Abstract
Shilajit, a phyto-mineral resin traditionally used in Ayurvedic medicine, has recently gained commercial prominence as an ingredient in dietary supplements and energy drinks. Despite its historical use, the incorporation of Shilajit into products intended for regular consumption raises substantial public health concerns. This review critically examines the scientific evidence regarding Shilajit's safety profile, with particular emphasis on documented heavy metal contamination, adverse clinical events, the efficacy evidence gap, and the fragmented international regulatory landscape. Analytical studies have detected thallium concentrations up to 0.5 µg/g in commercial supplements—exceeding levels found in crude Shilajit—while other toxic metals including lead, arsenic, cadmium, and mercury have been consistently identified (Kamgar et al., 2025). Regulatory actions from the U.S. Food and Drug Administration, Philippine FDA, and Health Canada underscore persistent safety concerns regarding unapproved therapeutic claims, manufacturing violations, and unregistered products. The paucity of robust clinical evidence supporting purported energy-enhancing effects, combined with documented cases of adverse reactions including anaphylaxis, necessitates stringent quality control, standardized testing protocols, and regulatory harmonization. This review concludes that regular consumption of Shilajit-containing energy drinks cannot be recommended based on current evidence. Recommendations are provided for regulatory authorities to develop evidence-based frameworks ensuring consumer safety.
Keywords: Shilajit, thallium, heavy metals, dietary supplements, energy drinks, anaphylaxis
1. Introduction
Shilajit is a blackish-brown, tar-like exudate that seeps from sedimentary rocks in mountainous regions worldwide, including the Himalayas, Iran, Nepal, Russia, and Kyrgyzstan. Formed through the long-term decomposition of plant and organic matter under specific temperature and pressure conditions, this phyto-mineral substance has been used for centuries in Ayurvedic and Siddha systems of medicine as a rasayana or rejuvenator (Wilson et al., 2011). Its chemical composition is complex and geographically variable, containing humic substances (fulvic acid and humic acid comprising 60–80% of the material), minerals including potassium, calcium, and magnesium, and a range of bioactive phenolic compounds including dibenzo-α-pyrones (Stohs, 2014; Wilson et al., 2011).
In recent years, Shilajit has been marketed as an energy-boosting ingredient, appearing in dietary supplements, capsules, and notably, energy drinks. Commercial claims position it as a natural enhancer of vitality, stamina, endurance, and cognitive performance. However, the scientific basis for these claims remains tenuous, and the safety profile of Shilajit—particularly when consumed regularly as part of an energy drink formulation—has not been adequately established. This review critically evaluates the health risks associated with Shilajit consumption, focusing on heavy metal contamination, documented adverse effects, the efficacy evidence gap, and the regulatory landscape.
2. Heavy Metal Contamination: The Principal Health Hazard
2.1 Thallium Contamination
The most significant and scientifically documented health risk associated with Shilajit is thallium contamination. A pivotal 2025 study published in BMC Chemistry provided a comprehensive quantitative assessment of thallium in 13 crude Shilajit samples and 5 commercial supplements using flow-injection differential-pulse anodic stripping voltammetry. The limit of detection and limit of quantification were determined as 6.58 × 10⁻³ µg/mL and 1.98 × 10⁻² µg/mL, respectively. The findings revealed that thallium concentrations in crude Shilajit ranged from near zero to 0.226 µg/g. Alarmingly, commercial supplement concentrations reached up to 0.5 µg/g, which is higher than levels found in the raw material, suggesting that processing may concentrate the contaminant. Consumption of a single supplement pill introduces up to 0.095 µg of thallium to the body (Kamgar et al., 2025).
The toxicological significance of these findings is profound. Thallium is classified as a priority pollutant due to its mutagenic, carcinogenic, and teratogenic properties. Its toxicity surpasses that of mercury, cadmium, and lead, stemming from its structural similarity to potassium ions, which disrupts potassium-dependent metabolic processes. The LD₅₀ of thallium for humans ranges from 8 to 12 mg/kg, and acute high-dose ingestion can result in fatal outcomes. Prolonged exposure has been associated with liver damage, testicular tissue damage, kidney dysfunction, hair loss, and intestinal damage. The main source of human thallium intake is food, with average intake estimated at less than 2 µg per day. The absence of specific guidelines for daily thallium intake or duration of Shilajit consumption is particularly concerning, as thallium accumulates in various organs over time (Kamgar et al., 2025). Notably, the significant variation in thallium content among samples from different countries and regions can be attributed to the diverse geology and soil composition from which Shilajit is derived (Kamgar et al., 2025).
