Topamax dosage, forms, and strengths

Topamax (topiramate) is an anticonvulsant approved by the Food and Drug Administration (FDA). In addition to treating and preventing seizures and seizure disorders like epilepsy, Topamax is also used to prevent migraine headaches. 

Topamax’s exact mechanism of action is unknown, but it’s thought to prevent seizures and migraines because it calms hyperactivity in the brain and nervous system. Doctors may prescribe Topamax off-label for medical conditions that it is not approved to treat, but has proven to be beneficial for. For example, Topamax is sometimes prescribed off-label to treat bipolar disorder, sleep-related eating disorder, nightmares associated with post-traumatic stress disorder (PTSD), and alcohol dependence.

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Topamax forms and strengths

Topamax can be taken by mouth in a variety of dosage forms. Topamax is available as regular-release sprinkle capsules or tablets. 

• Sprinkle capsules: 15 mg, 25 mg

• Tablets: 25 mg, 50 mg, 100 mg, 200 mg 

Topamax dosage for adults

Topamax is approved to treat and prevent seizures and to prevent migraines in adults. It can also be used for other health conditions like sleep-related eating disorders and nightmares associated with PTSD. Topamax dosing will depend on the type and severity of the condition being treated. The following table lists dosages for Topamax when used by itself (monotherapy). 

Topamax dosage for seizures 

Topamax works to treat and prevent seizures by calming hyperactivity in the brain and nervous system. Topamax can be taken alone or with other seizure medications (adjunctive therapy). 

Topamax is initially prescribed at a low dose, and then target doses are achieved by titration. Low starting doses are increased in 25 mg increments over six weeks:

• Standard adult dosage for seizures: 400 mg per day taken in two divided doses 

• Maximum adult dosage for seizures: 400 mg per day taken in two divided doses

More than 400 mg of Topamax per day has not been proven to be more effective and may increase the chance of side effects. 

Topamax for migraines

For migraine headaches, start Topamax at 25 mg taken in the evening for one week. It may be increased by up to 50mg of the daily dose per week. By week four, up to 100 mg of Topamax can be taken in the morning and evening. 

• Standard adult dosage for migraines: 100 mg per day taken in two divided doses 

• Maximum adult dosage for migraines: 100 mg per day taken in two divided doses

Topamax for sleep-related eating disorder

Sometimes, Topamax is used off-label to treat sleep-related eating disorders, characterized by a partial arousal from sleep followed by compulsive food consumption.

The starting daily dose of Topamax for this disorder is 25 mg, taken nightly for the first week. Over time the dose can be increased to up to 100 mg.

• Standard adult dosage for sleep-related eating disorder: 25-100 mg taken once per day 

• Maximum adult dosage for sleep-related eating disorder: 100 mg taken once per day 

Topamax for nightmares associated with PTSD 

Topamax can be used off-label, to treat nightmares associated with post-traumatic stress disorder. The starting dose is 25 mg, taken nightly for one week. Then, the dose can be increased by another 25 mg per day every week, until a dose of 75 mg per day is reached. 

• Standard adult dosage for nightmares associated with PTSD: 75 mg taken once per day at night 

• Maximum adult dosage for nightmares associated with PTSD: 75 mg taken once per day at night

Topamax for alcohol dependence 

Topamax is sometimes prescribed off-label for alcohol dependence because it can reduce alcohol cravings. The starting dose is 25 mg, taken once per day. The dose can be increased by 25 mg per day every week until a dose of 150 mg per day is reached. 

• Standard adult dosage for alcohol dependence: 100-150 mg taken once per day 

• Maximum adult dosage for alcohol dependence: 150 mg taken once per day 

RELATED: What happens when you mix Topamax and alcohol?

Topamax dosage for children

The FDA has approved Topamax for seizures among children ages 2 and older. Topamax for children is dosed based on their weight, but here are the minimum and maximum doses of Topamax for children of all ages: 

• Standard Topamax dosage for children ages 2 and above: dependent on weight, starting at 25 mg daily

• Maximum Topamax dosage for children ages 2 and above: 400 mg per day

Topamax is also approved for children 12 years of age and older to help prevent migraines. The baseline dose of Topamax for this group is 100 mg, taken in two divided doses. 

Topamax dosage restrictions

Topamax dosages are based on age and by weight among children younger than 10 years old. Aside from age and weight restrictions, people with certain contraindications may need to take a reduced dose of Topamax. Patients with renal impairment (kidney damage), for example, have an increased risk of reacting poorly to Topamax and may need to reduce their dose by up to 50%.

In addition to renally impaired patients, patients with one or more of the following should seek medical advice before taking Topamax because they may need an adjusted dose or they may not be able to take the medicine entirely:

• Metabolic acidosis (chemical imbalance)

• Acute myopia (sudden nearsightedness)

• Secondary angle-closure glaucoma 

• Lung disease or breathing problems

• High blood ammonia levels 

• Liver disease

• Mood problems 

• Growth disorders

• Soft or brittle bones

• Ketogenic diet 

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Women taking oral contraceptives should be aware that Topamax may cause decreased contraceptive efficacy and increased breakthrough bleeding. They may require different doses of Topamax compared to the average person or may need to discuss other drug options and alternative methods of contraception with their doctor. 

