There are three formally recognised skin manifestations of Lyme borreliosis: erythema migrans (the early rash), borrelial lymphocytoma (a subacute lesion, less common), and acrodermatitis chronica atrophicans (ACA — a late-stage finding). Beyond these, Bartonella co-infection produces its own distinctive skin patterns, and chronic immune dysregulation can drive further non-specific skin changes.
Each of these has different timing, different appearance, and different clinical significance. Understanding what each looks like — and what it means — is important both for early recognition and for understanding why skin findings may appear months or years after the initial infection, and why a dermatology consultation alone may miss the underlying cause.
Erythema migrans — the early rash
Erythema migrans (EM) is the most reliable early sign of Lyme disease when it is present. It is caused by the immune system reacting to Borrelia burgdorferi as the bacteria migrate outward from the site of the tick bite. The rash expands gradually — typically over days — and is usually at least 5 cm in diameter by the time it is clinically recognisable.
The most important thing to understand about erythema migrans is that it does not usually look like a bull's-eye. The classic concentric-ring "target" appearance is seen in a minority of cases. The majority of EM rashes are uniform in colour across their entire surface — a solid oval or circular area of pink, red, or slightly purplish discolouration — without any ring-within-ring pattern. Many clinicians trained to look only for the bull's-eye pattern fail to identify these more common presentations.
The rash is typically warm to the touch and may have a slight raised edge. It is usually round or oval but can be irregular in shape. Colour ranges from pale pink to deep red, and can have a slightly bluish or purplish tint. The centre of the rash may appear clearer (producing the target pattern) or may be uniformly the same colour as the outer area. The rash may itch, burn, or be entirely without sensation. It is typically not painful.
The rash typically appears between 3 and 30 days after the tick bite, with most cases appearing in the first 7–14 days. It appears at or near the site of the bite — but ticks most commonly attach in concealed locations (behind the knee, in the groin, under the arm, in the hairline, behind the ear) where rashes can easily be missed entirely. If the tick was removed without noticing a rash, this does not mean no rash was present.
In some patients, multiple rashes appear at different locations on the body simultaneously. These secondary rashes are not at additional bite sites — they are the immune system responding to bacteria that have already disseminated through the bloodstream from the original infection site. Multiple EM rashes are a sign of early disseminated Lyme disease and indicate that the infection has already spread systemically. This requires more aggressive treatment than single early-stage EM.
Photograph the rash immediately, including a ruler or coin for scale. Show the photograph to a clinician as soon as possible — the rash may fade or change before an appointment. In many clinical guidelines, the presence of an EM rash consistent with Lyme disease is sufficient to begin antibiotic treatment without waiting for blood test confirmation (tests are particularly unreliable in early disease). Do not wait for test results if the rash is present.
When there is no rash
Up to 30% of people infected with Lyme disease never develop a visible rash, or the rash appears in a location that is never noticed. The absence of a rash cannot be used to rule out Lyme disease — and a clinician who does so is working from an incomplete understanding of the condition.
The absence of a rash is one of the most common reasons Lyme disease is not diagnosed at an early stage — and early diagnosis is when treatment is most effective and outcomes are best. A patient who does not see a rash and is told "you would know if you had Lyme, you'd have had a bull's-eye rash" may go undiagnosed for months or years while the infection disseminates.
Ticks are small — nymphal ticks, which account for the majority of Lyme transmissions, are roughly the size of a poppy seed. Many bites go unnoticed entirely. Even when a rash develops, it may appear in a location the person cannot easily see, may be mistaken for a spider bite or skin irritation, or may fade quickly. In people with darker skin, the rash may be more difficult to visualise against the surrounding skin colour.
The absence of a rash does not change the infection. When a patient presents with multi-system symptoms consistent with tick-borne illness — fatigue, joint pain, neurological symptoms, cognitive difficulty — the lack of a rash history should not remove Lyme disease from the differential. The diagnosis must be based on the full clinical picture, not on a single feature that is known to be absent in a significant proportion of cases.
