Two randomised controlled trials show that purified shilajit modestly raises testosterone in men aged 45 to 55 over 90 days. The heavy metal contamination risk in Indian commercial products is real and documented. The clinical evidence is product-specific: only third-party tested, standardised extracts carry the data.
Shilajit is a blackish-brown, tar-like exudate from Himalayan rock faces, formed over centuries from compressed decomposed plant matter. Its key bioactives include fulvic acid, humic acid, dibenzo-α-pyrones (DBPs), and over 80 trace minerals. Standardised extracts contain at least 50% fulvic acid and 0.3% DBPs.1
In Ayurvedic tradition it is classified as a rasayana, referenced in the Charaka Samhita for fatigue and reproductive health. Clinically, the form matters: raw resin and loose powder have far less standardised fulvic acid and far greater contaminant variability than encapsulated purified extracts.
Pandit et al. (2016) randomised 75 healthy men aged 45 to 55 to PrimaVie shilajit (250 mg twice daily) or placebo for 90 days.1 Total testosterone, free testosterone, and DHEAS all increased significantly vs. placebo. LH and FSH remained stable, ruling out HPG axis disruption.
Biswas et al. (2010) evaluated processed shilajit in 35 oligospermic men, documenting a 23.5% rise in serum testosterone alongside a 61.4% improvement in sperm count and significant reduction in semen malondialdehyde.2 Hepatic and renal parameters were unaffected.
Proposed mechanisms include effects on mitochondrial function and mineral bioavailability, though these pathways have not been conclusively established in humans. Both studies used a single proprietary extract (PrimaVie, Natreon Inc.) and results cannot be generalised to other products.
Fatigue and strength: Study showed Shilajit for 8 weeks retained maximal isometric strength post-fatigue and reduced serum hydroxyproline, a collagen degradation marker.3
Cognition: Fulvic acid inhibits tau protein aggregation in preclinical models. No human RCTs exist yet.
Bone and collagen: Study in 2024 documented a significant rise in pro-C1α1, a type I collagen biomarker, after 8 weeks of supplementation.6 Clinical relevance for osteoporosis remains untested.
Cancer: A 2026 AIIMS Vijaypur systematic review in Cureus synthesised nine preclinical studies, all showing dose-dependent cytotoxicity in vitro.4 The authors corrected their own title post-publication to remove 'evidence-based'. No human trials exist.
Hussain and Saeed (2024) confirmed shilajit contains approximately 65 metallic elements, including toxic Pb, As, Cd, Hg, Al, and Cu.5 Humic substances partially chelate around 12 of these, but the clinical significance of this chelation is uncharacterised.
The 'purified' label is unregulated. According to ConsumerLab's 2024 independent analysis of eight commercial products, fulvic acid content varied by nearly 32,000% across brands, with raw resins providing a fraction of what standardised capsules contain.
A 2025 peer-reviewed study found thallium levels in some processed supplements actually exceeded raw source material concentrations, suggesting certain manufacturing processes concentrate rather than remove this neurotoxic metal.5 Thallium toxicity produces peripheral neuropathy, alopecia, and renal failure.
Shilajit sold as an Ayurvedic medicine falls under AYUSH, bypassing pre-market clinical trials. As a nutraceutical it falls under FSSAI's 2022 Health Supplements Regulations, which include heavy metal limits, but enforcement across India's fragmented supplement market is inconsistent. Schedule T of the Drugs and Cosmetics Act sets minimum GMP standards for AYUSH products.
Before buying, verify all five of the following:
NABL-accredited COA Confirms heavy metals below WHO permissible limits
Fulvic acid on label Minimum 50% for standardised extracts
Batch-level testing Not just general brand certification
Schedule T / GMP Manufacturer compliance confirmed
Himalayan source Most documented origin in clinical trials
Pregnant and breastfeeding women: Absolutely contraindicated. No safety data. Foetal heavy metal exposure risk.
Children and adolescents: No paediatric trials. Proportionally higher accumulation risk due to lower body weight.
Chronic kidney disease: Fulvic acid's chelating action may disrupt tubular mineral handling and elevate accumulation risk. Patients with chronic kidney disease should avoid use unless supervised by a physician because safety data are lacking.
Patients on iron therapy: Shilajit enhances iron absorption. Iron overload risk, particularly in haemochromatosis.
Undiagnosed hormonal conditions: PCOS, hypogonadism, thyroid or adrenal disorders require formal evaluation before any adaptogen.
Antihypertensive, antidiabetic, or anticoagulant users: Interactions proposed but uncharacterised in human trials. Physician consultation required.
Heavy metal toxicity is insidious: symptoms appear weeks to months after exposure and are often misattributed. Discontinue immediately and seek evaluation if any of the following develop after starting shilajit:
Neurological: Peripheral tingling, numbness, tremor, or cognitive slowing
Gastrointestinal: Persistent nausea, vomiting, or cramping temporally linked to supplementation
Renal: Reduced urine output, oedema, or unexplained urinalysis changes
Dermatological: Alopecia, hyperpigmentation, or Mees' lines on nails (arsenic/thallium markers)
Systemic: Fatigue or anaemia without nutritional cause, with temporal link to shilajit use
Workup: FBC, LFT, RFT, and blood Pb/As/Hg/Tl levels where indicated. Testing should be guided by clinical suspicion and exposure history. Chelation only under specialist supervision.
