When This Medicine Should Not Be Used:
You should not use this medicine if you have had an allergic reaction to dextromethorphan or quinidine, or if you are using this medicine together with other products containing quinidine, quinine (Qualaquin®), or mefloquine (Lariam®). Do not use this medicine if you have a history of bone marrow problems, hepatitis, lupus-like syndrome, or thrombocytopenia (low platelets in the blood) caused by quinidine, quinine, or mefloquine. You should not use this medicine if you have a heart block without a pacemaker, heart failure, or heart rhythm problems (such as congenital long QT syndrome, prolonged QT interval, or a history of torsade de pointes). Do not use this medicine if you are also using medications such as pimozide (Orap®) or thioridazine (Mellaril®), or an MAO inhibitor (MAOI) such as Eldepryl®, Marplan®, Nardil®, or Parnate® within the past 14 days.

How to Use This Medicine:
Capsule

• Your doctor will tell you how much medicine to use. Do not use more than directed.

Drugs and Foods to Avoid:
Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

• Because of the potential for drug interactions with this medication, it is very important to tell your doctor about anything (over-the-counter or prescription) that you are using.
• Do not eat grapefruit or drink grapefruit juice while you are using this medicine.
• Tell your doctor if you use anything else that makes you sleepy. Some examples are allergy medicine, narcotic pain medicine, and alcohol.
• Do not drink alcohol while you are using this medicine.

Warnings While Using This Medicine:

• Make sure your doctor knows if you are pregnant or breastfeeding, have liver or kidney problems, heart or blood vessel disease, high blood pressure, low potassium or magnesium in the blood, myasthenia gravis (severe muscle weakness), or a history of stroke. Tell your doctor if you have been addicted to drugs or alcohol.
• Stop using this medicine and check with your doctor right away if you have the following symptoms while taking this medicine: black, tarry stools; bleeding gums; blood in the urine or stools; chills; fever; lightheadedness; nausea or vomiting; pinpoint red spots on the skin; or unusual bleeding or bruising.
• This medicine can cause changes in heart rhythms, such as a condition called QT prolongation. It may change the way your heart beats and cause fainting or serious side effects in some patients. Contact your doctor right away if you have any symptoms of heart rhythm problems, such as fast, pounding, or irregular heartbeats.
• This medicine may make you dizzy or drowsy. Avoid driving, using machines, or doing anything else that could be dangerous if you are not alert.
• Make sure your doctor knows about all the other medicines you are using. This medicine may cause a serious condition called serotonin syndrome when it is taken with certain medicines.
• Call your doctor if your symptoms do not improve or if they get worse.
• Your doctor will check your progress and the effects of this medicine at regular visits. Keep all appointments. Blood tests may be needed to check for unwanted effects.

Possible Side Effects While Using This Medicine:
Call your doctor right away if you notice any of these side effects:

• Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
• Agitation, confusion, poor coordination, restlessness, or trembling or shaking.
• Change in how much or how often you urinate, painful or difficult urination.
• Fast, pounding, or uneven heartbeat.
• Fever, chills, cough, sore throat, and body aches.
• Rapid weight gain.
• Shortness of breath, tiredness, and yellowing of your skin or the whites of your eyes.
• Swelling in your hands, ankles, or feet.
• Swollen, painful, or tender lymph glands in your neck, armpit, or groin
• Unusual bleeding, bruising, or weakness.

If you notice these less serious side effects, talk with your doctor:

• Diarrhea, gas, nausea, or vomiting.
• Dizziness.
• Weakness.

If you notice other side effects that you think are caused by this medicine, tell your doctor.
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088