For women who are not taking birth control and may become or are pregnant, it’s important to note that Topamax can cause fetal harm when administered to pregnant women. If you’re pregnant and considering taking Topamax, it’s best to talk with your doctor about whether or not the drug is right for you. Clinical trials have also shown that Topamax passes from mothers to infants via breastmilk, but more research is needed to understand how it affects breastfeeding infants. Women who are pregnant or breastfeeding may require adjusted doses of Topamax for these reasons. 

Topamax dosage for pets

The generic version of Topamax, topiramate, isn’t approved by the FDA for use in animals, but it’s legal for veterinarians to prescribe it as an extra-label drug for seizure disorders in cats and dogs. Topiramate has been proven in clinical studies to be an effective add-on medication in treating canine idiopathic epilepsy (epilepsy from unknown causes). 

The exact dose of topiramate a dog or cat needs will vary depending on the animal and its unique medical condition. If your pet is having seizures, it’s best to talk with your veterinarian about whether or not topiramate could be helpful. 

How to take Topamax

Topamax is typically taken twice per day and can be taken with or without food. It’s important to take Topamax correctly to reduce the risk of experiencing side effects like:

• Tiredness

• Drowsiness

• Loss of appetite

• Blurred vision or eye problems

• Weight loss

• Cognitive dysfunction 

• Increased body temperature or hyperthermia

• Paresthesia (tingling of the arms and legs) 

• Somnolence (sleepiness)

• Suicidal thoughts 

• Kidney stones

Here’s how to take Topamax properly to avoid adverse reactions: 

• Take the medicine as directed in the medication guide. 

• Swallow the tablet whole and do not crush, chew, or break it.

• If you cannot swallow a capsule whole, open it and sprinkle the medicine into a spoonful of applesauce or other soft food. Swallow the mixture right away without chewing. Do not save it for later use. 

• Drink plenty of liquids while you are taking topiramate to prevent kidney stones and electrolyte imbalances. 

• Take the medicine for the full prescribed duration even if symptoms go away before the treatment has finished. 

• Do not miss a dose. A pharmacist can provide ideas and tools to avoid missed doses.

• Do not stop using topiramate suddenly, even if you feel fine. Sudden discontinuation may cause increased seizures.

• Store this medicine at room temperature (68 to 77 degrees Fahrenheit) in a tightly sealed and light-resistant container. 

Topamax dosage FAQs

Topamax vs. Trokendi XR: What’s the difference in dosage?

Topamax is usually taken in two divided doses because it’s processed by the body very quickly, but there’s an extended-release version of Topamax called Trokendi XR that only needs to be taken once per day. Both drugs are brand names but contain the same active ingredient, topiramate. 

Someone taking Topamax will likely take smaller doses of the drug twice per day, whereas someone taking Trokendi XR will likely take one larger dose once per day. The exact dosage will vary from person to person based on each individual's medical history and medical condition. 

RELATED: Learn more about Trokendi XR

How long does it take Topamax to work?

Topamax is a very effective drug, but it can take some time to start working. For people experiencing migraines, it may take one to three months to feel the effects of topiramate. However, people who take the drug for seizures may start seeing results within one to two weeks. 

Everyone who takes Topamax will react to it differently, so the amount of time it takes to see results can vary. Factors like a patient's body weight, level of physical activity, and diet can all affect how well the drug works. The best way to know how quickly Topamax may start working for you is to talk with a healthcare professional. 

How long does Topamax stay in your system?

Topamax has a half-life of about 21 hours which means that half of the drug will have left the body in that period. After your last dose, Topamax will remain in the bloodstream for four to six days. After that timeframe, it will have been eliminated from the body. 

What happens if I miss a dose of Topamax?

If you miss a dose of Topamax, take it as soon as you remember. Don’t take the missed dose if your next scheduled dose is due in less than six hours. Never take two doses at the same time because this can cause toxicity or overdose. 

How long can you take Topamax?

Topamax is usually prescribed long-term. It can take several months for the drug to start working and can be taken for many years as preventive medicine. 

What interacts with Topamax? 

Don’t take Topamax at the same time as certain medications because of the potential for drug interactions. Drug interactions can worsen the common side effects of Topamax or cause new side effects entirely. It’s best to talk with your doctor before taking Topamax if you take any of the following: 

• Metformin

• CNS depressants like alcohol.

• Antiepileptic drugs like phenytoin and carbamazepine.

• Valproate 

• Valproic acid 

• Carbonic anhydrase inhibitors like zonisamide and acetazolamide.

• Amitriptyline 

• Pioglitazone 

• Hydrochlorothiazide 

• Lithium

• Bupropion

• Metoclopramide 

• Oral contraceptives

Related resources for Topamax dosages:

• Topamax dosing for adults, Epocrates

• Topamax for mental health, National Alliance on Mental Illness

• Extra-label drug use, FDA

• Topiramate as a treatment for canine epilepsy, Journal of Small Animal Practice

• About Topamax for migraines, Janssen

• About topiramate, NHS

• Topiramate addiction, NOVA Recovery Center

• Topamax prescribing information, FDA