Titus Thorne

Last Updated November 6, 2022

Titus Thorne

 November 6, 2022

Curious about thymosin alpha-1 side effects?

Then you’ve come to the perfect place. Inside, we break down what researchers must know about this ultimate immunity booster.

Generally speaking, the side effects related to thymosin alpha-1 appear to be rare and relatively mild in nature. The available research indicates that thymosin alpha-1 is well tolerated, while most studies have reported only injection-related side effects, such as irritation at the injection site.

In this guide, we provide researchers with what they should know about thymosin alpha-1 side effects, as well as information on the peptide’s benefits and how it may be dosed.

In case you’re looking to get started with thymosin alpha-1 right away, skip down to get information on our recommended vendor of Tα1 and other research peptides.

Buy Thymosin Alpha-1 from our #1 recommended vendor...

Disclaimer: Peptides.org contains information about products that are intended for laboratory and research use only, unless otherwise explicitly stated. This information, including any referenced scientific or clinical research, is made available for educational purposes only. Peptides.org makes every effort to ensure that any information it shares complies with national and international standards for clinical trial information and is committed to the timely disclosure of the design and results of all interventional clinical studies for innovative treatments publicly available or that may be made available. However, research is not considered conclusive. Peptides.org makes no claims that any products referenced can cure, treat or prevent any conditions, including any conditions referenced on its website or in print materials.

What is Thymosin Alpha-1?

Thymosin alpha-1 (Tα1) is a small protein (peptide) that consists of 28 amino acids and is produced naturally by the thymus gland. The peptide is a potent immune system modulator that has been used for decades to treat immunocompromised subjects and enhance subjects’ vaccine response, among other uses [1, 2, 3].

The thymus, where Tα1 is produced, is a small gland in the lymphatic system that has the role of making T cells, which assist the immune system in recalling past infections by targeting specific particles. Tα1 works to increase the activity of T cell maturation into CD4+/CD8+ T cells, thus activating the body’s immune response [3].

The peptide’s mechanism of action is pleiotropic, as it affects multiple immune cell subsets that are involved in immune suppression, whether associated with aging or diseases like cancer. Researchers have found that it works through toll-like receptors in both myeloid and plasmacytoid cells, ultimately stimulating signaling pathways within the immune system as well as the production of immune-related cytokines [4].

These mechanisms allow thymosin alpha-1 to stimulate an immune response that is essential for fighting viral, bacterial, and fungal infections and cancers. To that end, the peptide has been used therapeutically in patients with evident immune dysfunction, and has been reviewed in a variety of clinical trials including for non-small cell lung cancer, hepatocellular carcinoma, hepatitis B and C, HIV, and melanoma [3, 4].

Thymosin Alpha Side Effects

Thymosin Alpha-1 Side Effects

The side effects related to thymosin alpha-1 appear to be rare and relatively minimal, one of the principal benefits of the peptide.

The safety of thymosin alpha-1 has been demonstrated in clinical trials. For example, the peptide has been evaluated to treat hepatitis B in 195 patients across four clinical trials, and for hepatitis C in 162 patients across three clinical trials. Following these studies, the researchers have noted that thymosin alpha-1 is well tolerated, with injection site irritation as generally the only side effect observed [1].

In addition, a 2016 survey of data on adverse drug reactions and interactions stated that thymosin alpha-1 has a very favorable adverse reactions profile in over two thousand subjects treated [5].

Researchers have, however, observed the following minor side effects in relation to thymosin alpha-1 [1, 3, 7]:

  • redness/discomfort at injection site;
  • muscle and joint pains;
  • fever;
  • fatigue; and
  • swelling and rash of the hand.

In clinical trials, thymalfasin (the synthetic form of thymosin alpha-1) has additionally been reported to produce side effects like nausea, vomiting, and neutropenia, when combined with interferon 2b, an antiviral drug often prescribed as part of treatment regimens for hepatitis, cancer, and genital warts [3].

