Safety Profile
Overall safety rating: Generally Safe
Sulforaphane Side Effects & Safety
Evidence:Moderate
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Potential Side Effects
- GI symptoms (gas, bloating, diarrhea) — the most common side effect, typical of cruciferous compounds
- Thyroid concerns — high doses of cruciferous isothiocyanates may theoretically interfere with iodine uptake; likely insignificant at supplement doses with adequate iodine intake
- Sulfurous taste and odor (burping)
- Generally well-tolerated in clinical trials
Drug & Supplement Interactions
- Thyroid medications — theoretical interaction with iodine uptake at very high doses; likely insignificant at standard supplement doses
- CYP1A2 substrates — sulforaphane induces CYP1A2, potentially reducing blood levels of caffeine, theophylline, and some antidepressants
- Acetaminophen — sulforaphane enhances phase II detoxification which processes acetaminophen; may alter its metabolism
Maximum Dose
Do not exceed: 120mg/day (limited safety data above this level)
References
- RCTEgner PA, Chen JG, Zarth AT, et al. (2014). Rapid and sustainable detoxication of airborne pollutants by broccoli sprout beverage: results of a randomized clinical trial in China. Cancer Prevention Research. DOI PubMed
- RCTAxelsson AS, Tubbs E, Mecber B, et al. (2017). Sulforaphane reduces hepatic glucose production and improves glucose control in patients with type 2 diabetes. Science Translational Medicine. DOI PubMed
- RCTSingh K, Connors SL, Macklin EA, et al. (2014). Sulforaphane treatment of autism spectrum disorder (ASD). Proceedings of the National Academy of Sciences. DOI PubMed
- Meta-analysisGuo J, Wang Y, He W, Lou M, et al. (2025). Effects of sulforaphane on ABC and SRS scales in patients with autism spectrum disorder: a meta-analysis.. Brain & development. DOI PubMed
- Meta-analysisKassar O, M Mansour ME, Farag N, Selim A, et al. (2025). Efficacy and safety of sulforaphane in schizophrenia: a systematic review and meta-analysis of randomized controlled trials.. BMC psychiatry. DOI PubMed
- Long J, Liao X, Tang Z, Han K, et al. (2025). Investigating the clinical efficacy, safety and molecular mechanism of sulforaphane in autism spectrum disorder: an integrated study combining meta-analysis, network pharmacology, and computational biology.. BMC pharmacology & toxicology. DOI PubMed
- Monteiro EB, Ajackson M, Stockler-Pinto MB, Guebre-Egziabher F, et al. (2023). Sulforaphane exhibits potent renoprotective effects in preclinical models of kidney diseases: A systematic review and meta-analysis.. Life sciences. DOI PubMed
Show 4 more references
- Gianfredi V, Vannini S, Moretti M, Villarini M, et al. (2017). Sulforaphane and Epigallocatechin Gallate Restore Estrogen Receptor Expression by Modulating Epigenetic Events in the Breast Cancer Cell Line MDA-MB-231: A Systematic Review and Meta-Analysis.. Journal of nutrigenetics and nutrigenomics. DOI PubMed
- Koushki D, Latifi S, Norouzi Javidan A, Matin M (2015). Efficacy of some non-conventional herbal medications (sulforaphane, tanshinone IIA, and tetramethylpyrazine) in inducing neuroprotection in comparison with interleukin-10 after spinal cord injury: A meta-analysis.. The journal of spinal cord medicine. DOI PubMed
- Conzatti A, Fróes FC, Schweigert Perry ID, Souza CG (2014). Clinical and molecular evidence of the consumption of broccoli, glucoraphanin and sulforaphane in humans.. Nutricion hospitalaria. DOI PubMed
- Cascajosa-Lira A, Prieto AI, Pichardo S, Jos A, et al. (2024). Protective effects of sulforaphane against toxic substances and contaminants: A systematic review.. Phytomedicine : international journal of phytotherapy and phytopharmacology. DOI PubMed