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Antipsychotic treatment of primary delusional parasitosis: Systematic review

  • Peter Lepping (a1), Ian Russell (a2) and Roland W Freudenmann (a3)



Little is known about the treatment of delusional parasitosis with typical and atypical antipsychotics.


To evaluate the effectiveness of typical and atypical antipsychotics in primary delusional parasitosis (delusional disorder, somatic type).


A systematic review was conducted.


No randomised trials were found and hence we collected the best evidence from 16 other trials and case reports, separating primary from other forms of delusional parasitosis. Studies using typical antipsychotics showed partial or full remission in between 60 and 100% of patients. Analysis of selected patients with primary delusional parasitosis showed that typical and atypical antipsychotics were effective in the majority, but that remission rates did not differ significantly between typical and atypical antipsychotics.


In the absence of controlled trials there is limited evidence that antipsychotics are effective in primary delusional parasitosis. Rigorous studies are needed to evaluate their effectiveness and to compare typical and atypical antipsychotics directly.

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Corresponding author

Dr Peter Lepping, North Wales Section of Psychological Medicine, Wrexham Academic Unit, Technology Park, Wrexham, LL13 7YP, UK. Email:


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Declaration of interest

PL. has received fees from Lilly, Otsuka and Astra Zeneca for educational talks.



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Antipsychotic treatment of primary delusional parasitosis: Systematic review

  • Peter Lepping (a1), Ian Russell (a2) and Roland W Freudenmann (a3)


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Antipsychotic treatment of primary delusional parasitosis: Systematic review

  • Peter Lepping (a1), Ian Russell (a2) and Roland W Freudenmann (a3)
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Successful treatment of methamphetamine-induced delusional parasitosis with sertindole and sertralin

Frank Hanisch, neurologist
07 December 2009

1 Klinik und Poliklinik für Psychiatrie, Psychotherapie und Psychosomatik, Martin-Luther-Universität Halle-Wittenberg, Julius-Kühn-Str. 7, 06097 Halle (Saale), Germany2 Klinik und Poliklinik für Neurologie, Martin-Luther-Universität Halle-Wittenberg, Ernst-Grube-Str. 40, 06120 Halle (Saale), Germany

Lepping et al. reviewed the effect of typical and atypical antipsychotics in delusional parasitosis and found only single case reports for the treatment with atypical neuroleptics risperdone, olanzapine, quetiapine, amisulpride, and aripiprazole, resulting mostly inpartial remission (1). We would like to add the report about a patient with methamphetamine-induced delusional parasitosis successfully treated with sertindole and sertraline.

A 22-year old white male with a history of illicite drug abuse between age 11 and 20 including alcohol, cannabis, glue, ecstacy, LSD, cocaine, heroine, and methamphetamin (crystal; ½ g up to 2 g per day, between age 16 to 20) and now drug-free man presented with a three-year history of delusional parasitosis. It was first induced by methamphetamineconsumption and then persisting. He believed that beetles had entered his body via his anus and were spreading and proliferating in his bowles and crawling beneath his skin and inside his mouth causing unpleasant feelingsand pain. There had been neither pruritus, nor selfinjuring behaviour. In addition he showed symptoms of a comorbid generalized anxiety disorder. Hehad been unsuccessfully treated previously with risperidone (extrapyramidal symptoms), aripiprazole (tremor, crampi), clozapine (leucopenia), olanzapine (insufficient response, massive weight gain), amisulpride (gynaecomastia), paliperidone (insufficient response). He was initially treated with lorazepame, and could than be stabilized with a combination of sertindole (20 mg/d) and sertraline (100 mg/d) with normal ECG controls over the course. The pharmacological treatment was combined with cognitive behavioural therapy and desensitization. A previous combination of sertindol (20/d) and escitalopram (20mg/d) was discontinueddue to increased OTc intervall up to 495ms. The patient completely recovered from these tactile hallucinations within two months.

Delusional parasitosis is well-known in methamphetamine and cocaine consumers, nonetheless, medical reports about drug-induced delusional parasitosis are rare (2,3). Sertindole has been also previously reported to be beneficial in a geriatric patient with tactile hallucinations (4). The atypical neuroleptic sertindole in combination with sertraline might be a pharmacological option for patients with delusional parasitosis in which treatment with other drugs was not successful.

