Tattoos are a popular and increasingly common form of body art [1]. However, with their rising popularity, the risk of various dermatologic complications―such as photosensitivity, infection, trauma related to needle insertion, or allergic response to the pigment―has increased [1-3]. Color pigments, especially red, are frequently cited as the main cause of allergic reactions to tattoos [1-3]. It typically presents as plaque elevation, granulomatous reaction, extensive hyperkeratosis, or ulcerous necrotic change of the tattooed skin, with symptoms of swelling and itching in the affected area [3].

Treatment of allergic reactions to red tattoo dye typically begins with topical or intralesional corticosteroids to reduce inflammation and control symptoms, but the effects are often temporary and unsatisfactory [3,4]. In more severe or persistent cases, lasers or surgical interventions may be employed to completely remove the causative allergens [2-4]. However, there is no consensus on the optimal treatment for allergen removal [4]. We report a case of a refractory allergic reaction to a red tattoo successfully treated with a picosecond neodymium-doped yttrium aluminum garnet (Nd:YAG) laser, followed by fractional carbon dioxide (CO₂) laser and intralesional corticosteroid injection.

A written informed consent was obtained from the patient for the publication of this case report.

A 21-year-old female visited Yonsei Star Skin & Laser Clinic for an irritated, swollen tattoo on her right shoulder. She had gotten the tattoo a year and a half prior, and four months after the procedure, she began experiencing symptoms of swelling and pruritus (Fig. 1A). The itching and swelling disrupted her sleep, significantly affecting her quality of life. Before visiting the clinic, she had received more than ten intralesional injections of triamcinolone acetonide (TA) at four-weeks intervals, with no noticeable improvement. She had no relevant medical history.

Figure 1. (A) Before the treatment. (B) After four treatments, the tattoo was almost removed. (C) After the last treatment session, the lesion completely resolved.

Examination of her right shoulder revealed an erythematous plaque, sharply confined to the area of red tattooed skin. Under a diagnosis of a delayed allergic reaction to the red tattoo pigment, the patient was treated with a picosecond Nd:YAG laser and subsequent fractional CO₂ laser. Then, TA intralesional injection was applied on the tattoo.

Before the treatment, topical lidocaine (SM Cream 9.6%; CellBion Co., Ltd.) was applied for 30 minutes with occlusion. The patient was treated with a picosecond laser (PicoWay^®; Candela^®) at a wavelength 532 nm, a spot size 4 mm, and a fluence of 0.8-1.6 J/cm². The specific fluence used for each session is listed on Table 1. Then, the patient underwent fractional CO₂ laser treatment (Ultrapulse^® Encore; Lumenis) in DeepFx mode with parameters set at 10 mJ of energy and a density of 5%. Lastly, 20 mg/ml of intralesional TA injection was given to the affected area. An aseptic gauze dressing was applied to the treated area after each session. After four treatments, spaced one month apart, the tattoo had almost disappeared and the pruritus had improved (Fig. 1B), and after 10 treatments, the tattoo and the symptom were completely resolved (Fig. 1C).

Table 1 . Specific picosecond laser fluence used for each session. All sessions used a wavelength of 532 nm and a 4 mm spot size

Number of session	Fluence (J/cm2)
1	0.8
2	1.0
3	1.0
4	1.0
5	1.0
6	1.6
7	1.6
8	1.6
9	1.6
10	1.6

The irritating potential of red pigment may be linked to its origin. Historically, red ink was primarily composed of metals, including highly toxic mercury derivatives. Although modern red ink is now typically made from skin-friendly organic compounds such as azo dyes and quinacridone, it still carries a risk of triggering delayed hypersensitivity reactions. In addition, red pigment may be contaminated with various chemicals, toxins, pathogens, and other allergens, all of which can contribute to allergic complications [2,3]. It is believed that delayed hypersensitivity reactions may be triggered by the long-term metabolism of the ink or the interaction of an ink antigen with a carrier protein in the dermis [3]. However, since the specific allergen remains unidentified, the exact pathophysiology is still not fully understood [2-4].

The clinical presentation in this case suggests a consistent allergic reaction to the red tattoo dye. The patient exhibited classic symptoms, including persistent erythema, pruritus, and localized swelling, particularly in areas where red ink was present [1-4]. In rare cases, systemic reactions can occur, usually manifesting as widespread dermatotic eruptions, scaling, erythema, and papules over extensive areas of the body [3].

