Phentermine and topiramate

Phentermine and topiramate is a combination medicine that is used along with diet and exercise to treat obesity in people who are 12 years old and older.

Phentermine and topiramate can sometimes be used to treat obesity that may be linked to diabetes, high cholesterol, or high blood pressure. Phentermine and topiramate will not treat these underlying conditions. Continue taking any other medicines your doctor has prescribed.

Phentermine and topiramate may also be used for reasons not mentioned in this medication guide.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Take phentermine and topiramate each morning, with or without food.

Drink plenty of water each day to prevent dehydration or kidney stones while you are taking phentermine and topiramate.

Your doctor may change your dose or tell you to stop taking this medicine if you have not lost a certain amount of weight during the first 12 weeks. Follow your doctor's dosing instructions very carefully. You must also follow a low-calorie diet.

Do not stop using phentermine and topiramate suddenly or you could have a seizure (convulsions). Follow your doctor's instructions about tapering your dose.

Phentermine and topiramate can increase your resting heart rate. Your doctor will need to check your heart function.

Store at room temperature away from moisture and heat.

Phentermine may be habit-forming. Misuse can cause addiction, overdose, or death. Keep the medication in a place where others cannot get to it. Selling or giving away this medicine is against the law.

Do not use if you are pregnant or if you become pregnant. Phentermine and topiramate may increase the risk of a birth defect called cleft lip and palate in a newborn.

Phentermine and topiramate can increase your resting heart rate. Tell your doctor if you have fast or pounding heartbeats while you are resting.

Topiramate may cause vision problems that can be permanent if not treated quickly. Call your doctor right away if you have a sudden decrease in vision.

Some people have thoughts about suicide while taking topiramate. Stay alert to changes in your mood or symptoms. Report any new or worsening symptoms to your doctor.

Do not use this medicine if you have taken an MAO inhibitor in the past 14 days. A dangerous interaction could happen. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, tranylcypromine, and others.

You should not use this medicine if you are allergic to phentermine or topiramate, or if you have:

• glaucoma;
• overactive thyroid; or
• if you are pregnant or may become pregnant.

You may need to take a pregnancy test before starting this treatment. Do not use phentermine and topiramate if you are pregnant. Stop taking this medicine and call your doctor immediately if you become pregnant.

Topiramate may increase the risk of cleft lip and palate in a newborn. This birth defect can happen early in pregnancy, even before you know you are pregnant. Losing weight during pregnancy can also harm an unborn baby, even if you are overweight. Use effective birth control to prevent pregnancy while using phentermine and topiramate.

Taking this medicine with birth control pills may cause breakthrough bleeding (spotting). However, this is unlikely to make your birth control pills less effective. If you have spotting or irregular bleeding, continue taking your birth control pills and talk with your doctor.

Tell your doctor if you have ever had:

• heart problems, high blood pressure;
• a heart attack or stroke;
• diabetes (weight loss may cause low blood sugar);
• metabolic acidosis (too much acid in your blood);
• soft or brittle bones (osteomalacia, osteopenia, osteoporosis);
• kidney disease, kidney stones, or dialysis;
• liver disease;
• mood problems, depression, or thoughts or actions of suicide;
• an allergy to aspirin or yellow dye (tartrazine);
• a seizure; or
• chronic diarrhea.

Topiramate can increase the level of acid in your blood (metabolic acidosis). This can weaken your bones, cause kidney stones, or lead to growth problems in children or harm to an unborn baby. You may need blood tests to ensure you do not have metabolic acidosis.

Some people may have thoughts about suicide while taking topiramate. Your doctor will need to monitor your progress during regular visits. Your family or other caregivers should also be aware of any changes in your mood or symptoms.

You should not breastfeed while using this medicine.

Get emergency medical help if you notice signs of an allergic reaction (hives, difficulty breathing, swelling in your face or throat) or a serious skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Report any new or worsening symptoms to your doctor, such as: changes in mood or behavior, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), depressed, or have thoughts about suicide or harming yourself.

Phentermine and topiramate may cause serious side effects. Call your doctor immediately if you have:

• unusual changes in mood or behavior;
• confusion, trouble concentrating, problems with speech or memory;
• fast or pounding heartbeats while resting;
• a seizure;
• signs of a kidney stone--severe pain in your side or lower back, painful or difficult urination; or
• signs of too much acid in your blood--loss of appetite, tiredness, thinking problems, irregular heartbeats.

Common side effects of phentermine and topiramate may include:

• joint pain, ankle sprain;
• flu-like symptoms;
• dizziness;
• constipation;
• numbness or tingling;
• sleep problems (insomnia);
• dry mouth, changes in your sense of taste; or
• mood changes, feelings of low self-worth, loss of interest in activities you once enjoyed, thoughts about harming yourself.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Skip the missed dose and take your next dose at the usual time. Do not take two doses at the same time.

Seek emergency medical help or call the Poison Help line at 1-800-222-1222. Taking too much phentermine and topiramate can be deadly.

Signs of an overdose may include confusion, hallucinations, panic, changes in personality, tremors, feeling restless followed by extreme tiredness, nausea, vomiting, diarrhea, stomach cramps, an irregular heartbeat, rapid breathing, seizures, or coma.

Do not use other weight-loss products unless your doctor tells you to.

Ketogenic or "ketosis" diets that are high in fat and low in carbohydrates can raise the risk of metabolic acidosis. Avoid these diets while taking phentermine and topiramate.

Drinking alcohol with this medicine can lead to side effects.

Avoid driving or engaging in dangerous activities until you know how this medicine affects you. Your reactions may be affected.

Avoid getting too hot or dehydrated in warm weather. This medicine can reduce sweating and raise body temperature, which can lead to serious dehydration.

Phentermine and topiramate can cause irregular vaginal bleeding while you are taking birth control pills. This should not make the pills less effective in preventing pregnancy.

Using this medicine with other drugs that make you drowsy can worsen this effect. Ask your doctor before using opioid medication, a sleeping pill, a muscle relaxer, or medicine for anxiety or seizures.

Tell your doctor about all your other medicines, especially:

• acetazolamide;
• methazolamide;
• zonisamide;
• valproic acid or divalproex sodium (Depakene or Depakote);
• birth control pills;
• a diuretic or "water pill"; or
• insulin or oral diabetes medicine.

This list is not complete. Other drugs may affect phentermine and topiramate, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.