENERIC NAME: Topiramate


BRAND NAME(S) IN HONG KONG: Topamax, Topamax Sprinkle

DRUG CLASS: Anticonvulsants, Central nervous system agents

SUB CLASS: Miscellaneous anticonvulsants, Carbonic anhydrase inhibitors

USED FOR: Treatment and prevention of seizures and epilepsy, Migraine prevention

– 25mg, 50mg, 100mg, 200mg (tablets)
– 15mg, 25mg (Topamax Sprinkle®) (capsules)

What is Topiramate for?

Topiramate is a miscellaneous anticonvulsant and a carbonic anhydrase inhibitor. It can decrease and prevent the spread of abnormal electrical signals in the brain to prevent migraine and treat various types of seizures, including primary generalized tonic-clonic seizures, partial seizures and seizures associated with Lennox-Gastaut.

How to use it?

Topiramate can be taken orally as tablets or sprinkle capsules. The tablets should not be crushed or chewed, where the sprinkle capsules can be opened and sprinkled the entire contents on a small amount (teaspoon) of soft food. This drug-food mixture should be swallowed immediately and not chewed.

Listed below are the indication and the dosages, which patients with poor renal function may need a lower dose. 

Monotherapy for partial seizures and primary generalized tonic-clonic seizures:
Patients 10 years of age and older:
Initial: 25 mg twice daily, and increased by 25 mg/dose every week up to 100 mg twice daily. Then, it may further be increased by 100 mg/dose every week.
Maintenance: 200 mg twice daily.

Pediatrics patients 2 – 9 years:
Initial: 25 mg once daily in the evening for the 1st week, and increased to 25 mg twice daily in the 2nd week. Then, it may further by 25-50 mg/day at weekly intervals over 5-7 weeks
11 kg: 150 – 250 mg/day in two divided doses.
12 – 22 kg: 200 – 300 mg/day in two divided doses.
23 – 31 kg: 200 – 350 mg/day in two divided doses.
32 – 38 kg: 250 – 350 mg/day in two divided doses.
> 38 kg: 250 – 400 mg/day in two divided doses.

Adjunctive therapy for partial seizures, primary generalized tonic-clonic seizures, and Lennox-Gastaut syndrome:
Patients 17 years of age and older:
Initial: 25-50 mg/day, and increased by 25-50 mg/day every week.
Maintenance: 200 mg twice daily.

Pediatrics patients 2 – 16 years:
Initial: 1-3 mg/kg/day once daily in the evening for the 1st week, and increased in 1-3 mg/kg/day increments every 1-2 week in two divided doses.
Maintenance: 5-9 mg/kg/day in two divided doses, without exceeding the maximum
Maximum: 400 mg/day

Prevention of Migraine:
Patients 12 years of age and older
Initial: 25 mg once daily in the evening, and increased by 25 mg/dose every week.
Maintenance: 50 mg twice daily.

What are the side effects of Topiramate?

Common side effects of Topiramate include paresthesia, anorexia, weight loss, fatigue, dizziness, somnolence, fever, upper respiratory tract infection.

Who should not take Topiramate?

The following patients should use Topiramate in caution:
– Patients with metabolic acidosis who are taking concomitant metformin
– Pregnancy and women in childbearing years not using effective contraception
– People who are allergic to Topiramate or any component of the formulation

Pharmacist Tips:

– Topamax Sprinkle® capsules may be swallowed whole or may be opened and sprinkled on a teaspoon of soft food. Drink fluids right after eating the food and medicine mixture to make sure it is all swallowed. Do not chew the food and medicine mixture, and do not store any medicine and food mixture for later use.
– Drink plenty of fluids during the day. This may help prevent kidney stones while taking Topiramate.
– Do not stop taking Topiramate suddenly as it can cause seizures.
– Do not drive or operate machinery until you know the effect of the medicine.

Common dosing schedule:
Topiramate can be taken with or without food. If it is once-daily dosing, it should be administered in the evening, while twice-daily dosing should be administered in the morning and evening. 

This schedule is for reference only, adjustments may be made according to individual needs.

Some common medications Topiramate may interact with:
– Contraceptives, e.g. Levonorgestrel
– Antidiabetics, e.g. Metformin, Pioglitazone
– Antiepileptics, e.g. Carbamazepine, Phenytoin, Valproic acid
– Carbonic anhydrase inhibitors, e.g. Acetazolamide

Please notify your doctor or pharmacist if you are taking the above medication, dosage adjustments might be needed.

Where to buy Topiramate in Hong Kong?

In Hong Kong, Topiramate is a prescription only medicine, and requires a prescription from a doctor to be purchased in a pharmacy. It can also be obtained from doctors. To find a pharmacy near you, refer to the list of pharmacies (“Authorized Sellers of Poisons”) from the Hong Kong Department of Health.

For more information about drug names and ingredients, you can visit Hong Kong’s Drug Office at

Need more information?

For detailed information about the use of Topiramate in children, pregnancy and breastfeeding, and for questions about drug interactions, please check with your pharmacist or doctor.

Disclaimer: our goal is to provide you with the most relevant drug information and common dosage for Hong Kong. This information does not constitute medical advice. For specific treatment recommendations and advice, always discuss with your doctor or pharmacist, and follow the instructions included with your specific medicine.