Dermatology: Practical and Conceptual


Image Letter | Dermatol Pract Concept. 2023;13(3):e2023157 1

Xanthonychia Due to Staining  
From Carbidopa-Levodopa

Jonathan Kyle Hwang1, Shari R Lipner1

1 Weill Cornell Medicine, New York, USA

Citation: Hwang, JK, Lipner SR. Xanthonychia Due to Staining from Carbidopa-Levodopa. Dermatol Pract Concept. 
2023;13(3):e2023157. DOI: https://doi.org/10.5826/dpc.1303a157

Accepted: January 17, 2023; Published: July 2023

Copyright: ©2023 Hwang et al. This is an open-access article distributed under the terms of the Creative Commons Attribution-
NonCommercial License (BY-NC-4.0), https://creativecommons.org/licenses/by-nc/4.0/, which permits unrestricted noncommercial use, 
distribution, and reproduction in any medium, provided the original authors and source are credited.

Funding: None.

Competing interests: Author JKH has no conflicts of interest. Author SRL has served as a consultant for Hoth Therapeutics, Ortho-
Dermatologics, Belle Torus Corporation and Moberg Pharmaceuticals.

Authorship: All authors have contributed significantly to this publication.

Corresponding author: Shari R. Lipner MD, PhD, 1305 York Avenue, New York, NY 10021, (646) 962-3376, shl9032@med.cornell.edu

Case Presentation

An 84-year-old female with a history of Parkinson disease 

presented with yellow discoloration of her fingernails for a 

few months. She had been taking carbidopa-levodopa for 

her Parkinson disease for many years, crushing the tablets 

into smaller pieces before ingesting. Physical examination 

was significant for a contracted left hand, xanthonychia 

of all 10 fingernails, and crumbling of the left fingernails  

(Figure 1). A clipping of the fingernails was performed to 

rule out onychomycosis and psoriasis as etiologies.

Teaching Point

In this case, the yellow nail discoloration was due to exoge-

nous pigment from crushing and handling of her carbidopa- 

levodopa medication. The yellow dye from the pill mixes 

with saliva and drips onto the patient’s fingernails, which 

was demonstrated to the authors during the clinic visit.  

The differential diagnosis for yellow discoloration of the 

nails includes onychomycosis, nail psoriasis, nail lichen 

planus, and yellow nail syndrome [1]. Our case stresses the 

importance of considering exogenous causes in diagnosing 

xanthonychia. The carbidopa-levodopa pills our patient 

was prescribed contain D&C yellow no. 10 aluminum lake, 

which give the pills a yellow appearance and has been pre-

viously associated with maculopapular rashes of the trunk 

and arms [2]. As carbidopa-levodopa can cause xanthony-

chia, patients should be counseled to wear gloves if they are 

chewing and handling the medication.

References

1. Vignes S, Baran R. Yellow nail syndrome: a review.  Orphanet 

J Rare Dis. 2017;12(1):42. DOI: 10.1186/s13023-017-0594-4. 

PMID: 28241848. PMCID: PMC5327582.

2. Anang JBM. Levodopa-Carbidopa-Related Rash in Parkinson's 

Disease: A Case Series. Can J Neurol Sci. 2018;45(5):588-589. 

DOI:10.1017/cjn.2018.58 PMID: 30033887.



2 Image Letter | Dermatol Pract Concept. 2023;13(3):e2023157

Figure 1. Xanthonychia of fingernails due to staining from carbidopa-levodopa.