How does this medication work? What will it do for me?
Mefloquine belongs to the class of medications called antimalarials. Mefloquine is used to treat and prevent malaria infections caused by certain types of parasites.
Malaria is an infection caused by a group of parasites called Plasmodia that enter the blood through bites from infected mosquitoes. The parasites first enter and destroy red blood cells, then they reproduce within the liver and are released into the blood. Mefloquine does not prevent the mosquitoes from biting or prevent the parasite from reproducing in the liver. Mefloquine works by destroying the parasite after it is released from the liver into the blood.
This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.
Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.
Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.
What form(s) does this medication come in?Each white, round, biconvex tablet, cross scored on one side, and plain on the other side, contains 250 mg mefloquine (base) as mefloquine hydrochloride. Nonmedicinal ingredients: microcrystalline cellulose, magnesium stearate, croscarmellose sodium, and colloidal silicon dioxide.
How should I use this medication?
The recommended preventative dose of mefloquine is 250 mg once a week. This medication should be taken on the same day of the week for the following time period:
- one week before arrival in a malaria area (to allow blood levels of the medication to be effective)
- throughout your stay in this area
- 4 weeks after leaving the area (in case you have been infected and the parasite is reproducing in the liver)
For people who weigh less than 45 kg (99 lbs), your doctor will adjust the dose of mefloquine according to your body weight.
The dose of mefloquine for treatment of malaria is based on body weight (20 mg/kg to 25 mg/kg for those with no immunity, and 15 mg/kg for those with partial immunity). The total dose is taken all at once or in 2 to 3 doses spaced 6 or 8 hours apart to reduce the occurrence or severity of side effects. If a person vomits less than 30 minutes after receiving the medication, a full additional dose should be taken as instructed by your doctor. If vomiting occurs 30 to 60 minutes after the dose, an additional one-half dose should be taken as instructed by your doctor.
Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.
Mefloquine should be taken with food (e.g., any meal) and with plenty of water (at least 240 mL, equivalent of 1 cup [8 ounces]). Do not chew the tablets, but you may crush and mix them with a small amount of water, milk, or other beverage.
It is very important to take this medication exactly as prescribed by your doctor. Do not take a double dose. For missed doses intended for prevention of malaria, take the dose as soon as you remember and take each remaining dose according to the weekly dosing schedule, counting from the day you took the missed dose. Do not take more than one dose in a week.
Immediately contact a doctor if you suspect that you have contracted malaria. Your doctor may recommend a self-treatment plan if you cannot get to a doctor within 12 to 24 hours.Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.
Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.
Who should NOT take this medication?
Mefloquine should not be taken to prevent malaria by anyone who:
- is allergic to mefloquine or to any of the ingredients of the medication
- is allergic to related medications (e.g., quinine, quinidine, chloroquine)
- is taking any of the following medications:
- has a history of psychiatric disturbances (including depression, generalized anxiety disorder, schizophrenia, or other major psychiatric disorders)
- has a history of seizures
What side effects are possible with this medication?
Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.
The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.
Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.
- abdominal pain
- abnormal dreams
- loss of appetite
- trouble sleeping
Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.
Check with your doctor as soon as possible if any of the following side effects occur:
- irregular heartbeat or palpitations
- mood or mental changes
- muscle aches or pain
- ringing in the ears
- severe or continuing headache
- skin rash
- unexplained anxiety
- unusual tiredness or weakness
Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.
Are there any other precautions or warnings for this medication?
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.
What other drugs could interact with this medication?
There may be an interaction between mefloquine and any of the following:
If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:
- stop taking one of the medications,
- change one of the medications to another,
- change how you are taking one or both of the medications, or
- leave everything as is.
An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.
Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.