Chronic psychological and physiological stress, particularly when compounded by inadequate rest and recovery, can progressively undermine immune competence. Over time, chronic stress and lack of convalescence may deplete immune resilience and reduce the body’s capacity to defend against infection.

How does chronic stress deplete the immune system?

Chronic stress drives prolonged activation of the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic nervous system (SNS), resulting in sustained elevations in cortisol and catecholamines. While short-term stress responses can be beneficial, chronic stress contributes to immune dysregulation and suppression. Over time, this weakens certain aspects of the immune response and increases susceptibility to infection.^1,2

Which herbs help to boost immune resilience and support convalescence?

Withania somnifera (Withania), Echinacea purpurea (Echinacea), Astragalus membranaceus (Astragalus), Lentinula edodes (Shiitake), and Ganoderma lucidum (Reishi) provide complementary support for bolstering immune resilience and aiding recovery. Together, these herbs and medicinal mushrooms exert adaptogenic, tonic and immune modulating actions, helping to buffer the impact of chronic stress on immune function while strengthening host defence. This makes them particularly valuable during chronic infections, prolonged fatigue states and extended recovery periods, including post-viral syndromes.³

When is the best time to start taking these herbs?

For preventative use:
Astragalus, Shiitake, Reishi, and Withania, can be taken during periods of ongoing stress, high workload and poor sleep. Building immune resilience is most effective when begun before infection or burnout occurs. These herbs can and should be taken to boost immunity before and during cold and flu season.

At first signs of infection:
Echinacea is most effective when started at the earliest sign of infection⁴ (e.g. scratchy or sore throat, mild nasal congestion or ‘stuffiness’, unusual tiredness, general malaise, or otherwise feeling like you’re ‘coming down with something’). However, herbs with immune stimulating actions (e.g. Andrographis) and classic cold and flu supplements (e.g. vitamin C and zinc) are typically more appropriate to pair with Echinacea when fighting an infection, rather than tonic herbs.

How long should these herbs be taken for?

Adaptogenic and tonic herbs (Withania, Astragalus, Shiitake, and Reishi) are often given for 4 to 12 weeks for stress or recovery support,^5-12 and sometimes longer under practitioner supervision. They are generally suitable for sustained use.

Echinacea is commonly used short term for acute infections, but it may also be used preventatively for months at a time, especially during stressful periods or prophylactically for upper respiratory symptom prevention.^13-16 Evidence supports the use of Echinacea for recurrent infections in children, including alongside antibiotics.¹⁷

Duration of use should reflect the clinical picture, including acute or recurrent illness, chronic stress and slow recovery.

Are these herbs safe for all ages? When should you be cautious about prescribing these herbs?

These herbs are generally well tolerated, but suitability varies in the certain cases:

• Children: lower, weight-adjusted doses are required, but there are no known cautions associated with using these herbs in children. Echinacea in particular is widely and safely used in children.^13,18-21 Withania is traditionally used in Ayurveda as a children’s tonic and has been safely used in clinical trials (age ≥3 years).^22-24
• Pregnancy and breastfeeding: it is safest to avoid using Withania in pregnancy,^25,26 though it can be used during lactation.²⁷ There are no known cautions regarding the use of Echinacea, Astragalus, Reishi, and Shiitake.
• Autoimmune diseases, immunosuppression therapy or organ transplantation: while potentially beneficial for patients with autoimmune diseases, these herbs do modulate immune function and should be used cautiously and under supervision. Assess risks and benefits, particularly for transplant recipients. If using, patients could be started on low doses while monitoring for changes.
• Acute infections: traditional evidence suggests Astragalus should be avoided in acute infections.²⁶ Use with caution; consider the risk to benefit.
• Allergies: individuals who are allergic or hypersensitive to Shiitake²⁸ and Solanaceae/nightshade family plants (including Withania)¹⁰ should not use these herbs. Those with Asteraceae/Echinacea allergies or hypersensitivities should use Echinacea root with caution, and entirely avoid Echinacea products containing flowering tops/aerial parts.²⁹ Echinacea-naïve patients, particularly atopic individuals, should use Echinacea cautiously.³⁰
• Gastrointestinal disorders: Withania may cause digestive discomfort in some people and at high doses.^26,31,32 Use with caution.
• Thyroid conditions: Withania is best avoided in patients with hyperthyroidism.^33-37

As with introducing any new treatment, individual assessment is important. The above information does not include an evaluation of potential herb-drug interactions. *For further guidance, including herb-drug interactions, please contact Clinical Support at clinicalsupport@integria.com.

What else can you do to strengthen your immunity?

Building immune resilience is a sustained effort. Even the best herbal formulation may fall short if not complemented by diet and lifestyle habits that support immunity and reduce the burden of chronic stress long term. Pair strongly indicated herbs with foundational lifestyle strategies centred around good nutrition and adequate hydration, key vitamins and minerals, sunlight and vitamin D optimisation, stress management, restorative sleep, and regular exercise. *For more information refer to the Eagle Tips for Supporting Optimal Immune Functions patient handout, available from practitioner.integria.com/articles/tips-for-supporting-optimal-immune-functions.