References1. Lepping P, Russell I, Freudenmann RW (2007). Antipsychotic treatment ofprimary delusional parasitosis. Br J Psychiatry 191: 198-205

2. Brewer JD, Meves A, Bostwick JM, Hamacher KL, Pittelkow MR (2008).Cocaine abuse: Dermatologic manifestations and therapeutic approaches. J Am Acad Dermatol 59: 346-7

3. Ellinwood EH Jr (1967). Amphetamine psychosis. I. Description of the individuals and processes. J Nerv Ment Dis 144: 273-283

4. Yorston G (1997) Treatment of delusional parasitosis with sertindole. Int J Geriatr Psychiatry 12 (11): 1127-8
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Conflict of interest: None Declared

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DP, Very rare or ill reported condition......

Ravimal Galappaththi, DCP, MRCPsych
24 January 2009

I read this article with much interest and would like to share my experience. Due to the rarerity of presentation and not being due to diagnosed, DP is not well reported across medical journals and community. The exact incidence in not known. It is important to bear in mind that DP is a psychiatric symptom rather than a diagnosis, the symptom of being convinced that the person is being infested by some form of parasites.

We have recently reported two presentations suggestive of DP. Both cases initially have presented to their local GPs and first were treated with anti histamines and the second with vermox. Both patients did not improve with treatment and continued to experience the skin irritation andshowed an abnormal conviction that parasites were causing them. Both patient’s fixity and unshakability of beliefs were within the definition of a delusion. In one of the clients, development of conviction to delusional intensity was gradual mainly contributed by the pruritic skin irritation, and other was delusional at onset. Of note is that there was evidence of some degree of sharing of the belief by the partner of one of the clients. Shared delusions were documented in 5-15% of patients with DP. As patients with DP mostly contact dermatologist, GPs and public health doctors, wider knowledge among the medical doctors about the condition is essential. Documented cases before identification have variedbetween 2 months to 35 years, with a mean duration of 3.5 years (2), how ever both our clients were in remission within 6 weeks, after treatment with Risperidone.

Bhatia et al concluded that 88% of cases with DP were above 45 years and majority were women. Both of our patients were women in their mid fifties. Some studies report onset is insidious with a chronic course; however DP occurred suddenly in both our clients. This could have been dueto prompt psychiatric diagnosis and treatment. It is now known that early diagnosis and antipsychotic treatment makes a difference, and this has been well documented in a systemic review in British journal of psychiatry. (1) In both our patients’ remission of symptoms was noted within few days to two weeks of starting a trial of low dose risperidone. In both patients there was no significant past psychiatric history, and screening for psychiatric disorders at the time of assessment was negative. However we were unable to exclude an adjustment disorder, given the history of precipitating stressors, and mixture of affective and anxiety symptoms at the time of presentation. Medical causes were excludedwith biochemical screen, MRI studies ect..One of them was significantly socially isolated, which is a documented relationship in many clients. Interestingly both patients had a history of atopic allergy, obsessive compulsive traits but I couldn’t capture literature stating the relationship.

DP probably appear to be related to neurochemical change, the very reason why DP is precipitated by, cocaine “cocaine bug”, amphetamines, alcohol ect. This theory is also confirmed by its coincidence with axis 1 disorders such as schizophrenia, major depression, and sensory impairment,and also by neurotransmitter secreting space occupying lesions in the brain.

DP presents a therapeutic challenge to both patient and the treating physician. Although a fair number of DP patients have a contestable beliefon infestation, they do resist the suggestion that condition is psychiatric. There for its paramount that psychiatrist would not collude or challenge the delusions at least initially. It’s much therapeutic to accept the patients distress and and create a window of opportunity where alliance can be established and work with the patient to accept antipsychotic medication at an earlier stage of disease. Patient’s sense of isolation must be reduced. Patients sense of helplessness need to be born in mind and its not uncommon for these patient to feel suicidal in context of unresolving and frustrating symptoms. A sensible approach and engagement should prevent ‘doctor shopping’ which will reduce the risk of medicalising the problem.