The evidence is real but narrow. Two RCTs using one proprietary extract support modest testosterone improvement in middle-aged men over 90 days. One RCT supports fatigue resistance. Bone and cognitive data are preliminary. No anticancer human data exist.
The contamination risk is equally real. The clinical evidence and the commercial product are not the same thing. For a middle-aged man with low-normal testosterone, no contraindications, and access to a verified standardised extract, a 90-day trial with baseline and post-treatment hormone panel is reasonable. For everyone else, evidence does not justify the safety burden of an under-regulated market.
Sleep, resistance training, zinc, and vitamin D remain better-evidenced, lower-risk, and more affordable strategies for testosterone optimisation.
Shilajit is used in Ayurvedic medicine as a rejuvenator for fatigue and reproductive health. Clinical trials support modest testosterone and energy improvements in middle-aged men with purified extracts. Cognitive and bone applications are under study but not established. It is not approved to treat or cure any condition.
With purified, standardised extracts at studied doses, 90-day daily use was well tolerated in trials, with no hepatic or renal changes. Unpurified or untested products carry cumulative heavy metal accumulation risk. Lead, arsenic, and thallium do not produce immediate symptoms, making verified product quality non-negotiable for daily use.
No, and the clinical distinction matters. Erectile dysfunction is most commonly vascular (endothelial dysfunction, reduced penile blood flow) or neurological (autonomic neuropathy), neither of which is addressed by shilajit. Shilajit's studied mechanisms are metabolic and hormonal: modest testosterone support in men with age-related decline. It has no PDE5 inhibitory action, no vasodilatory effect, and no clinical evidence of improving erectile function by any pathway. Men experiencing erectile dysfunction require medical evaluation, not a supplement substitute.
With purified extracts at studied doses, trials reported minimal side effects, chiefly mild gastrointestinal discomfort in some users. The serious risk is contamination: heavy metal toxicity from unpurified products can cause neuropathy, hair loss, renal impairment, and organ damage. Discontinue and seek evaluation if unexplained neurological symptoms, alopecia, or fatigue develop after starting shilajit.
Human trial data in women are almost entirely absent. Preclinical evidence suggests anti-inflammatory, antioxidant, and bone-supportive properties via fulvic acid, which are physiologically relevant to postmenopausal women. No RCTs have evaluated shilajit in female populations. Shilajit is contraindicated in pregnancy and breastfeeding due to heavy metal exposure risk and a complete absence of safety data.
A note from the author: We spent centuries dismissing Indian traditional medicine systems, Ayurveda, Siddha, Unani, rather than investigating them. Shilajit was not discovered by a clinical trial. It was always known. What modern research is doing is providing the evidence framework this era demands, and that is genuinely valuable. But as we build that evidence, we owe some intellectual honesty about what we chose to study late and why. The science on shilajit is still young. Our knowledge systems were not.
Pandit, S., Biswas, S., Jana, U., De, R. K., Mukhopadhyay, S. C., & Biswas, T. K. (2016). Clinical evaluation of purified Shilajit on testosterone levels in healthy volunteers. Andrologia, 48(5), 570-575. https://doi.org/10.1111/and.12482
Biswas, T. K., Pandit, S., Mondal, S., Biswas, S. K., Jana, U., Ghosh, T., Tripathi, P. C., Debnath, P. K., Auddy, R. G., & Auddy, B. (2010). Clinical evaluation of spermatogenic activity of processed Shilajit in oligospermia. Andrologia, 42(1), 48-56. https://doi.org/10.1111/j.1439-0272.2009.00956.x
Keller, J. L., Housh, T. J., Hill, E. C., Smith, C. M., Schmidt, R. J., & Johnson, G. O. (2019). The effects of Shilajit supplementation on fatigue-induced decreases in muscular strength and serum hydroxyproline levels. Journal of the International Society of Sports Nutrition, 16(1), 3. https://doi.org/10.1186/s12970-019-0270-2
Das, S. S., Ramkumar, M., Singh, H., & Sharma, S. (2026). Pre-clinical evaluation of Shilajit in cancer: A systematic review. Cureus, 18(1), e101736. https://doi.org/10.7759/cureus.101736
Hussain, A., & Saeed, A. (2024). Hazardous or advantageous: Uncovering the roles of heavy metals and humic substances in Shilajit (phyto-mineral) with emphasis on heavy metals toxicity and their detoxification mechanisms. Biological Trace Element Research, 202, 5794-5814. https://doi.org/10.1007/s12011-024-04109-4
Neltner, T. J., Sahoo, P. K., Smith, R. W., Anders, J. P. V., Arnett, J. E., Schmidt, R. J., Johnson, G. O., Natarajan, S. K., & Housh, T. J. (2024). Effects of 8 Weeks of Shilajit Supplementation on Serum Pro-c1α1, a Biomarker of Type 1 Collagen Synthesis: A Randomized Control Trial. Journal of dietary supplements, 21(1), 1–12. https://doi.org/10.1080/19390211.2022.2157522
Iqubal, A., & Qadir, A. (2025). Clinical studies and safety evidence for human consumption of Shilajit: a herbo-mineral compound with multifaceted health benefits. International Journal of Basic & Clinical Pharmacology, 14(4), 630–640. https://doi.org/10.18203/2319-2003.ijbcp20251850
Disclaimer: This article is for educational purposes only. Shilajit is not approved by FSSAI or the US FDA to treat any medical condition. This content does not constitute medical advice. Consult a qualified healthcare provider before starting any supplement, especially if you have a pre-existing condition or take prescription medications.