Rarely, distorted taste or other taste dysfunction can be an early symptom of a significant or life-threatening condition, such as amyotrophic lateral sclerosis (ALS), multiple sclerosis, lung cancer, myasthenia gravis, or coronavirus disease 2019 (COVID-19).[11]Wrobel BB, Leopold DA. Clinical assessment of patients with smell and taste disorders. Otolaryngol Clin North Am. 2004 Dec;37(6):1127-42.
https://www.sciencedirect.com/science/article/pii/S003066650400132X?via%3Dihub
http://www.ncbi.nlm.nih.gov/pubmed/15563906?tool=bestpractice.com
[34]Petzold GC, Einhäupl KM, Valdueza JM. Persistent bitter taste as an initial symptom of amyotrophic lateral sclerosis. J Neurol Neurosurg Psychiatry. 2003 May;74(5):687-8.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1738429/pdf/v074p00687a.pdf
http://www.ncbi.nlm.nih.gov/pubmed/12700324?tool=bestpractice.com
[35]Qiu C, Cui C, Hautefort C, et al. Olfactory and gustatory dysfunction as an early identifier of COVID-19 in adults and children: an international multicenter study. Otolaryngol Head Neck Surg. 2020 Oct;163(4):714-21.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7298561
http://www.ncbi.nlm.nih.gov/pubmed/32539586?tool=bestpractice.com
[13]Thomas DC, Chablani D, Parekh S, et al. Dysgeusia: a review in the context of COVID-19. J Am Dent Assoc. 2022 Mar;153(3):251-64.
https://jada.ada.org/article/S0002-8177(21)00519-5/fulltext
http://www.ncbi.nlm.nih.gov/pubmed/34799014?tool=bestpractice.com
In neurologic disease, taste disorders are often associated with symptoms such as dysphasia, dysphonia, or dysarthria.[62]Landis BN, Lacroix JS. Taste disorders. B-ENT. 2009;5(suppl 13):123-8.
http://www.ncbi.nlm.nih.gov/pubmed/20084813?tool=bestpractice.com
COVID-19 taste disorders are commonly accompanied by loss of the sense of smell.[63]Lechien JR, Chiesa-Estomba CM, Hans S, et al. Loss of smell and taste in 2013 European patients with mild to soderate COVID-19. Ann Intern Med. 2020 Oct 20;173(8):672-5.
https://www.acpjournals.org/doi/10.7326/M20-2428
http://www.ncbi.nlm.nih.gov/pubmed/32449883?tool=bestpractice.com
Particular attention should be given to patients presenting with other neurologic symptoms accompanying taste disorders. In these cases, cranial computed tomography (CT) or magnetic resonance imaging (MRI) scans should be carefully examined to formally exclude any unidentified central nervous system pathology (e.g., tumor, stroke, multiple sclerosis).[46]Heckmann JG, Heckmann SM, Lang CJ, et al. Neurological aspects of taste disorders. Arch Neurol. 2003 May;60(5):667-71.
http://archneur.jamanetwork.com/article.aspx?articleid=784121
http://www.ncbi.nlm.nih.gov/pubmed/12756129?tool=bestpractice.com
A sweet dysgeusia should prompt exclusion of any paraneoplasia (e.g., lung cancer, thymoma).[1]Hsieh JW, Daskalou D, Macario S, et al. How to manage taste disorders. Curr Otorhinolaryngol Rep. 2022;10(4):385-92.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9490708
http://www.ncbi.nlm.nih.gov/pubmed/36158900?tool=bestpractice.com
[57]Panayiotou H, Small SC, Hunter JH, et al. Sweet taste (dysgeusia): the first symptom of hyponatremia in small cell carcinoma of the lung. Arch Intern Med. 1995 Jun;155(12):1325-8.
http://www.ncbi.nlm.nih.gov/pubmed/7778965?tool=bestpractice.com
Serum electrolytes may reveal hyponatremia. In such cases, a chest x-ray and/or CT scan of the lungs should be ordered.
The clinical presentation of COVID-19 is typically with fever, cough, dyspnea, and/or fatigue. Patients may develop a severe viral pneumonia leading to potentially fatal acute respiratory distress syndrome. Patients with suspected COVID-19 infection should be immediately isolated from other patients. Local infection prevention and control procedures should be implemented. See Coronavirus disease 2019 (COVID-19).