DP is not a culture bound symptom but disorder may have a different character in Asian compared to Caucasian counterparts. For example Indian patients from madras was younger (mean age 36.4), and experienced shorter duration of symptoms (mean 10.4 months). Both of our clients had a complete remission of symptoms in 6 weeks, evidenced by improvement in cognition, mood, social functioning, and reduction of abnormal perceptionsand attached delusions. Remarkable improvement in insight with attributionof symptoms to possible stress was evident in both clients after 2-3 weeks.

Practical Points1.DP is most likely to be a common presentation though less encountered in psychiatric practice and could present to a variety of medical services

2.Basic understanding of the condition and treatment is necessary bypractitioners of all medical Specialities

2.Early referral of chronically symptomatic patients to liaison and other psychiatric services will certainly be helpful to reduce the patientdistress and reduce the chronicity

3.Antipsychotics seem to be effective in most cases with DP, contrairy to delusional disorders possibly indicating a different neuro-biological basis which needs further testing. This is especially evident with Primary DP.

4.Finally, more randomized control trials or Meta analysis of current evidence is needed to strengthen the evidence base

References:1. Peter Lepping, Ian Russell, and Roland W. Freudenmann, Antipsychotic treatment of primary delusional parasitosis: Systematic review, The British Journal of Psychiatry, Sep 2007; 191: 198 - 205.

2. Delusional Parasitosis: case series of 8 patients and review of litereture, JY Thong, DCW Aw, HL Chan, Ann Acad Medi. Singapore 2004;33:89-94
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Considerations of second generation antipsychotics in the treatment of delusional parasitosis

Peter Lepping, Consultant Psychiatrist, Honorary Senior Lecturer, Associate Medical Director
02 July 2008

Dear Sir,

We thank our colleagues Narayan et al for their contribution (eLetterto British Journal of Psychiatry, 9 April 2008) to the discussion around the antipsychotic treatment of primary delusional parasitosis (DP) referring to our recent systematic review in this journal (Lepping, Russell & Freudenmann, 2007).

Narayan et al suggest that the pharmacokinetics (half-life of 60-80 hours) and side effect profile of aripiprazole may make it particularly interesting for the treatment of DP where adherence to and engagement withtreatment are the most significant challenges. They mention a case report of an 85 year-old woman with primary DP, which fully responded to aripiprazole (Rocha & Hara, 2007). Age-adapted doses of 15, later 7.5 mg daily led to full resolution of symptoms after olanzapine had to be stopped because of severe hyponatraemia and pimozide had been abandoned because of extrapyramidal symptoms. Recently Kumbier & Höppner published a second case of aripiprazole use resulting in an almost full remission of symptoms (Kumbier & Höppner, 2007); however, the DP syndrome was secondary to paranoid schizophrenia and not a primary delusional disorder.

It is indeed interesting that our own systematic review in this journal showed that the best response rates were achieved with first generation depot antipsychotics, although this finding was based on a single small study by Frithz, published in 1979. However, other first generation antipsychotics with relatively long half-lives such as pimozide(half-life of 55 hours) or haloperidol (half-life 12-36 hours) did not differ from those first generation antipsychotics with shorter half-lives.Experience with other second generation antipsychotics with long half-lives are limited to one case with partial remission to sertindole (half-life 55-90 hours) (Yorston, 1997) and one recent case treated with paliperidone (half-life 24 hours) from our group (Freudenmann, Kühnlein, Lepping, et al). However, both patients suffered from a DP syndrome secondary to brain pathology or a severe medical condition. Thus, evidencefor the use of antipsychotics with long half lives in DP is very limited, in particular in primary DP, where it is limited to the one case treated with aripiprazole (Rocha & Hara, 2007).

Whilst pharmacokinetic considerations are obviously an important aspect when choosing an antipsychotic for the treatment of DP, efficacy and tolerability are at least equally, if not more important. The level ofefficacy of second generation antipsychotics in DP is less than certain, although the number of cases reporting positive effects is growing constantly. Our own review showed that only 25% of patient treated with a second generation antipsychotic achieved full remission in primary DP.