Borrelial lymphocytoma
Borrelial lymphocytoma is a less common but distinctive skin manifestation of Lyme disease that appears in the subacute phase — weeks to months after infection, when the bacteria have partially disseminated but the late stage has not yet developed. It is most common in Europe and relatively rare in North America, likely due to differences in the Borrelia strains present in each region.
The lesion appears as a solitary, firm, blue-red nodule or plaque — most commonly on the earlobe (particularly in children), the nipple, or the scrotum. It looks somewhat like a blueberry or a raised bruise, and is usually not painful or itchy. It can easily be mistaken for a benign cyst, a swollen lymph node, or a minor skin growth.
Borrelial lymphocytoma is a sign of Borrelia infection that requires antibiotic treatment. It does not resolve spontaneously. Serology (blood testing for Lyme antibodies) is positive in approximately 90% of cases — more reliably than in early EM, where serology is frequently negative. If the lesion is identified correctly and treated appropriately, it typically resolves over weeks to months with antibiotics. If mistaken for a benign finding and left untreated, infection may progress to late-stage disease.
ACA — acrodermatitis chronica atrophicans
Acrodermatitis chronica atrophicans (ACA) is the most common skin manifestation of late-stage Lyme borreliosis. It is caused by persistent, active Borrelia infection in the skin and develops months to years after the initial infection — often in patients who were never diagnosed or who received inadequate treatment. It is most commonly associated with the Borrelia afzelii strain, which is the predominant strain in Europe, and is therefore seen predominantly in European patients. It is less common but not absent in North American populations.
ACA is chronically underdiagnosed. It is frequently mistaken for a vascular condition, a dermatological disorder unrelated to infection, or simply dismissed as age-related skin changes. Many patients carry it for years before anyone connects it to Lyme disease.
ACA begins with a reddish or bluish-red discolouration of the skin on the extremities — most typically the dorsum (back) of the hand, the ankle, the knee, or the elbow. The skin appears slightly swollen and has a dull, mottled colour. It is typically not painful, which is part of why it is so often ignored. The affected area feels warmer than the surrounding skin. Early ACA is treatable and the changes are reversible with appropriate antibiotic therapy.
If left untreated, ACA progresses to an atrophic phase in which the skin becomes progressively thinner and loses its normal tissue structure — sweat glands, hair follicles, and elastic fibres disappear. The result is skin described as resembling tissue paper or cigarette paper: translucent, fragile, easily torn, and prone to ulceration after minor trauma. The underlying veins become visible through the skin. This phase represents permanent structural damage, and while antibiotic treatment can stop further progression by eliminating the infection, the existing skin changes do not reverse in late atrophic ACA.
ACA frequently coexists with peripheral neuropathy (nerve damage in the affected limb), joint involvement, and sometimes neurological symptoms. These are not coincidental — they reflect the same late-stage Borrelia infection affecting multiple tissues in the same region. A significant number of patients with ACA also have neuroborreliosis. Serology is positive in essentially 100% of ACA cases, making it one of the most serologically reliable presentations of Lyme disease.
Diagnosis requires clinical recognition, serological testing, and typically histopathological confirmation (a skin biopsy interpreted in the context of Lyme disease). A dermatologist who is not familiar with ACA may not consider Lyme as the cause — asking for Lyme serology alongside any investigation of unexplained atrophic skin changes on the extremities is important. Treatment is extended antibiotics (typically four weeks or more of doxycycline or amoxicillin, depending on other systemic involvement). Earlier treatment produces better outcomes.
Bartonella skin patterns
Bartonella is one of the most common co-infections carried alongside Borrelia in tick populations, and it produces its own distinctive and diagnostically valuable skin patterns. These patterns are poorly known in mainstream medicine — many patients carry them for years without any clinician recognising their significance. Understanding what Bartonella skin changes look like is therefore of practical importance.
The most characteristic Bartonella skin finding is the appearance of linear, stretch-mark-like marks — often described as striae. Unlike the white or silver appearance of typical stretch marks from rapid growth or weight change, Bartonella striae are typically pink, red, or purple in colour, particularly when active. They most commonly appear on the torso, upper thighs, buttocks, and upper arms — locations not typically associated with growth-related stretch marks. They do not fade to the same colour and texture as ordinary striae over time.
