Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.
Dizziness/reduced alertness: Dizziness, a disturbed sense of balance, and other problems with the nervous system have been reported during and up to 3 weeks after the use of mefloquine. Use caution when performing tasks requiring mental alertness and coordination (such as driving or operating machinery).
Drug interactions: Taking mefloquine at the same time as other medications, including quinine, quinidine, and chloroquine, may cause heart rhythm problems, cardiac arrest, or increase the risk of seizures. Do not take these medications at the same time as mefloquine. Halofantrine and ketoconazole may affect the electrical activity of the heart and cause QT prolongation. Do not take halofantrine or ketoconazole while taking melfoquine for the prevention or treatment of malaria, or for 15 weeks after the last dose of mefloquine.
Heart conditions: Mefloquine can cause heart rhythm problems. If you develop an abnormal or irregular heartbeat or palpitations while taking mefloquine to prevent malaria, contact a doctor as soon as possible. If you have heart rhythm problems, you should discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.
Liver disease: People with liver disease may experience higher blood levels of this medication. If you have liver disease, talk to your doctor about the benefits and risks of using this medication.
Mental problems: Some people taking mefloquine may experience psychiatric symptoms (including depression, generalized anxiety disorder, paranoia, hallucinations, and psychotic behaviour). In rare cases, they may have thoughts of suicide. If you have a history of psychiatric disturbances (including depression, generalized anxiety disorder, schizophrenia, or other major psychiatric disorders), you should not take this medication.
If you are taking mefloquine to prevent malaria and you experience a sudden onset of anxiety, depression, restless or irritability, or confusion (which are possible signs of more serious mental problems), contact a doctor or health care provider as soon as possible. You may need to stop taking mefloquine and use another malaria prevention medication instead.
Seizure disorder: Mefloquine may increase the risk of seizures in people who have epilepsy. People with a history of seizures should not take mefloquine to prevent malaria, and should only take mefloquine to treat malaria only if the benefits outweigh the risks.
Stopping the medication: If you are told by a doctor or other health care provider that you need to stop taking mefloquine because of side effects or other reasons, you will need to take another malaria prevention medication. Leave the malaria area if you cannot get another medication. However, leaving the malaria area may not protect you from getting malaria; you still need to take a malaria prevention medication.
Pregnancy: If possible, it is best if pregnant women avoid travelling to areas where they risk malaria exposure. This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately. Women of childbearing age should use reliable birth control while taking mefloquine and for 3 months after the last dose has been taken.
Breast-feeding: This medication passes into breast milk. If you are a breast-feeding mother and are taking mefloquine, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.
Children: The safety and effectiveness of using this medication have not been established for children less than 3 months old or weighing less than 5 kg.