Two published cases are too few to enable us to make a judgement on the efficacy of aripiprazole in DP, although every case report is welcome because it increases our knowledge. The side effect profile of aripiprazole may be advantageous with regard to the development of metabolic syndrome, but this is often less important in DP because of the often short period of time that patients agree to take medication. Furthermore, the common side effect of insomnia is a real problem with aripiprazole in a patient group that already suffers from agitation and insomnia because of persistent itching.

We therefore agree that medications with long half-life are theoretically promising in DP, as is true for all disorders with poor insight and a tendency to intermittent non-adherence. However, we do not agree that the current evidence available for aripiprazole makes it the substance of choice among the group of second generation antipsychotics inDP despite its favourable pharmacokinetic profile and low risk of metabolic and cardiac complications. There are substantially more successful reports on risperidone (more than n = 30) and olanzapine (more than n = 15) as well as our own positive experience with amisulpride than case reports on aripiprazole in both primary and secondary DP. However, clinical studies, not case reports, will be needed to further establish second generation antipsychotics in DP, and show their individual effects in this syndrome.

Corresponding author: Dr. Peter Lepping, Honorary Senior Lecturer (University of Wales Bangor), Consultant Psychiatrist and Associate Medical Director (North East Wales NHS Trust)Roland W. Freudenmann (University of Ulm)

Declaration of Interest:PL has received honoraria for lecturing from Lilly and Bristol-Myers Squibb, producers of aripiprazole. He has been partially funded by Lilly to attend a conference in 2007. This activity was fully within the rules of CR148. RWF has nothing to declare.


Freudenmann, R. W., Kühnlein, P., Lepping, P., et al Secondary delusional parasitosis treated with paliperidone. Clin Exp Derm (in press).Kumbier, E. & Höppner, J. (2007) Neuroleptische Behandlung des Dermatozoenwahns. Erste Erfahrungen mit Aripiprazol [The neuroleptic treatment of delusional parasitosis : First experiences with aripiprazole.]. Hautarzt, published online Nov 18 2007, DOI 10.1007/s00105-007-1438-2.Lepping, P., Russell, I. & Freudenmann, R. W. (2007) Antipsychotic treatment of delusional parasitosis: systematic review. Br J Psych, 191, 198-205.Rocha, F. L. & Hara, C. (2007) Aripiprazole in delusional parasitosis:Case report. Prog Neuropsychopharmacol Biol Psychiatry, 31, 784-786.Yorston, G. (1997) Treatment of delusional parasitosis with sertindole [letter]. Int J Geriatr Psychiatry, 12, 1127-1128.
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Aripiprazole in the treatment of Primary Delusional Parasitosis

Vinesh Narayan, Specialist Registrar
09 April 2008

The review by Lepping et al(1) points out the difficulty of engaging patients with primary delusional parasitosis (PDP) in psychiatric treatment due to their poor insight. Our clinical experience fully supports this. The authors emphasise the lack of randomised controlled studies in this field and the limited, but promising, anecdotal literatureon the use of atypical antipsychotics. Their systematic review did not identify any reports of aripiprazole in the treatment of PDP. However since this review was accepted for publication, a case report has appearedreporting the successful use of aripiprazole in an 85-year-old woman with PDP(2).

Aripiprazole has a unique pharmacological profile that includes partial agonist activity at dopamine D2 and serotonin 5-HT1A receptors. Ithas a favourable side effect profile relative to other antipsychotics(3). It is not sedating and has little propensity to cause weight gain, extrapyramidal symptoms, prolactin elevation and metabolic disturbance. However it can cause nausea and akathisia in some patients. The favourable tolerability profile may be a particular benefit in PDP as these patients are often reluctant to consider antipsychotic treatment andtolerate medication poorly.

Aripiprazole has a long half-life (approximately 60 hours) compared to other oral antipsychotics(4), which means that occasional missed doses are less likely to impact on clinical outcome. Consequently aripiprazole may be particularly useful when intermitted adherence with medication is aproblem, a situation often encountered in PDP. Interestingly, in the 5 main studies of antipsychotic treatment of PDP identified by Lepping et al1, the highest remission rate (73%) was in the only study that assessed antipsychotic depots(5). Although the small sample sizes limit the value of cross-study comparisons, this result is consistent with the view that medication adherence is poor in PDP and that treatments that can overcome this, in this case a depot antipsychotic, can lead to better outcomes.

