For decades, the “bullseye rash” has been the defining image of Lyme disease — a symbol found in medical textbooks, public health posters, and clinic checklists across America.

But a new study published in JAAD Reviews — the official dermatology journal of the American Academy of Dermatology — reveals that this long-standing belief has misled doctors for nearly 50 years, resulting in countless missed or delayed diagnoses.

The study, “Rethinking Erythema Migrans After 50 Years of Lyme Disease in the United States” (Salmen, Cook & Pierson, 2025), challenges the classic description of the Lyme disease rash — known as erythema migrans (EM) — and calls for a complete shift in how early Lyme is identified and treated.

🔍 What the JAAD Study Found

Researchers from the University of Vermont Health Network and Northeast Ohio Medical University reviewed decades of dermatologic data and Lyme case histories. Their findings revealed:

• 🩸 Erythema migrans (EM) — the hallmark rash of Lyme — appears in over 80% of cases, according to JAAD Reviews.

• ❌ The classic “bullseye” is rare. Most EM rashes are oval, uniform red patches that expand over days and align with skin tension lines.

• 🌿 About 1 in 5 patients develop multiple lesions, indicating early bacterial spread.

• ⚠️ On darker skin tones, EM may appear faint or subtle — a key reason why Lyme is often diagnosed later in Black and brown patients.

• 🎄 A “Christmas Tree” Rash Pattern – Researchers also described a striking visual pattern seen in some patients — a “Christmas tree” eruption. Several oval rashes can align along the body’s natural skin tension lines, mimicking the shape of a tree and reflecting early bacterial spread through the skin.

“We were told it couldn’t be Lyme without a bullseye — and we paid the price.”
— Lyme Patient, Tick Boot Camp Community

This study confirms what many chronic Lyme patients have long said: the medical system has been looking for the wrong rash.

🧬 Why This Matters for Lyme Patients

Lyme disease, caused by the bacterium Borrelia burgdorferi and spread through blacklegged (Ixodes) ticks, affects nearly half a million Americans each year.

When recognized early, Lyme can often be treated effectively with antibiotics. But when the early rash is missed or misidentified, the infection can spread, leading to:

• Chronic fatigue

• Neurological symptoms (“Lyme brain”)

• Joint pain and arthritis

• Cardiac complications

• Immune dysregulation and long-term illness

By redefining what erythema migrans truly looks like, this JAAD Reviews research could improve early detection — and prevent thousands of chronic Lyme cases every year.

⚠️ How the “Bullseye Myth” Took Hold

The bullseye image entered medical literature in the 1970s as a teaching shortcut.
Unfortunately, that simplification became a barrier to proper diagnosis. Many doctors still dismiss Lyme disease if a patient’s rash isn’t perfectly circular with a pale center.

This new study calls for an update to both medical education and public health awareness — especially for skin of color, where EM can look very different.

💡 What Patients and Clinicians Should Know

To improve early detection and reduce chronic illness, JAAD Reviews recommends:

✅ Evaluating any expanding red or oval rash after a tick bite — not just “bullseyes.”
✅ Recognizing that Lyme rashes vary by skin tone and location.
✅ Understanding that multiple rashes indicate early bacterial spread.
✅ Using clinical judgment, not outdated visuals, to diagnose and treat early Lyme.

🌎 The Bigger Message

This JAAD Reviews study is a turning point in Lyme research and advocacy.
It validates patient experiences, demands better medical training, and highlights the urgent need for inclusive diagnostic imagery across all skin types.

“Recognizing erythema migrans early could prevent years of chronic illness and suffering.”

For the chronic Lyme community, this is more than science — it’s long-overdue validation.

🎧 Learn More

To explore this study and what it means for the future of Lyme diagnosis, view the JAAD Pre-Proof (PDF) and tune in to the Tick Boot Camp Podcast, where we break down new research with top Lyme doctors, researchers, and survivors.