Nail biting

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Nail biting
Classification and external resources
Nail and cuticle bitting.JPG
Fingers of a nail-biter.
ICD-10F98.8 (ILDS F98.810)
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Nail biting
Classification and external resources
Nail and cuticle bitting.JPG
Fingers of a nail-biter.
ICD-10F98.8 (ILDS F98.810)

Onychophagia (also onychophagy) or nail biting, is an oral compulsive habit (sometimes described as a parafunctional activity) in children and adults.


Nail biting is considered an impulse control disorder in the DSM-IV-R, and is classified under obsessive-compulsive and related disorders in the DSM-5. The ICD-10 classifies it as "other specified behavioral and emotional disorders with onset usually occurring in childhood and adolescence."[1]

Signs and symptoms[edit]

Biting nails can lead to broken skin on the cuticle. When cuticles are improperly removed, they are susceptible to microbial and viral infections such as paronychia. Saliva may then redden and infect the skin.[2]

Nail biting is also related to dental problems, such as gingival injury and malocclusion of the anterior teeth.[3][4]

It can also transfer pinworms or bacteria buried under the surface of the nail from the anus region to the mouth.[5][6] When the bitten-off nails are swallowed, stomach problems can develop.[4]

Fingernails may become severely deformed after years of nail biting.[7]

Related disorders[edit]

Related body-focused repetitive behaviors include dermatillomania (skin picking), dermatophagia (skin biting), and trichotillomania (the urge to pull out hair).[8] Nail biting appeared in a study to be more common in men with eating disorders than those without them.[9] It is also more common among children and adolescents with obsessive–compulsive disorder.[10] Nail biting is an oral parafunctional activity, and may be associated with bruxism (tooth clenching and grinding), and other habits such as pen chewing and morsicatio buccarum (cheek biting).[11]


The most common treatment, which is cheap and widely available, is to apply a clear, bitter-tasting nail polish to the nails. Normally denatonium benzoate is used, the most bitter chemical compound known. The bitter flavor discourages the nail-biting habit.[12]

Behavioral therapy is beneficial when simpler measures are not effective. Habit Reversal Training (HRT), which seeks to unlearn the habit of nail biting and possibly replace it with a more constructive habit, has shown its effectiveness versus placebo in children and adults.[13] In addition to HRT, stimulus control therapy is used to both identify and then eliminate the stimulus that frequently triggers biting urges.[14]

Finally nail cosmetics can help to ameliorate nail biting social effects.[15]


About 30 percent of children between 7 and 10 years of age and 45 percent of teenagers engage in nail biting.[2] The ten fingernails are usually equally bitten to approximately the same degree.[2] It may be underrecognized since individuals tend to deny or be ignorant of its negative consequences, complicating its diagnosis.[8]


  1. ^ "Impulse control disorder". SteadyHealth. 30 December 2010. Retrieved 28 April 2012. 
  2. ^ a b c Leung AK, Robson WL (1990). "Nailbiting". Clin Pediatr (Phila) 29 (12): 690–2. doi:10.1177/000992289002901201. PMID 2276242. 
  3. ^ Krejci CB (June 2000). "Self-inflicted gingival injury due to habitual fingernail biting". J. Periodontol. 71 (6): 1029–31. doi:10.1902/jop.2000.71.6.1029. PMID 10914808. 
  4. ^ a b Tanaka OM, Vitral RW, Tanaka GY, Guerrero AP, Camargo ES (August 2008). "Nailbiting, or onychophagia: a special habit". Am J Orthod Dentofacial Orthop 134 (2): 305–8. doi:10.1016/j.ajodo.2006.06.023. PMID 18675214. 
  5. ^ Sung JF, Lin RS, Huang KC, Wang SY, Lu YJ (November 2001). "Pinworm control and risk factors of pinworm infection among primary-school children in Taiwan". Am. J. Trop. Med. Hyg. 65 (5): 558–62. PMID 11716114. 
  6. ^ Baydaş B, Uslu H, Yavuz I, Ceylan I, Dağsuyu IM (2007). "Effect of a chronic nail-biting habit on the oral carriage of Enterobacteriaceae". Oral Microbiol. Immunol. 22 (1): 1–4. doi:10.1111/j.1399-302X.2007.00291.x. PMID 17241163. 
  7. ^ Jabr FI (September 2005). "Severe nail deformity. Nail biting may cause multiple adverse conditions". Postgrad Med 118 (3): 37–8, 42. PMID 16201307. 
  8. ^ a b Bohne A, Keuthen N, Wilhelm S (2005). "Pathologic hairpulling, skin picking, and nail biting". Ann Clin Psychiatry 17 (4): 227–32. doi:10.1080/10401230500295354. PMID 16402755. 
  9. ^ Mangweth-Matzek B, Rupp CI, Hausmann A, Gusmerotti S, Kemmler G, Biebl W (2010). "Eating disorders in men: current features and childhood factors". Eat Weight Disord 15 (1–2): e15–22. PMID 20571316. 
  10. ^ Grant JE, Mancebo MC, Eisen JL, Rasmussen SA (January 2010). "Impulse-control disorders in children and adolescents with obsessive–compulsive disorder". Psychiatry Res 175 (1–2): 109–13. doi:10.1016/j.psychres.2009.04.006. PMC 2815218. PMID 20004481. 
  11. ^ Cawson RA, Odell EW, Porter S. (2002). Cawson's essentials of oral pathology and oral medicine. (7th ed.). Edinburgh: Churchill Livingstone. p. 66. ISBN 0443071063. 
  12. ^ Allen KW (March 1996). "Chronic nailbiting: a controlled comparison of competing response and mild aversion treatments". Behav Res Ther 34 (3): 269–72. doi:10.1016/0005-7967(95)00078-X. PMID 8881096. 
  13. ^ Bate, KS; Malouff, JM; Thorsteinsson, ET; Bhullar, N (July 2011). "The efficacy of habit reversal therapy for tics, habit disorders, and stuttering: a meta-analytic review.". Clinical psychology review 31 (5): 865–71. doi:10.1016/j.cpr.2011.03.013. PMID 21549664. 
  14. ^ Penzel, Fred. "Skin picking and nail biting: related habits". Western Suffolk Psychological Services. Retrieved 2008-03-22. 
  15. ^ Iorizzo M, Piraccini BM, Tosti A (March 2007). "Nail cosmetics in nail disorders". J Cosmet Dermatol 6 (1): 53–8. doi:10.1111/j.1473-2165.2007.00290.x. PMID 17348997.