The thymus gland is found behind the sternum in the middle of the chest. It plays a significant role in the immune system, especially in unborn and very young children. The theory behind the use of thymus extracts is that they might stimulate or normalize immunity. However, there is no reliable real evidence as yet that any thymus extracts are effective for any health condition. Furthermore, there are significant safety concerns with thymus products.
Thymus extract is produced primarily from the thymus gland of cows. This has led to concerns regarding "mad cow" disease. All the studies described below used a pharmaceutical-grade form of thymus called Thymomodulin. It is not known whether the thymus supplements available as a dietary supplement would have the same effect.
The dosage of thymus extract used in studies has varied widely, depending on the particular thymus product used.
Two double-blind placebo-controlled trials enrolling children with frequent respiratory infections, such as colds, found that treatment with thymus extract reduced the rate of infection.1,18 In theory, this might indicate an immune-boosting effect. However, small studies cannot provide reliable proof that a treatment is effective. Weak evidence from a rather convoluted trial hints that thymus extract may also be helpful for preventing respiratory infections in adults.19
Intensive athletic training can suppress immune function and lead to colds, as well. However, a double-blind, placebo-controlled trial of 60 athletes failed to find any significant evidence of benefit with thymus extract.2
Preliminary evidence hints that thymus extracts may be helpful for food allergies,3asthma,4,20hay fever,21 and eczema. If thymus extract really does help these conditions, it may do so not by boosting the immune system, but rather by calming it down and causing it to behave more normally.
Injectable forms of whole thymus extract or chemicals contained in it have been studied as a treatment for numerous other conditions, including cancer, cold sores, dermatomyositis, eczema, genital warts, hepatitis, HIV infection, leukopenia (low white cell count), multiple sclerosis, psoriasis, respiratory infections, rheumatoid arthritis, scleroderma, and shingles (herpes zoster).9-16
The results of these studies have been mixed. In any case, trials involving injected thymus cannot be considered applicable to oral thymus products.
Thymus extracts have not been definitely associated with any side effects. However, there are real concerns that any glandular extract might contain the virus causing "mad cow disease."17 Keep in mind that there is relatively little governmental regulation of thymus products sold as dietary supplements in the US. Even when a ban is placed on importation of cow glands from a country where mad cow disease has been found, the ban does not apply to dietary supplements! For this reason, we recommend that you do not use thymus products sold as dietary supplements unless they are certified as free from risk of infection.
1. Fiocchi A, Borella E, Riva E, et al. A double-blind clinical trial for the evaluation of the therapeutical effectiveness of a calf thymus derivative (Thymomodulin) in children with recurrent respiratory infections. Thymus. 1986;8:331-339.
2. Garagiola U, Buzzetti M, Cardella E, et al. Immunological patterns during regular intensive training in athletes: quantification and evaluation of a preventive pharmacological approach. J Int Med Res. 1995;23:85-95.
3. Cavagni G, Piscopo E, Rigoli E, et al. Food allergy in children: an attempt to improve the effects of the elimination diet with an immunomodulating agent (thymomodulin). A double-blind clinical trial. Immunopharmacol Immunotoxicol. 1989;11:131-142.
4. Bagnato A, Brovedani P, Comina P, et al. Long-term treatment with thymomodulin reduces airway hyperresponsiveness to methacholine. Ann Allergy. 1989;62:425-428.
5. Civeira MP, Castilla A, Morte S, et al. A pilot study of thymus extract in chronic non-A, non-B hepatitis. Aliment Pharmacol Therap. 1989;3:395-401.
6. Bortolotti F, Cadrobbi P, Crivellaro C, et al. Effect of an orally administered thymic derivative, thymomodulin, in chronic type B hepatitis in children. Curr Ther Res.1988;43:67-72.
7. Galli M, Crocchiolo P, Negri C, et al. Attempt to treat acute type B hepatitis with an orally administered thymic extract (thymomodulin): preliminary results. Drugs Exp Clin Res. 1985;11:665-669.
8. Raymond RS, Fallon MB, Abrams GA. Oral thymic extract for chronic hepatitis C in patients previously treated with interferon. A randomized, double-blind, placebo-controlled trial. Ann Intern Med.1998;129:797-800.
9. Skotnicki AB. Therapeutic application of calf thymus extract (TFX). Med Oncol & Tumor Pharmacother.1989;6:31-43.
10. Leung DY, Hirsch RL, Schneider L, et al. Thymopentin therapy reduces the clinical severity of atopic dermatitis. J Allergy Clin Immunol. 1990;85:927-933.
11. Beall G, Kruger S, Morales F, et al. A double-blind, placebo-controlled trial of thymostimulin in symptomatic HIV-infected patients. AIDS. 1990;4:679-81.
12. Harper JI, Mason UA, White TR, et al. A double-blind placebo-controlled study of thymostimulin (TP-1) for the treatment of atopic eczema. Br J Dermatol. 1991;125:368-372.
13. Roullet E, Cesaro P, Simon-Lavoine N, et al. Nonathymulin treatment of multiple sclerosis: double-blind pilot study. Acta Neurol Scand. 1989;80:5758.
14. Fransen L, Anthoons J, Hoogewijs G, et al. Thymopentin treatment in genital warts of long duration. Cancer Detect Prev.1988;12:503-509.
15. Malaise M, Franchimont P, Hauwaert C, et al. Confirmative study of the effectiveness of thymopentin in active rheumatoid arthritis. Surv Immunol Res. 1985;4(Suppl 1):87-93.
16. Bolla K, Djawari D, Kokoschka EM, et al. Prevention of recurrences in frequently relapsing herpes labialis with thymopentin. A randomized double-blind placebo-controlled multicenter study. Surv Immunol Res. 1985;4(Suppl 1):37-47.
17. Norton S. Raw animal tissues and dietary supplements. N Engl J Med. 2000;343:304-305.
18. Longo F, Lepore L, Agosti E, Panizon F. Evaluation of the effectiveness of thymomodulin in children with recurrent respiratory infections. Pediatr Med Chir 1988;10:603-607.
19. Vettori G, Lazzaro A, Mazzanti P, Cazzola P. Prevention of recurrent respiratory infections in adults. Minerva Med 1987;78:1281-1289.
20. Genova R, Guerra A. A thymus extract (thymomodulin) in the prevention of childhood asthma. Pediatr Med Chir 1983;5:395-402.
21. Marzari R, Mazzanti P, Cazzola P, Pirodda E. Perennial allergic rhinitis: prevention of the acute episodes with Thymomodulin. Minerva Med 1987;78:1675-1681.
22. Fiocchi A, Grasso U, Travaglini P, et al. A double blind clinical trials on the effectiveness of a thymic derivative (Thymomodulin) in the treatment of children with atopic dermatitis. Int J Immunother 1987;3:279-284.
Last reviewed December 2015 by EBSCO CAM Review Board Last Updated: 12/15/2015