Research by Dr. James Schaller documented biopsies of Bartonella-associated striae showing elevated bacterial load within the lesion tissue and disrupted vasculature — consistent with active Bartonella infection in the skin. A 2020 Canadian research paper published in PMC documented Bartonella striae coexisting with ACA in the same patient, visually distinguishable from each other and both present simultaneously as a pattern of co-infection. The parallel, streaky arrangement of the marks is described as a distinguishing characteristic of Bartonella skin involvement.
Patients and clinicians alike attribute these marks to weight change, growth, or skin stretching — particularly because they appear in locations associated with growth-related stretch marks. A young person with Bartonella striae on the thighs or torso will typically be told these are normal pubescent stretch marks, which closes the investigation before it begins. The distinguishing features — colour (pink/red/purple rather than white/silver), unusual location for growth-related marks, or appearance without any period of rapid weight or height change — are not widely taught.
Bartonella can also cause bacillary angiomatosis — vascular skin lesions most typically seen in immunocompromised patients — and non-specific erythematous (red) skin changes. Generalised skin flushing, unexplained rashes, or vascular-appearing marks without injury have been reported in Bartonella infection. Night sweats and hypersensitivity to touch (allodynia) are also associated with Bartonella and may accompany skin symptoms.
Other skin changes in tick-borne illness
Beyond the formally classified manifestations, chronic Lyme disease and co-infections can drive a range of additional skin changes — most of which reflect an active, dysregulated immune system rather than direct pathogen invasion of skin tissue.
Recurrent or unexplained hives — particularly when they appear and disappear without an obvious allergic trigger — can be a manifestation of MCAS (mast cell activation syndrome), which is increasingly recognised in Lyme patients. When hives appear alongside other systemic symptoms, an infectious or inflammatory driver should be considered.
Drenching night sweats — particularly when they are profuse enough to require changing bedding or clothing — are a characteristic feature of Babesia co-infection (a parasitic tick-borne illness). They can also occur in Lyme disease and Ehrlichia infection. Night sweats in the context of tick-borne illness are not a skin condition per se, but they are a skin-level symptom that is frequently the clue that leads to investigation of Babesia.
A retrospective study of European borreliosis patients found psoriatic-type changes in a proportion of cases — scaly, inflammatory skin changes that resembled psoriasis but appeared in the context of active systemic infection. Erythema nodosum (painful red nodules, typically on the shins) and granuloma annulare (ring-shaped skin lesions) have also been associated with tick-borne illness in published research. These are immune-mediated skin responses to systemic inflammation and are typically seen in the chronic phase.
Research on European borreliosis patients has documented a pattern of redness and irritation on the palms and soles — described as "borreliosis palms or soles" — as a marker for chronic infection when present in combination with other systemic symptoms. This is a less-known finding and requires more research, but its appearance in published clinical data warrants awareness.
What a dermatologist may miss — and why
Dermatologists are trained to identify and treat skin diseases. They are not typically trained to connect skin findings to systemic infectious disease. The result is that several of the most important Lyme-related skin patterns — ACA, Bartonella striae, lymphocytoma — may be examined by a dermatologist who identifies a skin condition without identifying its cause.
The discolouration and tissue thinning of late-stage ACA closely resembles vascular insufficiency, livedo reticularis, or age-related skin atrophy. Without the context of potential Lyme disease exposure and without the clinical index of suspicion that comes from training in infectious skin manifestations, a dermatologist may make a dermatological diagnosis that is accurate at the surface level but completely misses the underlying infection driving it.
Without knowing that Bartonella produces skin striae, no clinician — dermatologist or otherwise — will consider it as a cause. The marks look like stretch marks. They are assumed to be stretch marks. The conversation ends there, and an active co-infection goes unidentified.
If you have skin findings you believe may be related to tick-borne illness, bringing the clinical context to the appointment matters. Mention outdoor exposure, the timeline of appearance relative to any tick bites or illness onset, and any systemic symptoms that accompany the skin changes. Ask specifically whether Lyme disease or a co-infection could be responsible, and ask whether Lyme serology has been considered. A dermatologist who is unfamiliar with these patterns may not raise them independently.