Topical or intralesional corticosteroids are used as first-line therapy for tattoo allergic reactions, but their effectiveness varies and is usually temporary or insufficient [4]. Complete removal of the culprit pigment is essential to achieve full remission of symptoms [3,4]. Conventional surgical excision can fully remove dermal tattoo pigments, but it is only favorable for certain anatomical locations and scarring is inevitable [4]. Dermabrasion or dermatome shaving may provide removal of reactive tissue and symptom relief, but these methods are limited to superficial pigment removal. Deeper shaving may result in prolongation of healing time and scarring [3].

Today, lasers have remained as the treatment of choice in tattoo removal based on the principle of selective photothermolysis―when a chromophore is heated for a time shorter than its thermal relaxation time, the destruction of the chromophore occurs without harming the surrounding tissue [5,6]. Nanosecond (10^-9 seconds) Q-switched (QS) Nd:YAG lasers have been widely used to remove tattoos, but recent studies have shown that picosecond (10^-12 seconds) lasers have demonstrated superior efficacy in tattoo removal, especially difficult-to-remove pigments like red [5]. The picosecond laser operates at shorter pulse duration, which allows for more efficient and precise pigment fragmentation with reduced adverse effects [5,6].

The QS Nd:YAG laser can also be used to treat allergic reactions of tattoos by selectively eliminating offending pigments [1,7]. However, a challenge in treating allergic reactions to red tattoo dye lies in removing the pigment without exacerbating the inflammatory response. An immune reaction may worsen during the laser treatment due to the photomechanical breakdown of the tattoo pigments [1,8]. Therefore, combination treatments with various local and systemic immunosuppressive therapies have already been attempted [1,7,8]. Antony and Harland [7] successfully used a 532 nm QS Nd:YAG laser combined with topical corticosteroids to remove refractory red tattoos in seven patients. van der Bent and van Doorn [1] treated a delayed allergic reaction to a red cosmetic tattoo with a 532 nm nanosecond QS Nd:YAG laser and oral methotrexate. Ashinoff et al. [8] used oral prednisolone and hydoxyzine before and after each QS laser session to prevent generalized urticarial eruptions in a patient with a multi-color tattoo. In this case, 20 mg/ml of intralesional TA injection was administered immediately after each session, and the patient did not report any allergic side effects throughout the treatment.

Combining ablative fractional laser resurfacing (AFR) with QS lasers can enhance tattoo lightening. The AFR enhances the transepidermal elimination of tattoo pigments through epidermal ablation, and increases inflammation and phagocytosis, accelerating pigment removal via lymphatic system [9-11]. Ibrahimi et al. [11] combined of erbium:YAG 2,940 nm AFR with a QS Nd:YAG laser device to treat allergic reaction to a red and black tattoo. At the 8-months follow-up after the fourth treatment, there was significant lightening of the patient’s tattoo along with symptom relief [11]. In this case, we also used combination laser therapy and successfully achieved remission of the patient’s symptoms. AFR may also increase topical drug delivery through ablated tissue columns [12]. However, since the tattoo ink is located at the dermal level [6], we injected corticosteroid intralesionally in order to more reliably prevent a secondary immune response caused by the destruction of the chromophore.

Unlike previous studies, this case utilized a fractional CO₂ laser in combination with a picosecond laser, rather than a nanosecond laser. Intralesional corticosteroid injections were also administered to prevent allergic reactions secondary to the laser treatment. As a result, the patient’s symptoms were effectively relieved, and the tattoo was removed without any complications. Further large-scale randomized controlled trials are needed to assess the efficacy of combining picosecond lasers with fractional CO₂ lasers in treating tattoo allergic reactions, as well as to compare this method with other laser modalities.

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Conceptualization: SJL. Data curation: SJL. Formal analysis: SJL, HL, JL. Investigation: JL, HL, SJL. Project administration: SJL, HKC. Supervision: SJL, HKC. Validation: SJL, HKC. Visualization: JL, HL, SJL. Writing–original draft: HL, JL. Writing–review & editing: all authors.

Hannah Lee has a personal connection with Sang Ju Lee. Hannah Lee contributed significantly to the drafting and revision of the original draft and has submitted supporting materials to the editorial office. Other than that, there is no potential conflict of interest relevant to this article.

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Contact the corresponding author for data availability.

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