Interferon Also indexed as: Actimmune, Alferon N, Avonex, Betaseron, Infergen, Intron, Rebif, Roferon-A, Wellferon
Interferons are proteins made by the human immune system for fighting viral infections and regulating cell function. Three types of interferons are used as drugs: interferon alpha, interferon beta, and interferon gamma. They are used by injection to treat viral infections, hepatitis, multiple sclerosis, some cancers, and other diseases.
The information in this article pertains to interferon in general. The interactions reported here may not apply to all the Also Indexed As terms. Talk to your doctor or pharmacist if you are taking any of these drugs.
Summary of Interactions with Vitamins, Herbs, and Foods
In some cases, an herb or supplement may appear in more than one category, which may seem contradictory. For clarification, read the full article for details about the summarized interactions.
 May Be Beneficial: Side effect reduction/prevention—Taking these supplements may help reduce the likelihood and/or severity of a potential side effect caused by the medication. | Thymus peptides* |
| May Be Beneficial: Supportive interaction—Taking these supplements may support or otherwise help your medication work better. | Licorice* N-acetyl cysteine (NAC)* Thymus peptides* |
 Avoid: Reduced drug absorption/bioavailability—Avoid these supplements when taking this medication since the supplement may decrease the absorption and/or activity of the medication in the body. | Thymus peptides* |
| Avoid: Adverse interaction—Avoid these supplements when taking this medication because taking them together may cause undesirable or dangerous results. | Bupleurum |
| Depletion or interference | None known |
An asterisk (*) next to an item in the summary indicates that the interaction is supported only by weak, fragmentary, and/or contradictory scientific evidence.
Interactions with Dietary Supplements
N-acetyl cysteine (NAC)
One preliminary trial found that adding 600 mg NAC three times per day to interferon therapy for people with chronic hepatitis C led to improvement in their conditions not seen with interferon alone.1 However, other preliminary2 3 and double-blind trials4 5 have failed to confirm the efficacy of this approach. At the present time, sufficient evidence is lacking to support the use of this drug-nutrient combination in persons with hepatitis.
Thymus peptides
Peptides or short proteins derived from the immune organ known as the thymus gland have been investigated in combination with interferon therapy for people with hepatitis B and C. One study found that adding thymus humoral factor-gamma 2 to interferon therapy prevented decreases in white blood cell counts sometimes seen with interferon alone, and also seemed to improve the efficacy of interferon against hepatitis B.6 Thymus humoral factor-gamma 2 must be administered by injection, requiring consultation with a doctor. It is not known whether orally administered thymus extracts would be useful in combination with interferon.
Interactions with Herbs
Bupleurum (Bupleurum chinense)
Bupleurum is the major constituent of a Japanese Kampo (herbal) medicine formula called sho-saiko-to. This formula has been used alone or with interferon to treat hepatitis. Eighty or more cases of drug-induced pneumonitis (inflammation of the lungs) have been associated with the use of sho-saiko-to alone or with interferon.7 8 9 10 Until more is known, sho-saiko-to should not be combined with interferon.
Licorice (Glycyrrhiza glabra)
Injections of the licorice compound glycyrrhizin are commonly used to treat hepatitis in Japan. The combination of glycyrrhizin and interferon may be more effective than interferon alone.11 12 Injectable glycyrrhizin is available from some physicians. So far, human studies have not used orally administered licorice extracts in conjunction with interferon.
References (To view, roll mouse over the "References" heading; to hide, click on the heading)
1. Beloqui O, Prieto J, Sua’rez B, et al. N-Acetyl cysteine enhances the response to interferon-alpha in chronic hepatitis C: A pilot study. J Interferon Res 1993;13:279–82.
2. Look MP, Gerard A, Rao GS, et al. Interferon/antioxidant combination therapy for chronic hepatitis C--a controlled pilot trial. Antiviral Res 1999;43:113–22.
3. Cimino L, Belisario MA, Intrieri M, et al. Effect of N-acetyl-cysteine on lymphomonocyte glutathione and response to interferon treatment in C-virus chronic hepatitis. Ital J Gastroenterol Hepatol 1998;30:189–93.
4. Grant PR, Black A, Garcia N, et al. Combination therapy with interferon-alpha plus N-acetyl cysteine for chronic hepatitis C: a placebo controlled double-blind multicentre study. J Med Virol 2000;61:439–42.
5. Ideo G, Bellobuono A, Tempini S, et al. Antioxidant drugs combined with alpha-interferon in chronic hepatitis C not responsive to alpha-interferon alone: a randomized, multicentre study. Eur J Gastroenterol Hepatol 1999;11:1203–7.
6. Farhat BA, Marinos G, Daniels HM, et al. Evaluation of efficacy and safety of thymus humoral factor-gamma 2 in the management of chronic hepatitis B. J Hepatol 1995;23:21–7.
7. Nakagawa A, Yamaguchi I, Takao T, Amano H. Five cases of drug-induced pneumonitis due to sho-saiko-to or interferon alpha or both. Nippon Kyobu Shikkan Gakkai Zasshi 1995;33:1361–6 [in Japanese].
8. Ishizaki T, Sasaki F, Ameshima S, et al. Pneumonitis during interferon and/or herbal drug therapy in patients with chronic active hepatitis. Eur Respir J 1996;9:2691–6.
9. Sugiyama H, Nagai M, Kotajima F, et al. A case of interstitial pneumonia with chronic hepatitis C following interferon-alpha and sho-saiko-to therapy. Arerugi 1995;44:711–4 [in Japanese].
10. Sato A, Toyoshima M, Kondo A, et al. Pneumonitis induced by the herbal medicine Sho-saiko-to in Japan. Nippon Kyobu Shikkan Gakkai Zasshi 1997;35:391–5 [in Japanese].
11. Fujisawa K. Interferon therapy in hepatitis C virus (HCV) induced chronic hepatitis: Clinical significance of pretreatment with glycyrhizine. Trop Gastroenterol 1991;12:176–9.
12. Abe Y, Ueda T, Kato T, et al. Effectiveness of interferon, glycyrrhizin combination therapy in patients with chronic hepatitis C. Nippon Rinsho 1994;52:1817–22 [in Japanese].
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The information presented in Healthnotes is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2009.