The lack of significant side effects reported with thymosin alpha-1 is in sharp contrast to other major immune response modulators like IFN and IL-2, associated with flu-like symptoms including malaise, fever, headache, and chills. Adverse effects in relation to IFN have been described in almost every organ system, with patients often experiencing severe toxicities [6].

Thymosin Alpha-1 Benefits

Research conducted in relation to thymosin alpha-1 has found that the peptide offers numerous benefits. Here is a non-exhaustive list:

Anticancer activity. Researchers tested thymosin alpha-1 on human lung cancer cells (A549), finding that the peptide had anti-proliferative-effects and reduced both the growth and metastasis of cancerous cells. To date, the peptide has yielded positive outcomes in cases of breast cancer, melanoma, liver cancer, lung cancer, and colon cancer—to name a few [8].

ACE inhibitor. Researchers have determined that thymosin alpha-1 blocks angiotensin converting enzyme (ACE), with the corresponding effect of reducing blood pressure. Tα1 is believed to be a safer alternative to many ACE inhibiting drugs on the market, which have side effects like drowsiness and weakness [9].

Inflammation reduction. Based on research into the peptide’s ability to modulate dendritic cell (DC) function, thymosin alpha-1 is a known endogenous regulator with the ability to control inflammation in a variety of clinical settings [10].

Antifungal activity. Due also to its ability to activate dendritic cells, thymosin alpha-1 has been shown to produce antifungal immune resistance in the lungs of mice afflicted with Aspergillus fumigatus, among the most important airborne fungal pathogens affecting humans [11].

Immune function. Research has indicated thymosin alpha-1 plays the role of a regulator of immunity, tolerance, and inflammation, and that low levels of serum thymosin alpha-1 are associated with reduced immune function and susceptibility to disease [12].

Cognition booster. Research conducted on mice indicates thymosin alpha-1 is a key potentiator of neurodevelopment and that peripheral administration of the peptide can actually boost cognitive function [13].

Thymosin Alpha-1 Dosage

In research settings, thymosin alpha-1 is typically administered via subcutaneous injection.

To properly administer thymosin alpha-1, researchers should have the right items on hand, including their thymosin alpha-1 vial, a vial of bacteriostatic water, sterile syringes, and alcohol wipes. Here is a brief guide to administering a thymosin alpha-1 injection:

  • Reconstitute the thymosin alpha-1 using bacteriostatic water.
  • Hold the vial of reconstituted solution upright and insert your injection syringe in the center.
  • Draw the plunger until you have the correct amount of peptide, before carefully removing the syringe.
  • Use an alcohol wipe to cleanse the area of the subject’s skin to which the peptide will be administered.
  • Hold the syringe at a 90 degree angle to the subject’s skin and swiftly insert the syringe, depress the plunger fully, and carefully draw out.

For reference purposes, here is a reference thymosin alpha-1 dosage protocol that may be administered for optimizing immune function in test subjects:

  • Daily Dosage: 500mcg of thymosin-alpha 1.
  • Study Duration: Administer thymosin alpha-1 for 20 days, rotating injection sites.
  • Thymosin Alpha-1 Cycle: Excluding subjects with autoimmune conditions, thymosin alpha-1 is typically not administered year-round, and instead administered for 20-60 days at a time.
  • Notes: Administer thymosin alpha-1 via subcutaneous injection. One 10mg vial of thymosin alpha-1 represents a 20-day course following the above protocol.

Thymosin Alpha Side Effects

Where to Buy Thymosin Alpha-1 Online?

If you are looking to conduct research on thymosin alpha-1, we recommend Peptide Sciences, the web’s most reputable provider of research peptides.

