Successes and Drawbacks. Interferons can reduce flare-ups overall by 30% and have an even greater effect on reducing major relapses. Disease activity, as measured by MRI scanning, is reduced by over 80%. They appear to be about equal in reducing disability. To date, only Avonex has demonstrated slowing progression of mental impairment. It also appears to be better tolerated than other interferons. Studies on their effects on quality of life are limited. None of the interferons is a cure, in any case, and when the drug is discontinued, disease activity may increase. All of these drugs need to be injected. (Oral forms are under investigation.)
Side Effects and Complications. Side effects include:
- Pain at the injection site. Many patients taking Betaseron complain of severe pain at the injection site caused by damaged tissue. Experts recommend taking acetaminophen (Tylenol) before the injection and then every 6 hours after each injection for 24 hours during the first 6 months of treatment.
- Skin injury at the injection site. Black dead tissue may form around the site, and many patients taking Betaseron have reported severe skin eruptions. These skin injuries heal after the drug is withdrawn, but scarring can occur. This side effect is least severe with Avonex, followed by Rebif.
- Other physical side effects. Both drugs cause flu-like symptoms, nausea, vomiting, headaches, and dizziness. Such side effects usually fade after 2 to 3 months.
- Depression. Early studies associated taking interferon with a higher risk for depression during the first 2 to 6 months following initial therapy. More recent studies, however, have reported no greater risk for depression in patients taking any of these drugs. MS itself, in any case, is highly associated with depression.
- Thyroid abnormalities. Interferon has been associated with autoimmune thyroiditis, a cause of hypothyroidism. Some experts recommend monitoring for thyroid function, particularly in the first year and in those with a history of thyroid problems. If there is no evidence of the condition during that period, the risk for its occurrence appears to be very low.
- Liver damage. Interferon may cause liver damage and, in rare cases, liver failure. Patients should avoid alcohol and have regular liver function tests while taking this drug
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