At food-additive levels guar gum is well tolerated; the EFSA 2017 re-evaluation found no safety concern and set no numerical ADI, matching the long-standing JECFA "ADI not specified." Gram-dose supplemental use can cause dose-dependent GI effects (flatulence, bloating, cramps, loose stools) as it ferments. The landmark safety signal is mechanical, not toxicological: dehydrated, concentrated guar gum in "Cal-Ban 3000"-type diet tablets swells 10-20 fold on contact with fluid, and an FDA case series documented 18 esophageal and 7 small-bowel obstructions plus one death, leading FDA to ban guar gum in OTC weight-loss drugs in 1992 — anyone taking bulk guar fiber should take it with ample water and avoid it with esophageal strictures or swallowing/motility disorders. There is no credible evidence of carcinogenicity or systemic toxicity; EFSA flagged only that abdominal discomfort in infants/young children should be monitored. People with galactomannan/legume sensitivities are theoretically at risk of allergic reaction, and viscous fiber can slow absorption of co-administered oral drugs. Educational only — always check with your doctor or pharmacist before combining Guar Gum with any medicine.