Interferon-α (IFN-α) has been extensively explored for its efficacy in various disease conditions and is currently used as a standard treatment in several of these. Its use is accompanied by a wide variety of possible side effects. These side-effects may hamper reaching and maintaining the dose needed for maximal therapeutic effect while their occurrence can outweigh clinical benefit of IFN-α treatment. This review addresses the toxicity profile of IFN-α, the presumed pathophysiology of the different side effects and the strategies to handle these.

Computerized searches were used and cross-references of articles and books were checked.

Adverse effects due to IFN-α have been described in almost every organ system. Many side-effects are clearly dose-dependent. Taken together, occurrence of flu-like symptoms, hematological toxicity, elevated transaminases, nausea, fatigue, and psychiatric sequelae are the most frequently encountered. Although insight in the mechanisms accounting for IFN-α-related toxicities has improved in recent years, much remains to be elucidated. Guidelines on the management of these untoward sequelae are mostly based on clinical experience, while many side-effects can only be adequately handled by dose adjustment or cessation of treatment.

Further research on the mechanisms underlying both therapeutic effects and adverse events is warranted. Hopefully, this will lead to better identification of those patients who are likely to benefit from treatment without experiencing severe toxicities.