Intranasal vitamin A is beneficial in post-infectious olfactory loss

Eur Arch Otorhinolaryngol. 2017 Jul;274(7):2819-2825. doi: 10.1007/s00405-017-4576-x. Epub 2017 Apr 22.

Abstract

Vitamin A plays a decisive role in the regeneration of olfactory receptor neurons. In this retrospective study we investigated the effectiveness of topical vitamin A in patients with post-infectious and posttraumatic smell disorders. Retrospective cohort. A total of 170 patients (age range 18-70 years, mean age 52 years) participated. Forty-six patients were treated with smell training only. The remaining 124 patients received smell training and topical vitamin A. Olfactory function was assessed using the Sniffin' Sticks test kit, a validated technique to measure odor thresholds, discrimination and identification. The duration of olfactory training was 12 weeks. In patients receiving vitamin A, this was applied topically (head back position) at a dose of 10,000 IU/day for 8 weeks. Follow-up testing was performed approximately 10 months after the first assessment. Thirty-seven per cent of all post-infectious patients treated with vitamin A exhibited clinical improvement, whereas only 23% improved in controls. Using a Chi-square test, this was a significant result (χ 2 = 7.06, df = 2, p = 0.03). In addition, when comparing change in score after treatment, olfactory training + vitamin A produced significantly greater improvement compared with training alone, in discrimination score for all patients (1.4 points, p = 0.008), and in threshold and discrimination in the post-infectious group (1.6 points, p = 0.01 and 1.4 points, p = 0.04, respectively). Intranasal vitamin A at a dose of 10,000 IU per day for 2 months may be useful in the treatment of post-infectious olfactory loss. Further work with prospective, placebo-controlled studies is required to confirm these findings.

Keywords: Drug therapy; Hyposmia; Nose; Olfaction; Retinoic acid; Therapeutics; Therapy; Vitamin A.

MeSH terms

  • Administration, Intranasal
  • Adolescent
  • Adult
  • Aged
  • Drug Administration Schedule
  • Female
  • Follow-Up Studies
  • Humans
  • Infections / complications*
  • Male
  • Middle Aged
  • Olfaction Disorders / diagnosis
  • Olfaction Disorders / drug therapy*
  • Olfaction Disorders / etiology
  • Retrospective Studies
  • Treatment Outcome
  • Vitamin A / therapeutic use*
  • Vitamins / therapeutic use*
  • Wounds and Injuries / complications*
  • Young Adult

Substances

  • Vitamins
  • Vitamin A