Nitrous oxide (N₂O) is an anesthetic gas, also consumed for its euphoric properties, which can cause serious health problems. In this report, we present the case of a 23-year-old man who has been regularly consuming this gas since 2018, with a progressive intensification of his consumption, leading to subacute myeloneuropathy. Given a similar context, a previous diagnosis of Guillain-Barré syndrome in 2021 is questioned. We review the laboratory tests to be performed in the management of a patient presenting motor and sensory neuropathies associated with N₂O consumption, namely homocysteine and methylmalonic acid (MMA) assays.