"Immunity Booster" and "Rejuvenation" Claims Checked
Checks Ayurvedic "immunity booster," rasayana and "reverse aging" claims against NCCIH, trial reviews and liver-injury reports, with plain evidence labels and safety cautions.
Content last updated . This page has not been medically reviewed.
What the words mean
In Ayurveda, a rasayana is a rejuvenating herb or preparation. Ashwagandha is described as a Rasayana or rejuvenator, [1] and a 2020 review calls it one of the most-studied Rasayana botanicals, used in practice for immunomodulatory, anti-aging, adaptogenic and rejuvenating effects. [2] Marketing then turns that into modern phrases such as "immunity booster," "anti-aging" or "reverse aging." These are different claims. The tradition describes a purpose. A trial measures an outcome in people compared with a placebo or another treatment. This page checks the second.Evidence labels: traditional use only, insufficient evidence, promising but limited, mixed, evidence of harm (for specific reports), marketing claim.
Claims checked
| Claim | What was found | Label |
|---|---|---|
| "Ashwagandha boosts immunity" or protects against COVID-19 | NCCIH: not enough high-quality evidence that it helps treat COVID-19 [3] | Insufficient evidence |
| "Chyawanprash protects against infection" | A 2024 meta-analysis of five Indian trials (153,343 people) showed a trend for COVID-19 prevention but with high heterogeneity and bias, so more research was recommended [4] | Insufficient evidence |
| "Giloy (guduchi) is a safe immune booster" | A six-patient case series linked it to autoimmune-like hepatitis; other experts dispute the cause [5][6] | Evidence of harm reports, disputed; benefit traditional use only |
| "Rasayana herbs reverse aging" | Proper evidence not found for reversal; reviews describe proposed mechanisms and call for large, long trials [1] | Marketing claim / preclinical to insufficient evidence |
| "Ayurveda rejuvenates" in general | A 2026 narrative review says evidence is heterogeneous and often from small or preliminary studies [7] | Insufficient evidence |
Immunity
The immune system is complex, and "boosting" it is not clearly a good thing. See How the immune system works and Herbs and mushrooms for immunity.- Chyawanprash. The meta-analysis pooled five randomized trials in India. Odds ratios for COVID-19 infection had very wide confidence intervals that crossed no effect (0.45; 95% CI 0.06 to 3.08), and the authors point to heterogeneity and bias. [4] Read the full check at Chyawanprash and "immunity" claims.
- Ashwagandha. NCCIH says it has been promoted for COVID-19 but there is not enough high-quality evidence. [3] It also advises that ashwagandha is not recommended for people with autoimmune or thyroid disorders and might interact with immune-suppressing medicines. [3]
- Giloy. Tinospora cordifolia was widely used in India as an immune booster during COVID-19. [5] Six patients who took it developed acute hepatitis, and the authors suggested it may unmask autoimmune liver disease, particularly in people predisposed to it. [5] Another review argued the product species was not authenticated and a wrong species could be responsible. [6] The cause is not settled. See Giloy (guduchi) in Ayurveda.
Rejuvenation and aging
A 2025 review of ashwagandha describes it as a Rasayana and discusses proposed anti-aging mechanisms, but itself says large-scale, long-term clinical trials with standardized extracts are essential to confirm any role in healthy aging. [1] NCCIH says there is not enough evidence to decide whether ashwagandha helps conditions beyond insomnia and stress, with limited evidence about testosterone and sperm quality. [3] We found no study showing that any Ayurvedic herb reverses aging in people. For what research measures in aging, see Healthspan and lifespan.What we searched: PubMed for Rasayana and aging reviews and trials (found narrative reviews, not trials showing reversal); and Chyawanprash systematic reviews (found the COVID-19 prophylaxis meta-analysis).
Frequently asked questions
Is there an Ayurvedic immunity booster that works?
We did not find good evidence for one. The Chyawanprash meta-analysis recommended further research because of heterogeneity and bias. [4]
Does ashwagandha help with COVID-19?
NCCIH says there is not enough high-quality evidence that it does. [3]
Can Ayurvedic rasayana reverse aging?
No study we read shows reversal. Reviews call for large, long-term trials. [1]
Is giloy safe?
Reports link it with liver injury in some people, and the cause is debated. Ask a clinician first if you have liver or autoimmune conditions. [5][6]
Should I take an immune supplement during a cold?
Ask a clinician or pharmacist. This site's overview is at Supporting immune health.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety first
- Frequent or severe infections are a reason to see a doctor, not to add a supplement. See Frequent illness and low immunity.
- Liver injury has been reported with ashwagandha and giloy products. [3][5]
- Some Ayurvedic preparations may contain lead, mercury or arsenic. [8]
- Do not use Ayurvedic medicine to postpone seeing a conventional provider. [8]
References
- Vittal M, Vinciguerra M. Enhancing healthspan with Ashwagandha (Withania somnifera): a comprehensive review of its multifaceted geroprotective benefits. Biogerontology 2025 (narrative review). Read 2026-10-22.
- Saggam A et al. Withania somnifera (L.) Dunal: a potential therapeutic adjuvant in cancer. J Ethnopharmacol 2020 (narrative review). Read 2026-10-22.
- NCCIH. Ashwagandha: Usefulness and Safety (last updated March 2023). Read 2026-10-22.
- Sharma S et al. Safety and efficacy of Chyawanprash as a prophylaxis treatment for COVID-19: a systematic review and meta-analysis of randomized control trials. Cureus 2024. Read 2026-10-22.
- Nagral A et al. Herbal immune booster-induced liver injury in the COVID-19 pandemic: a case series. J Clin Exp Hepatol 2021. Read 2026-10-22.
- Panneer Selvam K et al. Can Guduchi (Tinospora cordifolia), a well-known ayurvedic hepato-protectant cause liver damage? J Ayurveda Integr Med 2023. Read 2026-10-22.
- Anirudhan R et al. Ayurveda in contemporary healthcare: a narrative overview of select therapeutic interventions and their emerging clinical and mechanistic perspectives. Cureus 2026. Read 2026-10-22.
- National Center for Complementary and Integrative Health (NCCIH, US). Ayurvedic Medicine: In Depth (last updated January 2019). Read 2026-10-22.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.