How to document skin findings
Skin findings are transient. Rashes expand, fade, change colour, and disappear — sometimes within days of their most visible presentation. What you document in the moment may be the only record that exists when you need to make a clinical case weeks or months later. Documentation is not optional — it is part of managing your own care effectively.
Photograph every skin finding as soon as you notice it. Take multiple photographs from different distances and angles. Include a ruler, coin, or credit card for scale. Take photographs in good natural light where possible — artificial lighting can alter the colour significantly. Note the date and time in the file name or add it manually. Photograph the same finding over several days to document how it changes.
Alongside photographs, write down: the exact location on the body; when you first noticed it; whether you noticed a tick bite in the same area; any sensation (itching, burning, pain, warmth); and whether it appeared or worsened alongside other symptoms (fatigue, joint pain, fever). This contextual information transforms a photograph into a medical document.
If a rash or skin finding has faded or changed by the time of your appointment, show the photographs. State clearly when the photographs were taken and describe what you observed. Do not let the absence of a current visible finding lead to the topic being dismissed — the photograph is the finding, and it deserves to be discussed and recorded in your clinical notes.
A note on uncertainty
Not every skin change is a sign of tick-borne illness. Many rashes have ordinary dermatological explanations — contact dermatitis, insect bites, folliculitis, fungal infection — that have nothing to do with Lyme disease or co-infections.
The purpose of this page is not to encourage you to interpret every skin symptom as infectious. It is to ensure that when a skin finding genuinely is related to tick-borne illness, it is not automatically attributed to something else before the question has been properly asked. The critical question is always: does this fit the broader picture? A skin finding in isolation is one thing. A skin finding in the context of fatigue, joint pain, and neurological symptoms is something else entirely — and deserves investigation of the whole.
Healing mentality checkpoint
Skin symptoms are often dismissed as minor or cosmetic. In tick-borne illness, they are sometimes the most visible manifestation of a systemic process — the immune system expressing, on the surface, what is happening underneath.
You do not need to arrive at a clinical appointment with certainty. You need to arrive with documentation, a clear history, and the right questions. The rest is the clinician's job — your job is to give them the information they need to do it.
Read about healing mentality →Healing mentality checkpoint
Skin symptoms are often dismissed as minor or cosmetic. In tick-borne illness, they are sometimes the most visible manifestation of a systemic process — the immune system expressing, on the surface, what is happening underneath.
You do not need to arrive at a clinical appointment with certainty. You need to arrive with documentation, a clear history, and the right questions. The rest is the clinician's job — your job is to give them what they need to do it.
Read about healing mentality →The skin is telling a story
Skin symptoms are often dismissed as cosmetic concerns, minor irritations, or the effects of aging. In tick-borne illness, they are sometimes the most visible manifestation of a systemic process — the immune system expressing, on the surface, what is happening underneath. They deserve to be taken seriously and documented carefully.
You do not need to arrive at a clinical appointment with certainty. You need to arrive with documentation, a clear history, and the right questions. The rest is the clinician's job — your job is to give them the information they need to do it.
Read about the healing mentality →Sources & further reading
- Müllegger R. — Skin manifestations of Lyme borreliosis: diagnosis and management, PubMed, 2004
- Scott JD — Presentation of Acrodermatitis Chronica Atrophicans Rashes on Lyme Disease Patients in Canada, PMC, 2020
- DermNet NZ — Acrodermatitis Chronica Atrophicans (dermnetnz.org)
- Medscape — Acrodermatitis Chronica Atrophicans: Practice Essentials
- Medscape — Lyme Disease Clinical Presentation
- Galaxy Diagnostics — Vector-Borne Disease and Skin: Your First Layer of Defense
- Ćosić I et al. — Clinical Manifestations of European Borreliosis on the Skin, PMC, 2024
- Branda JA et al. — The Spectrum of Erythema Migrans in Early Lyme Disease, PMC, 2022
- Buhner S.H. — Healing Lyme, 2nd ed. (2015)
Last updated: March 2026