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Int J Audiol. 2019 Mar;58(3):151-157. doi: 10.1080/14992027.2018.1543961. Epub 2019 Jan 17.

Treatment of military acoustic accidents with N-Acetyl-L-cysteine (NAC).

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a Audiology Department , Habilitering & Hälsa, Region Västra Götaland , Gothenburg , Sweden.
b Department of Health and Rehabilitation, Division of Audiology , Institute of Neuroscience and Physiology, University of Gothenburg , Gothenburg , Sweden.
c Armed Forces Centre for Defense Medicine , Gothenburg , Sweden.
d Department of Clinical Science, Unit of Audiology , Intervention and Technology, Karolinska Institute , Stockholm , Sweden.



To study if the antioxidant (AO) N-Acetyl-L-cysteine (NAC) reduces the risk of hearing loss after acoustic accidents in humans.


A retrospective, observational study.


Personnel of the Swedish Armed Forces (SAF) exposed to military acoustic accidents during a 5 year period. Included in the study were 221 cases (mean age: 22.9 years). Most of the exposures, 84%, were weapon related. NAC (400 mg) was given directly after the accident in 146 cases; 75 had not received NAC.


The prevalence of hearing thresholds ≥25 dB HL, and the incidence of threshold shifts ≥10 dB, was lower in the NAC group than in the non-NAC group directly after the noise exposure. The deterioration was temporary and not discernable a long time after the accident. The difference was most pronounced in the right ear. The risk reduction to get a temporary hearing loss (TTS), affecting one or both ears was 39% (significant) in the NAC group.


The study has demonstrated a significant reduction of the incidence of TTS by the use of NAC. Since cases of both permanent hearing loss (PTS) and noise-induced tinnitus are recruited from cases with TTS, the demonstrated risk reduction indicates a positive effect of NAC.


Acoustic trauma; Swedish Armed Forces (SAF); antioxidant (AO); noise-induced hearing loss (NIHL); permanent threshold shift (PTS); relative risk (RR); temporary threshold shift (TTS)

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