References

1. Alotiby A. Immunology of stress: a review article. J Clin Med. 2024 Oct;13(21):6394. DOI: 10.3390/jcm13216394

2. Chu B, Marwaha K, Sanvictores T, Awosika AO, Ayers D. Physiology, stress reaction [Internet]. Treasure Island: StatPearls; 2024 [cited 2026 Feb 19]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK541120/

3. Bone K. The ultimate herbal compendium: a desktop guide for herbal prescribers. Warwick: Phytotherapy Press; 2007.

4. Aucoin M, Cooley K, Saunders PR, Carè J, Anheyer D, Medina DN, et al. The effect of Echinacea spp. on the prevention or treatment of COVID-19 and other respiratory tract infections in humans: a rapid review. Adv Integr Med. 2020 Dec;7(4):203-217. DOI: 10.1016/j.aimed.2020.07.004

5. Chen SN, Nan FH, Liu MW, Yang MF, Chang YC, Chen S. Evaluation of immune modulation by β-1,3; 1,6 D-glucan derived from Ganoderma lucidum in healthy adult volunteers, a randomized controlled trial. Foods. 2023 Feb;12(3):659. DOI: 10.3390/foods12030659

6. Latour E, Arlet J, Latour EE, Juszkiewicz A, Łuczkowska K, Marcinkiewicz A, et al. Standardized astragalus extract for attenuation of the immunosuppression induced by strenuous physical exercise: randomized controlled trial. J Int Soc Sports Nutr. 2021 Jul;18(1):57. DOI: 10.1186/s12970-021-00425-5

7. Salve J, Pate S, Debnath K, Langade D. Adaptogenic and anxiolytic effects of ashwagandha root extract in healthy adults: a double-blind, randomized, placebo-controlled clinical study. Cureus. 2019 Dec;11(12):e6466. DOI: 10.7759/cureus.6466

8. Choudhary D, Bhattacharyya S, Joshi K. Body weight management in adults under chronic stress through treatment with ashwagandha root extract: a double-blind, randomized, placebo-controlled trial. J Evid Based Complementary Altern Med. 2017 Jan;22(1):96-106. DOI: 10.1177/2156587216641830

9. Dai X, Stanilka JM, Rowe CA, Esteves EA, Nieves C, Spaiser SJ, et al. Consuming Lentinula edodes (shiitake) mushrooms daily improves human immunity: a randomized dietary intervention in healthy young adults. J Am Coll Nutr. 2015;34(6):478-487. DOI: 10.1080/07315724.2014.950391

10. Chandrasekhar K, Kapoor J, Anishetty S. A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root in reducing stress and anxiety in adults. Indian J Psychol Med. 2012 Jul;34(3):255-262. DOI: 10.4103/0253-7176.106022

11. Weng XS. [Treatment of leucopenia with pure Astragalus preparation-- an analysis of 115 leucopenic cases]. Zhongguo Zhong Xi Yi Jie He Za Zhi. 1995 Aug;15(8):462-464.

12. Hou YD, Ma GL, Wu SH, Li YY, Li HT. Effect of radix astragali seu hedysari on the interferon system. Chin Med J (Engl). 1981 Jan;94(1):35-40.

13. Ogal M, Johnston SL, Klein P, Schoop R. Echinacea reduces antibiotic usage in children through respiratory tract infection prevention: a randomized, blinded, controlled clinical trial. Eur J Med Res. 2021 Apr;26(1):33. DOI: 10.1186/s40001-021-00499-6

14. Schapowal A, Klein P, Johnston SL. Echinacea reduces the risk of recurrent respiratory tract infections and complications: a meta-analysis of randomized controlled trials. Adv Ther. 2015 Mar;32(3):187-200. DOI: 10.1007/s12325-015-0194-4

15. Tiralongo E, Lea RA, Wee SS, Hanna MM, Griffiths LR. Randomised, double blind, placebo-controlled trial of echinacea supplementation in air travellers. Evid Based Complement Alternat Med. 2012;2012:417267. DOI: 10.1155/2012/417267

16. Ritchie MR, Gertsch J, Klein P, Schoop R. Effects of Echinaforce® treatment on ex vivo-stimulated blood cells. Phytomedicine. 2011 Jul;18(10):826-831. DOI: 10.1016/j.phymed.2011.05.011

17. Abdel-Naby Awad OG. Echinacea can help with azithromycin in prevention of recurrent tonsillitis in children. Am J Otolaryngol. 2020 Jul-Aug;41(4):102344. DOI: 10.1016/j.amjoto.2019.102344

18. Minetti AM, Forti S, Tassone G, Torretta S, Pignataro L. Efficacy of complex herbal compound of Echinacea angustifolia (Imoviral® Junior) in recurrent upper respiratory tract infections during pediatric age: preliminary results. Minerva Pediatr. 2011 Jun;63(3):177-182.

