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Novel Insights from Clinical Practice
Skin Appendage Disord 2015;1:141–143
DOI: 10.1159/000441622
Scalp Psoriasiform Contact Dermatitis
with Acute Telogen Effluvium
due to Topical Minoxidil Treatment
MichelangeloLaPlaca RiccardoBalestri FedericoBardazzi
ColombinaVincenzi
Dermatology Division, Department of Experimental, Diagnostic and Specialty Medicine, University of Bologna,
Bologna , Italy
minoxidil was the sole cause of scalp dermatitis, while in the
other patient it was only the vehicle, thus permitting the pa-
tient to continue the treatment for FPHL.
© 2015 S. Karger AG, Basel
Introduction
Topical minoxidil is the only approved treatment for
female pattern hair loss (FPHL), and its use is effective in
most women for the stabilization of hair loss and/or hair
regrowth. Mild pruritus or scaling may be experienced
during the first 1–2 months of treatment due to the fact
that minoxidil induces fast reentry in the anagen of the
Key Words
Minoxidil · Contact dermatitis · Psoriasis · Telogen
effluvium · Scalp · Hair loss · Propylene glycol
Abstract
Topical minoxidil, the only approved treatment for female
pattern hair loss (FPHL), has been associated with scalp al-
lergic contact dermatitis (ACD). We report the case of 2 fe-
male patients who developed ACD from minoxidil solution
with severe telogen effluvium and psoriasiform scalp derma-
titis. Scalp dermoscopy was useful to identify the psoriasi-
form vascular pattern, whereas patch testing made it possi-
ble to differentiate the cause of sensitization. In one case,
Received: September 25, 2015
Accepted: October 8, 2015
Published online: November 19, 2015
Colombina Vincenzi, Dermatology Division
Department of Experimental, Diagnostic and Specialty Medicine
University of Bologna, Via Massarenti 1
IT–40138 Bologna (Italy)
E-Mail colombina.vincenzi
@ unibo.it
© 2015 S. Karger AG, Basel
2296–9195/15/0013–0141$39.50/0
www.karger.com/sad
Established Facts
• Allergic contact dermatitis (ACD) from minoxidil solution is well known, and several cases have been
reported.
• Scalp ACD may be the cause of telogen effluvium (TE), and patch tests are warranted for diagnosis.
Novel Insight
• We describe 2 cases of psoriasiform ACD of the scalp and severe TE due to minoxidil treatment.
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La Placa/Balestri/Bardazzi/Vincenzi
Skin Appendage Disord 2015;1:141–143
DOI: 10.1159/000441622
142
hair follicles, provoking a transitory telogen effluvium
(TE). If symptoms persist or appear later during the treat-
ment, the occurrence of sensitization to minoxidil or to
the vehicles must be excluded in order to avoid an acute
TE that could compromise the benefits of minoxidil. Al-
lergic contact dermatitis (ACD) from minoxidil solution
is well known, and several cases have been reported where
either minoxidil or propylene glycol have been identified
as the cause of allergy
[1, 2] .
We herein report 2 cases of psoriasiform ACD of the
scalp and acute TE due to minoxidil solution allergy.
Case Presentations
Case 1
A 46-year-old woman with severe FPLH had been under treat-
ment with 2% topical minoxidil (Regaine
®
) for several years. The
patient was referred to our consultation due to her complaining of
a deterioration of her symptoms. We observed diffused alopecia,
with large areas of scaly psoriatic plaques involving almost the en-
tire scalp, extending from the frontal hairline to the vertex ( fig.1 a).
The pull test was strongly positive, and dermoscopic evaluations
( fig.1 b) confirmed the presence of a psoriasiform vascular pattern
characterized by twisted hair loops. According to the patient, the
hair loss had worsened over the last few weeks in association with
a
b
Color version available online
Fig. 1. a Diffuse hair loss with severe scal-
ing and scalp erythema.
b Scalp dermos-
copy of patient 1, showing numerous scales
and vascular twisted loops.
2% minoxidil solution
(with propylene glycol)
5% minoxidil foam
(without propylene glycol)
Propylene
glycol 20% aq.
a b
Color version available online
Fig. 2. a The patch test results in patient 1
shows a positive reaction to her minoxidil
solution and a negative reaction to propyl-
ene glycol.
b The patch test results in pa-
tient 2 reveals a positive reaction to both
her minoxidil solution and propylene gly-
col.
