Topamax is a type of prescription seizure medication known as an anticonvulsant. The U.S. Food & Drug Administration (FDA) first approved Topamax for treatment of epilepsy in 1996. The regulatory agency expanded the drug’s uses to include migraine prevention in 2004.
By 2007, Topamax controlled 21 percent of the $10.2 billion epilepsy drug market, according to Bloomberg News. Topamax sales reached $2.7 billion in 2008.
As Topamax gained popularity in the 2000s, people began to report startling side effects. As a result, the FDA added several warnings to the drug’s label, including increased risks for high levels of acid in the blood, eye disorders that could lead to permanent vision loss, and suicidal thoughts and behaviors.
Topamax lost its patent protection in 2009, and sales dropped to $1.15 billion. In 2011, the agency warned of Topamax’s link to birth defects and injured users began suing the drug’s manufacturer. Also in 2011, J&J recalled 57,000 bottles of Topamax because of possible chemical contamination.
Today, Janssen continues to sell Topamax in the U.S. at a price of nearly $100 for sixty 15 mg oral capsules.
FDA-Approved Topamax Uses
When Topamax first hit the market, the FDA limited the drug for use in treating epileptic symptoms. After about eight years, the agency added migraine prevention as an FDA-approved use. Seizures and migraines continue to be the only government-approved uses for Topamax in the U.S.
During a seizure, brain cells are forced to work much faster than they normally would. Topamax is designed to stop seizures when they first begin by preventing brain cells from working in overdrive.
Topamax gained FDA approval in 1996 for treatment of epilepsy, a neurological disorder characterized by recurrent, uncontrolled seizures. Doctors also prescribe the medicine for patients 2 years or older whose seizures are associated with Lennox-Gastaut syndrome, a disorder that accounts for up to 10 percent of all cases of childhood epilepsy. Topamax is not approved for use in children younger than 2 years of age.
The FDA approved Topamax for use by itself or with other medications to treat:
- Partial onset seizures
- Primary generalized tonic-clonic seizures
- Seizures associated with Lennox-Gastaut syndrome
In 2004, the FDA approved Topamax for the prevention of migraine headaches in people 12 years of age and older. Topamax does not relieve the pain of a migraine after it starts, but it is believed to reduce migraine frequency by calming overactive pain-signal firing in nerve cells.
Topamax’s manufacturers recommend doctors “start low and grow slow” when prescribing Topamax. This means a doctor will likely prescribe a low dose to start and then slowly increase the amount of Topamax a patient takes until reaching the dosage that works best for the patient.
The Right Topamax Level
It takes time for Topamax to build up to the right level in the bloodstream. It may take two to three months of daily Topamax use for the medication to start working.
Off-Label Use for Weight Loss, Psychiatric Disorders
Topamax is also used to control binging and purging, and to promote weight loss. However, this is not an FDA-approved use. Although it is illegal for drug makers to promote drugs for off-label uses, doctors can legally prescribe any drug they consider appropriate to treat a patient’s condition.
Topiramate, the active ingredient in Topamax, is also a main ingredient in the weight-loss drug Qsymia. The FDA approved Qsymia in 2012. A year earlier, the same drug — then called Qnexa — was rejected by the FDA because of the adverse side effects of its topiramate component.
The FDA label warns Qsymia may cause mood and sleep disorders, cognitive impairment and increased heart rate. It could also lead to suicidal thoughts, and people who suddenly stop taking it can suffer seizures.
In addition to weight loss, Topamax has also been used — and illegally marketed — to treat:
- Bipolar disorder
- Alcohol dependency
- Cocaine and methamphetamine addiction
- Obsessive-compulsive disorder
- Borderline personality disorder
- Post-traumatic stress disorder
Topamax Side Effects
Janssen maintains that Topamax is safe when used as indicated. The drug has a number of common side effects, which its manufacturer claims to be “mild to moderate.” One common side effect of the drug is somnolence, or sleepiness. Some doctors and patients have dubbed the drug “Sleepomax” because of its heavy sedative effects.
Commonly reported side effects with Topamax include:
- Weight loss
- Upper respiratory tract infection
- Burning or prickling in the hands, arms, legs and feet (paresthesia)
- Psychomotor slowing
- Loss of appetite
- Taste change
- Speech disorders/related speech problems
- Abdominal pain
- Numbness (hypoesthesia)
- Abnormal vision
- Difficulty with memory
Over the years, post-market studies have revealed several much more serious health risks associated with Topamax. In response, the FDA has continually mandated that all topiramate labels and medication guides contain updated warnings and precautions associated with its use.
Timeline of FDA Topamax Warnings:
FDA required a warning about metabolic acidosis (an increase in the level of acid in the blood); oligohydrosis (decreased sweating); and hyperthermia (increased body temperature)
FDA required a warning about serious eye disorders, such as acute myopia and secondary angle closure glaucoma, which can lead to permanent visual loss
FDA required a warning about increased risk of suicidal thoughts and behaviors
FDA required a warning about the risks of oral birth defects and changed Topamax’s classification from pregnancy category “C” to “D,” which means there is evidence of fetal risk among humans
Topamax’s label also includes warnings for confusion, psychomotor slowing, difficulty with concentration/attention, and difficulty with memory, speech or language problems (difficulty finding words). Other Topamax side effects include depression or mood problems; excess of ammonia in the blood; brain disease that alters brain function or structure; kidney stones and hypothermia.
Topamax Drug Interactions
Topamax is known to interact with other substances in a way that can be dangerous for patients. The body digests Topamax in the liver and eliminates it from the body through the kidneys. Taking other medicines that are digested in liver at the same time as Topamax may affect how quickly the drug works and leaves the body. People with liver disease and people with a history of kidney stones must be cautious about taking the drug.
Birth control pills may not prevent pregnancy in women who also take Topamax.
The body gets rid of Topamax faster if taken at the same time as certain seizure medicines, including carbamazepine (Tegretol, Tegretol XR, Carbatrol), phenytoin (Dilantin, Phenytek), phenobarbital and primidone. Taking Topamax with valporic acid (Depakote and Depakene) has been associated with hypothermia and hyperammonemia.
Topamax makes birth control pills less effective, so the chances of becoming pregnant while on Topamax are greater. If a woman takes Topamax while pregnant, her baby has a higher risk for birth defects called clef lip and cleft palate.
People should not drink alcohol or take sedatives or tranquilizers, such as Valium, Xanax, while taking Topamax. Topamax suppresses the activity of carbonic anhydrase in the body. Using the drug with any other carbonic-anhydrase inhibitor (zonisamide or acetazolamide) may increase the severity of metabolic acidosis and may also increase the risk of kidney stone formation. Topamax also interacts with lithium.
Emily Miller holds five Health Literacy certificates from the Centers for Disease Control and Prevention as well as a Bachelor of Science in Journalism from the University of Florida. She is a member of The Alliance of Professional Health Advocates and the American Association for the Advancement of Science. Emily was diagnosed with a chronic illness as a child and has firsthand experience with many of the topics she writes about as a member of the Drugwatch team. She is an award-winning journalist who has reported on health and legal news for reputable organizations, including the South Florida Sun Sentinel, San Antonio Express-News, UF Health News and Reporters Committee for Freedom of the Press. She draws on her background as both a patient and a journalist to help readers understand complex health and legal topics.