In summary, although further evidence is needed to establish the efficacy of aripiprazole in PDP, it seems reasonable to consider this drugwhen discussing treatment choices with patients with PDP.

Competing interests:PMH has received fees for lecturing and consultancy from Bristol Myers Squibb, who manufacture aripiprazole, and the manufacturers of various other antipsychotics.

Vinesh NarayanSpR in General Adult PsychiatryGreater Manchester West Mental Health NHS Foundation

Muhammad AshfaqStaff Grade in General Adult PsychiatryGreater Manchester West Mental Health NHS Foundation Trust

Peter M. HaddadConsultant PsychiatristGreater Manchester West Mental Health NHS Foundation Trust

References:1.Lepping P, Russell I, Freudenmann RW. Antipsychotic treatment of Primary delusional parasitosis. The British Journal of Psychiatry 2007; 191: 198- 2052.Rocha FL, Hara C. Aripiprazole in delusional parasitosis:case report. Progress in Neuro-psychopharmacology and Biological Psychiatry 2007; 31: 784-7863.Haddad PM, Sharma SG. Adverse effects of atypical antipsychotics: differential risk and clinical implications. CNS Drugs 2007: 21(11): 911-36.4.Mallikaarjun S, Salazar DE, Bramer SL. Pharmacokinetics, tolerability, and safety of aripiprazole following multiple oral dosing in normal healthy volunteers. J Clin Pharmacol. 2004; 44(2): 179-87 5.Frithz A. Delusions of infestation: treatment by depot injections of neuroleptics. Clinical and Experimental Dermatology 1979; 4: 485-488
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Old problem, new name?

Kate S Robertson, Staff grade psychiatrist
12 October 2007

The review by Lepping et al (2007) of drug treatments for delusional parasitosis emphasises not only the lack of good quality evidence for treatment with atypical antipsychotics, but also the difficulty in engaging and treating people with this disorder.

I would like to draw attention to the emerging phenomenon of ‘Morgellons’. The name is apparently derived from Sir Thomas Browne (‘…Endemial Distemper of little Children in Languedock, called the Morgellons…’ Letter to a Friend, 1690), and was then more recently appliedto the medically unexplained symptoms suffered by the child of a biologistin the United States. The descriptions of symptoms and possible causes on the Morgellon research foundation website contain marked similarities to definitions of delusional parasitosis; however, the philosophy of the siteis clear- ‘we don’t know what it is but it is not that’. Lepping et al also rightly mention the possibility of alienation of sufferers and the possibility of resort to dangerous self therapies; worryingly, ‘Morgellons’ is described in children as well as adults.

The risks of overenthusiastic ascription of psychiatric causes to physical symptoms have been well documented (eg Slater, 1965), and perhapsin no other branch of medicine is it so important to keep an open mind. Nonetheless, it is also possible that ‘Morgellons’ will on occasion serve as a label for those who are truly deluded as to the presence of parasitesunder their skin. Indeed, it has been argued (by dermatologists) that ‘Morgellons’ be used as a diagnostic label as an aid to establishing rapport (Murase et al) before antipsychotic treatment.

Although ‘Morgellons’ appears to be limited to the United States at present, with all but universal internet access, and in the age of 'cyberchondria', it will be interesting to see if the phenomenon spreads.

Dr Kate Robertson,Staff grade psychiatristHuntercombe Hospital- StaffordIvetsey BankWheaton AstonStaffordshire ST19 9QT

tel. 01785 840000fax. 01785 842192

No competing interests

References:Lepping P, Russell I, Freudenmann RW; Antipsychotic Treatment of Primary Delusional Parasitosis, The British Journal of Psychiatry (2007) 191: 198-205

Slater ET; Diagnosis of ‘hysteria’. BMJ 1965;i:1395 -9

Murase JE, Wu JJ, Koo J; Morgellons disease: a rapport-enhancing termfor delusions of parasitosis, Journal of the American Academy of Dermatology, 2006 Nov;55(5):920-2
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