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Psoriasiform Allergic Contact Dermatitis
from Minoxidil
Skin Appendage Disord 2015;1:141–143
DOI: 10.1159/000441622
143
the abrupt appearance of scaly dermatosis. Laboratory investiga-
tions were within the normal range.
Patch tests performed with her personal 2% minoxidil solution
(containing propylene glycol as eccipient), with a 5% minoxidil
foam without propylene glycol (Rogaine
®
foam for men) and with
propylene glycol 20% aq. (Allergopharma S.p.A., Rome, Italy) re-
vealed a positive reaction (2+) to the personal 2% minoxidil solu-
tion and to the 5% minoxidil foam at day 4, with a negative reaction
to propylene glycol ( fig.2 a). Minoxidil treatment was subsequent-
ly discontinued, and topical therapy with clobetasol ointment un-
der occlusion was started. The psoriasiform dermatitis and TE im-
proved within a few weeks.
Case 2
A 28-year-old otherwise healthy female was seen because of
acute diffuse hair loss. She had a 1-year history of FPHL under
treatment with 2% topical minoxidil solution. Routine blood tests
were within the normal limits. Clinical observation and a positive
pull test suggested the diagnosis of TE. Dermoscopic evaluation
showed the presence of numerous scales associated with the typical
psoriatic vascular pattern with twisted loops.
At day 4, patch tests revealed a strong positive reaction (2+) to
her personal 2% minoxidil solution and to propylene glycol, but a
negative reaction to the 5% minoxidil foam ( fig.2 b). In this patient,
propylene glycol, and not minoxidil itself, was likely to be the cause
of sensitization. After complete healing from the psoriasiform der-
matitis, 5% minoxidil foam without propylene glycol was pre-
scribed.
Discussion
TE is a very distressing condition, characterized by in-
creased hair shedding, potentially reversible, without
complete hair loss, usually starting a few months after a
triggering factor, including psychoemotional stress, im-
balanced diet and drug intake. Several cases of TE occur-
ring after an episode of ACD to hair dyes have been pre-
viously described, provoking diffused nonscarring alope-
cia in these patients
[3] .
The acute flare-up of psoriasis is possible after any
trauma, including burns, insect bites, tattooing and sur-
gery, and occurs in about 25% of the psoriatic individuals
under the name of the Koebner phenomenon
[4] . How-
ever, it has never been reported after ACD so far.
We described 2 female patients under treatment with
minoxidil solution for FPHL worsened by the contempo-
raneous presence of scalp psoriasiform ACD and TE. To
the best of our knowledge, this is the first report describ-
ing an acute TE after ACD from minoxidil.
In our patients, the abrupt flare-up of psoriasiform
ACD and acute TE were the main cause of concern and
the reason for seeking our medical advice. Scalp dermos-
copy was useful to identify the psoriasiform vascular pat-
tern
[5] , and patch tests made it possible to differentiate
the cause of sensitization in these 2 cases. In case 1, min-
oxidil was the sole cause of scalp dermatitis, while in case
2 it was only the vehicle, thus permitting us to continue
the treatment for FPHL.
Although without a scalp biopsy it is impossible to def-
initely establish whether it is psoriasis koebnerized by
contact allergy or a psoriasiform allergic reaction, it is im-
portant for the dermatologist to recognize that a minoxi-
dil treatment allergy may be the cause of scalp psoriasi-
form ACD followed by acute TE with severe hair loss, and
that patch tests are warranted for diagnosis.
Statement of Ethics
Consent was obtained from the patients.
Disclosure Statement
There are no conflicts of interest to disclose.
References
1 Hagemann T, Schlütter-Böhmer B, Allam JP,
et al: Positive lymphocyte transformation test
in a patient with allergic contact dermatitis of
the scalp after short-term use of topical min-
oxidil solution. Contact Dermatitis 2005;
33:
53–55.
2 Friedman ES, Friedman PM, Cohen DE, et al:
Allergic contact dermatitis to topical minoxi-
dil solution: etiology and treatment. J Am
Acad Dermatol 2002;
46: 309–312.
3 Tosti A, Piraccini BM, van Neste DJJ: Telogen
effluvium after allergic contact dermatitis of
the scalp. Arch Dermatol 2001;
137: 187–190.
4 Sagi L, Trau H: The Koebner phenomenon.
Clin Dermatol 2011;
29: 231–236.
5 Ross EK, Vincenzi C, Tosti A: Videodermos-
copy in the evaluation of hair and scalp disor-
ders. J Am Acad Dermatol 2006;
55: 799–806.
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