2.2 Other Toxic Heavy Metals
Shilajit's natural formation process inevitably incorporates metals from surrounding geological strata. Wilson et al. (2011) reported that Shilajit contains significant amounts of heavy metals such as arsenic, lead, mercury, nickel, and cobalt. The presence of these heavy metals, regardless of amount, is particularly concerning, as bioaccumulation can have harmful health effects including cancer and damage to organs such as the kidneys, brain, heart, skin, and liver (Stohs, 2014; Wilson et al., 2011). A comprehensive review noted that Shilajit contains numerous heavy metals, and the recommended levels of heavy metals by the World Health Organization and FDA in herbal drugs are 0.20 and 0.30 ppm for cadmium, 1 ppm for mercury, and 10.00 ppm for arsenic and lead (Stohs, 2014). Without rigorous laboratory testing, there is no way to verify the actual composition of a Shilajit product or whether it is free of heavy metals.
3. Documented Adverse Effects
3.1 Clinical Adverse Events: Anaphylaxis
Beyond heavy metal toxicity, Shilajit consumption has been associated with severe adverse effects documented in clinical case reports. A critical case report published in the European Annals of Allergy and Clinical Immunology describes a 43-year-old woman who experienced a life-threatening allergic reaction after taking Shilajit at a dose of 400 mg/day. The patient developed urticaria after ingestion of rice, tuna, and Shilajit, which did not respond to intramuscular corticosteroids. Subsequently, she developed dyspnoea and hypotension with loss of consciousness that arose one hour after sexual activity. The patient had no personal history of atopy, and specific IgE for main food allergens was negative. Serum tryptase at the time of anaphylaxis was 20.6 μg/L, which fell to 10.6 μg/L after therapy but remained elevated during follow-up. The diagnosis was consistent with exercise-induced anaphylaxis in a patient with possible mast cell activation syndrome. The authors concluded that although Shilajit has shown a high degree of safety in some contexts, it can act as a cofactor of anaphylaxis, especially in patients with risk factors (Losa et al., 2019).
3.2 Cardiovascular, Gastrointestinal, and Systemic Effects
Animal and human studies have reported additional adverse events. Stohs (2014) notes that gastrointestinal disturbances including nausea, bloating, diarrhea, and stomach upset have been reported, particularly when taken on an empty stomach or at high doses. Cardiovascular effects have also been observed, with animal studies revealing that at low concentrations, Shilajit lowered heart rate, while at high concentrations, it increased heart rate (Stohs, 2014). Reported side effects in clinical trials include skin redness, increased blood pressure, disorientation, dizziness, and cognitive disorder (Stohs, 2014).
3.3 Drug Interactions and Contraindicated Populations
Several potential drug interactions raise safety concerns. Shilajit may increase testosterone levels, which could heighten side effects of other testosterone boosters and potentially reduce the effectiveness of estrogen-based medications. Rat studies indicate possible protection of gastric mucosa when taken with aspirin, but human data are lacking (Stohs, 2014). Based on available evidence, Shilajit is contraindicated in several populations: pregnant and breastfeeding women due to heavy metal transfer; individuals with hormone-sensitive cancers due to potential testosterone elevation; patients with hemochromatosis or chronic kidney disease; and individuals with mast cell activation syndrome who face increased risk of severe allergic reactions (Losa et al., 2019; Stohs, 2014).
4. The Efficacy Evidence Gap
Despite aggressive marketing claims positioning Shilajit as an energy enhancer, testosterone booster, and cognitive function improver, the scientific evidence base remains remarkably limited and characterized by methodological weaknesses.
4.1 Testosterone-Related Studies
A randomized, double-blind, placebo-controlled clinical study evaluated purified Shilajit in healthy volunteers aged 45–55 years at a dose of 250 mg twice daily for 90 days. The study found that treatment with Shilajit significantly increased total testosterone, free testosterone, and dehydroepiandrosterone (DHEAS) compared with placebo (P < 0.05), while gonadotropic hormone levels were well maintained. However, this study was limited by its small sample size, specific older male population, and lack of long-term follow-up data (Pandit et al., 2016). More recent randomized controlled trials have reported similar findings, but these require replication in larger, independent studies (Stohs, 2014).
4.2 Cognitive and Energy-Related Evidence
The evidence for cognitive and energy-enhancing effects is even more limited. While some studies have suggested potential neuroprotective effects, human studies remain scarce (Carrasco-Gallardo et al., 2012). Wilson et al. (2011) concluded that while many traditional uses exist, there is a lack of well-designed, independent clinical trials to substantiate these claims. The U.S. Department of Defense has noted that very little information from well-designed, independent research studies supports the marketing claims made about Shilajit products (as cited in Stohs, 2014).
4.3 Systematic Review Findings
A comprehensive systematic review by Wilson et al. (2011) emphasized that Shilajit represents an intersection of traditional medicine and modern science, but noted that its complex composition demands rigorous scientific exploration. The review highlighted the critical need for comprehensive assessment of clinical efficacy and safety. Although research studies on using up to 500 mg of Shilajit extract suggest short-term safety, the possible exposure to heavy metals is a concern that has not been adequately addressed in existing efficacy studies (Stohs, 2014; Wilson et al., 2011).
