What should I discuss with my healthcare provider before taking dextromethorphan and quinidine?
You should not take this medicine if you are allergic to dextromethorphan or quinidine, or if you have:
- heart failure;
- a history of life-threatening heart rhythm disorder;
- long QT syndrome (in you or a family member);
- a serious heart condition called "AV block" (unless you have a pacemaker); or
- if you also use mefloquine, quinidine, or quinine.
You also should not take dextromethorphan and quinidine if you have ever had any of the following problems caused by taking mefloquine, quinidine, or quinine:
- bruising or bleeding;
- hepatitis;
- an allergic reaction; or
- lupus-like symptoms (joint pain, fever, skin rash on your cheeks).
Do not use dextromethorphan and quinidine 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. After you stop taking dextromethorphan and quinidine, you must wait at least 14 days before you start taking an MAOI.
Dextromethorphan and quinidine can cause a serious heart problem. You should not take dextromethorphan and quinidine if you also use certain other medicines for infections, asthma, heart problems, high blood pressure, depression, mental illness, cancer, malaria, or HIV.
Be sure your doctor knows if you also take stimulant medicine, opioid medicine, herbal products, or medicine for depression, mental illness, Parkinson's disease, migraine headaches, serious infections, or prevention of nausea and vomiting. These medicines may interact with dextromethorphan and quinidine and cause a serious condition called serotonin syndrome.
Tell your doctor if you have ever had:
- heart disease, high blood pressure, coronary artery disease;
- slow heartbeats or any type of heart rhythm disorder;
- an electrolyte imbalance (such as low levels of potassium or magnesium in your blood);
- myasthenia gravis; or
- trouble with balance or walking.
Tell your doctor if you are pregnant or breastfeeding.
Dextromethorphan and quinidine is not approved for use by anyone younger than 18 years old.