There are several reasons why we trust Peptide Sciences over other online sellers:

  • Science-based approach: The vendor’s website includes detailed research summaries for each peptide listed for sale, including thymosin alpha-1. The vendor is transparent about its production practices and is deeply committed to the research community.
  • Product purity: This vendor sources only from manufacturers that follow the World Health Organization (WHO)/Good Manufacturing Practices (GMP) and ISO 9001:2008 protocols. All Peptide Sciences formulations are manufactured in the USA, in accordance with the highest standards of purity and quality.
  • Attractive prices: Peptide Sciences frequently runs very attractive deals and promotions on research peptides. The vendor is currently waiving shipping fees on US orders over $200, and bulk purchase discounts are available on most peptides.
  • Quality Control: Peptide Sciences undertakes mass spectrometry (MS) and high performance liquid chromatography testing as part of their strict quality control process. This ensures that their peptides meet a 99% purity standard.
  • Customer care: Peptide Sciences is dedicated to all of its customers, with a customer support team that responds promptly and professionally to all inquiries.

This vendor is currently offering thymosin alpha-1 10mg for $130 and thymosin alpha-1 3mg for $45. 

Buy Thymosin Alpha-1 from our #1 recommended vendor...

Bacteriostatic Water for Injection

Every qualified researcher knows that having the correct toolkit is essential for proper experimentation. Particularly when studying peptides such as Thymosin Alpha-1, a researcher requires certain supplies for successful preparation, injection, and storage.

Essential items like bacteriostatic water, needles, and sterile vials should be on hand.

Yet gathering all of these materials can be a drag, detracting time and energy from your research.

Luckily, you don’t have to spend long hours searching for the full range of products from numerous sources! The expert team at Peptides.org has investigated for you to select one top retailer that is guaranteed to meet your research supply requirements.


An order from this leading site delivers the full set of necessary research materials. The efficient and convenient packages from BacteriostaticWater.org are available in two research kit options, each fully equipped with the essentials.

Take your pick of the starter research kit, which offers:

  • Bacteriostatic Water (30mL) – 3x
  • Insulin Syringes (0.5 cc/mL x 29g x ½) – 100x
  • Alcohol Prep Pads – 200x
  • Sterile Empty Glass Vial (10mL) – 1x
  • Large Needles + Syringes Combo (3cc x 21g x 1) – 10x

Select the premium research kit to receive these necessities:

  • Bacteriostatic Water (30mL) – 5x
  • Insulin Syringes (0.5 cc/mL x 29g x ½) – 200x
  • Alcohol Prep Pads – 200x
  • Sterile Empty Glass Vial (10mL) – 2x
  • Large Needles + Syringes Combo (3cc x 21g x 1) – 20x

Give your research a jumpstart with one of these expertly assembled supply kits from our go-to vendor.

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Side Effects of Thymosin Alpha-1 | Verdict

The research conducted to date indicates that thymosin alpha-1 has minimal side effects and is well tolerated.

Thymosin alpha-1 side effects are particularly rare when compared to other major immune response modulators, like interferons and interleukins.

In addition to its limited side effects, research conducted in relation to thymosin alpha-1 has found that the peptide offers numerous benefits stemming from its modulation of dendritic cell function, including anticancer activity, inflammation reduction, and antifungal effects.

Researchers considering further study of thymosin alpha-1 should visit Peptide Sciences for all their peptide needs.