5. Regulatory Landscape and Safety Gaps
5.1 United States Food and Drug Administration Actions
The U.S. Food and Drug Administration (FDA) has taken multiple enforcement actions against Shilajit products. In June 2009, the FDA issued a Warning Letter to Banyan Trading Company regarding its Shilajit products, which were promoted for conditions including impotence, lung disorders, and urinary tract disorders, classifying the product as a drug under 21 U.S.C. § 321(g)(1)(B). Claims regarding anti-inflammatory and antiviral actions were deemed therapeutic claims requiring FDA approval (U.S. Food and Drug Administration, 2009). More recently, on March 31, 2020, the FDA issued a Warning Letter to a dietary supplement firm for making unapproved disease claims, including references to treatment of diabetes, skin diseases, and heart ailments. The FDA considered citations to scientific publications about Alzheimer's disease and diabetes as evidence of intended drug use, demonstrating the agency's broad interpretation of what constitutes a drug claim (U.S. Food and Drug Administration, 2020).
5.2 Philippine Food and Drug Administration Actions
The Philippine FDA has issued multiple Public Health Warnings against unregistered Shilajit-containing products. FDA Advisory No.2025-1407 warned the public against the unregistered food supplement "KIRKLAND SIGNATURE Gold Grade Shilajit+ 10:1 Extract," while FDA Advisory No.2025-1406 warned against "KIRKLAND SIGNATURE Panax Ginseng Shilajit Ginkgo 3 in 1 Supplement." The FDA verified through post-marketing surveillance that these products were not registered and had no corresponding Certificate of Product Registration. The key rationale was that since it cannot assure the product's quality and safety, the products should not be distributed (Philippine Food and Drug Administration, 2025a, 2025b).
5.3 Health Canada Regulatory Framework
In Canada, Shilajit is classified as a Class 3 Natural Health Product under Schedule 1, item 2 of the Natural Health Products Regulations. Products must obtain a Natural Product Number license, with a turnaround time of 7 to 10 months. Bilingual labeling is mandatory, and foreign manufacturers must partner with a Health Canada site-licensed importer. Regarding quality specifications, Shilajit must meet the finished product specifications for heavy metals outlined in the NNHPD Quality of Natural Health Products Guide. Shilajit must have undergone a purification process, and daily doses of minerals must not exceed the maximum daily doses per the NNHPD Multi-Vitamin/Mineral Supplements monograph (Health Canada, n.d.).
6. Comparative Regulatory Analysis and Specific Concerns for Energy Drinks
The use of Shilajit in energy drinks magnifies existing concerns in several critical ways. First, regarding cumulative heavy metal exposure, energy drinks are consumed regularly, often daily, and the thallium bioaccumulation risk increases with frequency and duration of use, meaning that regular consumers face a substantially higher cumulative toxic metal burden than occasional users (Kamgar et al., 2025). Second, batch inconsistency presents a significant challenge, as each production batch may have different heavy metal content due to the natural variability inherent in Shilajit sourcing (Kamgar et al., 2025). Third, the potential for synergistic toxicity with caffeine and other stimulants found in energy drinks is entirely unstudied, creating unknown health risks for consumers. Fourth, energy drinks are marketed to younger demographics, potentially increasing lifetime cumulative exposure to heavy metals. Fifth, the core reason for Shilajit's inclusion in energy drinks—purported energy enhancement—lacks independent clinical validation (Wilson et al., 2011; Stohs, 2014). The absence of established safe daily intake limits for thallium, combined with the lack of long-term safety data, makes regular consumption of Shilajit-containing energy drinks particularly concerning from a public health perspective (Kamgar et al., 2025).
7. Conclusions
The evidence reviewed in this manuscript establishes several critical conclusions regarding the safety of Shilajit, particularly when used in energy drinks.
First, thallium contamination in Shilajit is scientifically documented, with commercial supplements showing concentrations up to 0.5 µg/g—higher than crude Shilajit. Thallium is a highly toxic metal with mutagenic, carcinogenic, and teratogenic properties, and the absence of established safe daily intake limits makes chronic consumption particularly concerning (Kamgar et al., 2025).
Second, Shilajit contains numerous toxic metals including arsenic, lead, cadmium, and mercury, with documented health risks including cancer and organ damage (Wilson et al., 2011; Stohs, 2014).
Third, documented adverse effects include life-threatening anaphylaxis, cardiovascular effects, blood pressure changes, skin reactions, and gastrointestinal disturbances (Losa et al., 2019; Stohs, 2014).
Fourth, claims of energy enhancement, testosterone boosting, and cognitive improvement lack robust, independent clinical validation. Available studies are small, limited in duration, and often industry-funded (Pandit et al., 2016; Wilson et al., 2011).
Based on current scientific evidence, regular consumption of Shilajit-containing energy drinks cannot be recommended. The documented risks of heavy metal contamination, particularly thallium, combined with the lack of proven efficacy and inadequate regulatory oversight in many jurisdictions, present an avoidable public health concern. Until robust safety standards and independent efficacy data are established, regulatory authorities should not permit Shilajit's use in products intended for daily consumption.
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