Amantadine is an antiviral medication used to prevent or treat certain influenza infections; it is also given as an adjunct for the treatment of Parkinson's disease. It has been demonstrated that this medication, through some unknown mechanism, is sometimes effective in relieving fatigue in multiple sclerosis.
The usual dosage for the management of fatigue in MS is 100 to 200 mg daily, taken in the earlier part of the day in order to avoid sleep disturbance. Doses in excess of 300 mg daily usually cause livedo reticularis, a blotchy discoloration of the skin of the legs.
The precautions listed here pertain to the use of this medication as an antiviral or Parkinson's disease treatment. There are no reports at this time concerning the precautions in the use of the drug to treat fatigue in multiple sclerosis.
- Drinking alcoholic beverages while taking this medication may cause increased side effects such as circulation problems, dizziness, lightheadedness, fainting, or confusion. Do not drink alcohol while taking this medication.
- This medication may cause some people to become dizzy, confused, lightheaded, or to have blurred vision or trouble concentrating.
- Amantadine may cause dryness of the mouth and throat. If your mouth continues to feel dry for more than two weeks, check with your physician or dentist since continuing dryness may increase the risk of dental disease.
- This medication may cause purplish red, net-like, blotchy spots on the skin. This problem occurs more often in females and usually occurs on the legs and/or feet after amantadine has been taken regularly for a month or more. The blotchy spots usually go away within two to twelve weeks after you stop taking the medication.
- Studies of the effects of amantadine in pregnancy have not been done in humans. Studies in some animals have shown that amantadine is harmful to the fetus and causes birth defects.
- Amantadine passes into breast milk. However, the effect of amantadine in newborn babies and infants is not known.
Possible Side Effects
The side effects listed here pertain to the use of amantadine as an antiviral or Parkinson's disease treatment. There are no reports at the present time of the side effects associated with the use of this drug in the treatment of MS-related fatigue.
Side effects that may go away as your body adjusts to the medication and do not require medical attention unless they continue or are bothersome: difficulty concentrating; dizziness; headache; irritability; loss of appetite; nausea; nervousness; purplish red, net-like, blotchy spots on skin; trouble sleeping or nightmares; constipation*; dryness of the mouth; vomiting.
Rare side effects that should be reported as soon as possible to your physician: blurred vision*; confusion; difficult urination*; fainting; hallucinations; convulsions; unusual difficulty in coordination*; irritation and swelling of the eye; mental depression; skin rash; swelling of feet or lower legs; unexplained shortness of breath.
*Since it may be difficult to distinguish between certain common symptoms of MS and some side effects of amantadine, be sure to consult your health care professional if an abrupt change of this type occurs.