19. Saunders PR, Smith F, Schusky RW. Echinacea purpurea L. in children: safety, tolerability, compliance, and clinical effectiveness in upper respiratory tract infections. Can J Physiol Pharmacol. 2007 Nov;85(11):1195-1199. DOI: 10.1139/Y07-103

20. Cohen HA, Varsano I, Kahan E, Sarrell EM, Uziel Y. Effectiveness of an herbal preparation containing echinacea, propolis, and vitamin C in preventing respiratory tract infections in children: a randomized, double-blind, placebo-controlled, multicenter study. Arch Pediatr Adolesc Med. 2004 Mar;158(3):217-221. DOI: 10.1001/archpedi.158.3.217

21. Parnham MJ. Benefit-risk assessment of the squeezed sap of the purple coneflower (Echinacea purpurea) for long-term oral immunostimulation. Phytomed. 1996;3(1):95-102. DOI: 10.1016/S0944-7113(96)80020-1

22. Singh N, Bhalla M, De Jager P, Marilena Gilca M. An overview on ashwagandha: a rasayana (rejuvenator) of Ayurveda. Afr J Tradit Complement Altern Med. 2011;8(5 Suppl):208-213. DOI: 10.4314/ajtcam.v8i5S.9

23. Katz M, Adar Levine A, Kol-Degani H, Kav-Venaki L. A compound herbal preparation (CHP) in the treatment of ADHD: a randomized controlled clinical trial. J Atten Disord. 2010;13(3):281-291. DOI: 10.1177/1087054709356388

24. Mishra RK, Trivedi R, Pandya MA. A clinical study of ashwagandha ghrita and ashwagandha granules for its brumhana and balya effect. Ayu. 2010 Jul-Sep;31(3):355-360. DOI: 10.4103/0974-8520.77164

25. Paul S, Chakraborty S, Anand U, Dey S, Nandy S, Ghorai M, et al. Withania somnifera (L.) Dunal (ashwagandha): a comprehensive review on ethnopharmacology, pharmacotherapeutics, biomedicinal and toxicological aspects. Biomed Pharmacother. 2021 Nov;143:112175. DOI: 10.1016/j.biopha.2021.112175

26. Bone K, Mills S. Principles and practice of phytotherapy: modern herbal medicine. 2nd ed. London: Churchill Livingstone; 2013.

27. Foong SC, Tan ML, Foong WC, Marasco LA, Ho JJ, Ong JH. Oral galactagogues (natural therapies or drugs) for increasing breast milk production in mothers of non-hospitalised term infants (review). Cochrane Database Syst Rev. 2020;5:CD011505. DOI: 10.1002/14651858.CD011505.pub2

28. Gardner Z, McGuffin M. American Herbal Products Association’s botanical safety handbook. 2nd ed. Boca Raton: CRC Press; 2013.

29. Denisow-Pietrzyk M, Pietrzyk Ł, Denisow B. Asteraceae species as potential environmental factors of allergy. Environ Sci Pollut Res Int. 2019;26(7):6290-6300.

30. Mullins RJ, Heddle R. Adverse reactions associated with echinacea: the Australian experience. Ann Allergy Asthma Immunol. 2002;88(1):42-51. DOI: 10.1016/S1081-1206(10)63591-0

31. Majeed M, Nagabhushanam K, Murali A, Vishwanathan DT, Mamidala RV, Mundkur L. A standardized Withania somniferra (Linn.) root extract with piperine alleviates the symptoms of anxiety and depression by increasing serotonin levels: a double-blind, randomized, placebo-controlled study. J Integr Complement Med. 2023 Oct. DOI: 10.1089/jicm.2023.0279

32. Tandon N, Yadav SS. Safety and clinical effectiveness of Withania somnifera (Linn.) Dunal root in human ailments. J Ethnopharmacol. 2020 Jun:255:112768. DOI: 10.1016/j.jep.2020.112768

33. Hayashi M, Hamada H, Azuma S-I, Hayashi K. Painless thyroiditis by Withania somnifera (ashwagandha). Cureus. 2024;16(3):e55352. DOI: 10.7759/cureus.55352

34. Kamal HI, Patel K, Brdak A, Heffernan J, Ahmad N. Ashwagandha as a unique cause of thyrotoxicosis presenting with supraventricular tachycardia. Cureus. 2022 Mar;14(3):e23494. DOI: 10.7759/cureus.23494

35. Curry KM, McNeil LE, Flores A, Fuks J. Thyrotoxicosis with ashwagandha: a case report. Soc Sci Res Net. 2019 Dec. DOI: 10.2139/ssrn.3506409

36. Sharma AK, Basu I, Singh S. Efficacy and safety of ashwagandha root extract in subclinical hypothyroid patients: a double-blind, randomized placebo-controlled trial. J Altern Complement Med. 2018 Mar;24(3):243-248. DOI: 10.1089/acm.2017.0183

37. Van Der Hooft CS, Hoekstra A, Winter A, De Smet PAG, Ch Stricker BH. [Thyrotoxicosis following the use of ashwagandha]. Ned Tijdschr Geneeskd. 2005 Nov;149(47):2637-2638.