Topiramate interactions to avoid

Drug interactions | Food interactions | Other interactions | Avoiding interactions | When to see a doctor

Topiramate is a prescription medication that was originally approved in 1996 by the U.S. Food and Drug Administration (FDA) to treat epilepsy and prevent various types of seizures. It is a carbonic anhydrase inhibitor and belongs to a family of prescription medicines called antiepileptic or anticonvulsant drugs. Following its introduction as an anticonvulsant, topiramate was later approved to help prevent migraine headaches and later still as an aid in weight loss. 

Topiramate is generic for the brand names Topamax, Eprontia, Qudexy XR, and Trokendi XR. Qsymia is the brand name for a weight loss drug that combines topiramate with phentermine. Dosage forms for topiramate include tablets, extended-release capsules, oral solutions, and sprinkle capsules.

While topiramate can be an effective treatment option for most people, there are potential drug interactions that may occur. These drug interactions can affect how topiramate works, or they can cause mild or even serious side effects. Some drugs that may interact with topiramate include other antiepileptic drugs, other carbonic anhydrase inhibitors, CNS depressants, estrogen-containing or progestin-only contraceptives, hydrochlorothiazide (HCTZ), diabetes drugs, lithium, amitriptyline, antihistamines, and alcohol. It is important to be aware of how topiramate may affect the action of other drugs and how other drugs (and foods) may affect topiramate. Continue reading to learn more about topiramate and its potential interactions. 

Topiramate drug interactions

There are several prescription and over-the-counter (OTC) drugs that can interact with topiramate. Some interactions may be mild, such as increasing the risk of side effects like dizziness or sleepiness, while others can be more serious, such as increasing the risk of developing kidney stones or reducing the effectiveness of oral contraceptives. Drug interactions may also adversely affect the blood levels of topiramate and reduce its effectiveness.

To avoid drug-drug interactions, be sure to discuss all of the prescription and OTC medications you take with your healthcare provider. 

Antiepileptic drugs

Antiepileptic drugs such as Tegretol (carbamazepine), Dilantin (phenytoin), Depakote (valproate), Lamictal (lamotrigine), Mysoline (primidone), valproic acid, and phenobarbital given at the same time may decrease the blood levels of topiramate in your body making it less effective. Concomitant use of Depakote (valproate) and topiramate can also raise the levels of ammonia in your blood, leading to side effects such as lethargy, vomiting, and mental changes such as confusion or disorientation.

Carbonic anhydrase inhibitors

When topiramate, a carbonic anhydrase inhibitor, is taken with another carbonic anhydrase inhibitor, such as Zonegran (zonisamide), methazolamide, or acetazolamide, it may increase the risk of kidney stone formation.

CNS depressants

Taking topiramate with medicines that are central nervous system (CNS) depressants, such as antianxiety agents (e.g., Xanax, Valium, or Ativan), sleeping medicines (e.g., Ambien, Halcion, or Restoril), opioid pain medicines (e.g., hydrocodone, oxycodone, or morphine), or alcohol, can cause excessive sedation and other symptoms of CNS depression such as muscle weakness, lethargy, dizziness, disorientation, or slurred speech..

Oral contraceptives

The possibility of decreased contraceptive efficacy and increased breakthrough bleeding may

occur in women taking estrogen-containing or progestin-only oral contraceptives with topiramate. To keep from getting pregnant, it is recommended to use an additional form of birth control (e.g., condoms or a diaphragm with spermicide) together with the birth control pill. 

Hydrochlorothiazide (HCTZ)

Taking hydrochlorothiazide and topiramate together may increase the blood levels of topiramate, causing an increased risk of side effects. If the two are taken together it may require a decrease in the topiramate dose.

Diabetes drugs

Taking metformin, a commonly prescribed oral antidiabetic drug and topiramate may increase the risk of side effects of both medications, including metabolic acidosis (a condition in which the fluids in your body have too much acid).

Taking topiramate with Glynase (glyburide) or Actos (pioglitazone) may cause them to be less effective in controlling blood sugar levels. It is recommended to monitor blood sugar levels when combining these drugs closely.

Lithium

Taking lithium, often prescribed for bipolar disorders, and topiramate together may increase the blood levels of both drugs, causing an increased risk of side effects. If the two are taken together it may require a decrease in the topiramate dose. Lithium blood levels should be monitored, especially when higher doses of topiramate are being taken. 

Amitriptyline

Combining topiramate and amitriptyline, a tricyclic antidepressant, may result in an increase in amitriptyline blood levels. Increased blood levels of amitriptyline may result in increased side effects such as drowsiness or dizziness. Adjustments may be made to either the topiramate or amitriptyline dose, depending on the clinical response to each drug.

Antihistamines

Certain OTC antihistamine drugs (e.g., diphenhydramine, chlorpheniramine, and hydroxyzine) may increase the risk of topiramate side effects such as dizziness, sleepiness, or trouble concentrating.

Topiramate food interactions

The absorption of topiramate into the bloodstream is not affected by food. Therefore, it can be taken with or without food. Because one of the most severe adverse effects of topiramate is metabolic acidosis, avoid eating a ketogenic diet or keto diet (high in fat, low in carbohydrates), which may increase the risk of higher acid levels in the blood.

Other topiramate interactions

There are potential non-drug interactions that may impact the effectiveness of topiramate or increase the risk of side effects. Any concerns or questions one may have about specific foods, OTC medications, vitamins, or herbal supplements should be discussed with a healthcare professional.

Topiramate and alcohol

Drinking alcohol while taking topiramate can increase the likelihood of experiencing the drug’s side effects. A combination of alcohol with topiramate can lead to excessive sleepiness, confusion, and difficulty speaking.

Topiramate and vitamins and supplements 

Taking high doses of vitamin C or calcium supplements with topiramate may increase the risk of developing kidney stones. St John’s wort, an herbal remedy for depression, may reduce the effectiveness of topiramate.

How to minimize topiramate interactions

Keep an updated list of all the pharmaceuticals, vitamins, and supplements you take and all your medical conditions. When starting topiramate, give this list to your healthcare provider and pharmacist. Your pharmacist can also provide a medication guide to give drug information and help avoid drug-drug interactions.

If you are already taking a medication that topiramate potentially interacts with, ask your healthcare provider for medical advice before making any changes to your drug regimen. Do not suddenly stop taking topiramate or any medicine without consulting your healthcare professional.

When to talk to a healthcare provider about topiramate interactions

This article lists various drug interactions but is not a complete list of all possible topiramate interactions. It is important that your healthcare provider be aware of all medications being taken (including prescription drugs, OTC medicines, vitamins, and supplements) to ensure proper management. 

Contact the prescribing healthcare provider immediately if any of the following symptoms occur while taking topiramate with another drug:

• Back or side pain or a burning sensation when you pee or observe cloudy or smelly pee—these may be signs of kidney problems or kidney stones
• Feeling sleepy, loss of appetite, and experiencing an irregular heartbeat—these may be signs of metabolic acidosis