Template:NBOMeOD

Due to the very high potency and seemingly unpredictable effects the margin between a normal and an overdose of NBOMe compounds is extremely small when compared to many other substances. The exact toxic dose is unclear since it seems to depend a lot on personal physiology, rather than predominantly dose. However, various anecdotal reports suggest that dangerous side effects begin to appear when exceeding 1000 μg and it possibly becoming lethal for the more sensitive people at roughly 2000 μg. Reports of other people surviving much higher doses, sometimes even without any major side effects have been documented as well.

There is also the uncertainty of dosage on blotter paper since it is rather difficult to lay such an exact dosage. Insufflating, vaporizing or drinking tinctures of this substance is highly discouraged because of this and has been tied to many documented deaths. One study found that 25I‐NBOMe and 25C‐NBOMe blotter papers contained 'hotspots' with higher quantities of the drug, implying an inherent risk of overdosing.

The overdose effects of NBOMes are typically a dangerously high heart rate, blood pressure, hyperthermia and significant vasoconstriction also accompanied by confusion, delusions, panic attacks, aggressive behavior, numbness or pain, amnesia and often seizures. The risks in an overdose include anything from organ failure to cardiac arrest and death. There are also multiple reports of people lethally injuring themselves or falling to death. Benzodiazepines or antipsychotics can help with the psychological effects during an overdose although medical attention should always be called in even a possible overdose of 25I-NBOMe.