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  2. Schmidt M, Toplak A, Rozeboom HJ, Wijma HJ, Quaedflieg PJLM, van Maarseveen JH, Janssen DB, Nuijens T. Design of a substrate-tailored peptiligase variant for the efficient synthesis of thymosin-α1. Org Biomol Chem. 2018 Jan 24;16(4):609-618. doi: 10.1039/c7ob02812a. PMID: 29300408. (https://pubs.rsc.org/en/content/articlelanding/2018/ob/c7ob02812a)
  3. Dominari A, Hathaway Iii D, Pandav K, Matos W, Biswas S, Reddy G, Thevuthasan S, Khan MA, Mathew A, Makkar SS, Zaidi M, Fahem MMM, Beas R, Castaneda V, Paul T, Halpern J, Baralt D. Thymosin alpha 1: A comprehensive review of the literature. World J Virol. 2020 Dec 15;9(5):67-78. doi: 10.5501/wjv.v9.i5.67. PMID: 33362999; PMCID: PMC7747025. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7747025/)
  4. King R, Tuthill C. Immune Modulation with Thymosin Alpha 1 Treatment. Vitam Horm. 2016;102:151-78. doi: 10.1016/bs.vh.2016.04.003. Epub 2016 May 24. PMID: 27450734 (https://pubmed.ncbi.nlm.nih.gov/27450734/)
  5. Thymosin alpha1. Thymosin Alpha1 – an overview | ScienceDirect Topics. (n.d.). Retrieved August 2, 2022, (https://www.sciencedirect.com/topics/immunology-and-microbiology/thymosin-alpha1)
  6. Sleijfer S, Bannink M, Van Gool AR, Kruit WH, Stoter G. Side effects of interferon-alpha therapy. Pharm World Sci. 2005 Dec;27(6):423-31. doi: 10.1007/s11096-005-1319-7. PMID: 16341948. https://pubmed.ncbi.nlm.nih.gov/16341948/
  7. RxList. (2021, June 28). Side effects of zadaxin (Thymalfasin), warnings, uses. RxList. Retrieved July 26, 2022, (https://www.rxlist.com/zadaxin-side-effects-drug-center.htm)
  8. Kharazmi-Khorassani J, Asoodeh A. Thymosin alpha-1; a natural peptide inhibits cellular proliferation, cell migration, the level of reactive oxygen species and promotes the activity of antioxidant enzymes in human lung epithelial adenocarcinoma cell line (A549). Environ Toxicol. 2019 Aug;34(8):941-949. doi: 10.1002/tox.22765. Epub 2019 May 8. PMID: 31067016. (https://onlinelibrary.wiley.com/doi/abs/10.1002/tox.22765)
  9. Kharazmi-Khorassani J, Asoodeh A, Tanzadehpanah H. Antioxidant and angiotensin-converting enzyme (ACE) inhibitory activity of thymosin alpha-1 (Thα1) peptide. Bioorg Chem. 2019 Jun;87:743-752. doi: 10.1016/j.bioorg.2019.04.003. Epub 2019 Apr 4. PMID: 30974297. (https://pubmed.ncbi.nlm.nih.gov/30974297/)
  10. Romani L, Bistoni F, Montagnoli C, Gaziano R, Bozza S, Bonifazi P, Zelante T, Moretti S, Rasi G, Garaci E, Puccetti P. Thymosin alpha1: an endogenous regulator of inflammation, immunity, and tolerance. Ann N Y Acad Sci. 2007 Sep;1112:326-38. doi: 10.1196/annals.1415.002. Epub 2007 May 10. PMID: 17495242. (https://pubmed.ncbi.nlm.nih.gov/17495242/)
  11. Romani L, Bistoni F, Gaziano R, Bozza S, Montagnoli C, Perruccio K, Pitzurra L, Bellocchio S, Velardi A, Rasi G, Di Francesco P, Garaci E. Thymosin alpha 1 activates dendritic cells for antifungal Th1 resistance through toll-like receptor signaling. Blood. 2004 Jun 1;103(11):4232-9. doi: 10.1182/blood-2003-11-4036. Epub 2004 Feb 24. PMID: 14982877 (https://pubmed.ncbi.nlm.nih.gov/14982877/)
  12. Pica F, Gaziano R, Casalinuovo IA, Moroni G, Buè C, Limongi D, D'Agostini C, Tomino C, Perricone R, Palamara AT, Sinibaldi Vallebona P, Garaci E. Serum thymosin alpha 1 levels in normal and pathological conditions. Expert Opin Biol Ther. 2018 Jul;18(sup1):13-21. doi: 10.1080/14712598.2018.1474197. PMID: 30063864. (https://pubmed.ncbi.nlm.nih.gov/30063864/)
  13. Wang G, He F, Xu Y, Zhang Y, Wang X, Zhou C, Huang Y, Zou J. Immunopotentiator Thymosin Alpha-1 Promotes Neurogenesis and Cognition in the Developing Mouse via a Systemic Th1 Bias. Neurosci Bull. 2017 Dec;33(6):675-684. doi: 10.1007/s12264-017-0162-x. Epub 2017 Aug 5. PMID: 28780644; PMCID: PMC5725380. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5725380/)

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