Phentermine and topiramate is a combination medicine used together with diet and exercise to treat obesity in people 12 years and older.

This medicine is sometimes used to treat obesity that may be related to diabetes, high cholesterol, or high blood pressure. Phentermine and topiramate will not treat these underlying conditions. Keep using any other medicines your doctor has prescribed.

Phentermine and topiramate may also be used for purposes not listed in this medication guide.

Do not use this medicine if you have used an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. 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 have a negative pregnancy test before starting this treatment. Do not use phentermine and topiramate if you are pregnant. Stop taking this medicine and call your doctor right away if you become pregnant.

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

Taking this medicine together with birth control pills may cause breakthrough bleeding (spotting). However, this is unlikely to make your birth control pills less effective in preventing pregnancy. If you have spotting or irregular bleeding, keep 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 suicidal thoughts or actions;
• 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 cause growth problems in children or harm to an unborn baby. You may need blood tests to make sure you do not have metabolic acidosis.

Some people have thoughts about suicide while taking topiramate. Your doctor will need to check your progress at regular visits. Your family or other caregivers should also be alert to changes in your mood or symptoms.

You should not breastfeed while using this medicine.

Use Phentermine And Topiramate (Oral) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe 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: mood or behavior changes, 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 hurting yourself.

Call your doctor at once if you have:

• unusual changes in mood or behavior;
• confusion, trouble concentrating, problems with speech or memory;
• fast or pounding heartbeats while you are 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 may include:

• joint pain, ankle sprain;
• flu-like symptoms;
• dizziness;
• constipation;
• numbness or tingly feeling;
• sleep problems (insomnia);
• dry mouth, changes in your sense of taste; or
• mood changes, feelings of low self-worth, loss of interest in things you once enjoyed, thoughts about hurting 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 FDA at 1-800-FDA-1088.

Do not take other weight-loss products without your doctor's advice.

Ketogenic or "ketosis" diets that are high in fat and low in carbohydrates can increase the risk of metabolic acidosis. Avoid the use of such diets while you are taking this medicine.

Drinking alcohol with this medicine can cause side effects.

Avoid driving or hazardous activity until you know how this medicine will affect you. Your reactions could be impaired.

Avoid becoming overheated or dehydrated in hot weather. This medicine can decrease sweating and increase body temperature, leading to life-threatening dehydration.