From the Guidelines
Lyme rash and cellulitis are distinct skin conditions that require different approaches to diagnosis and treatment, with Lyme rash typically presenting as a circular, expanding red area and cellulitis as a spreading area of red, swollen skin that feels hot and painful to touch. To distinguish between the two, it's essential to consider the characteristics of each condition. Lyme rash, also known as erythema migrans, usually develops 3-30 days after a tick bite and is rarely painful or itchy, while cellulitis develops rapidly and is often accompanied by fever, chills, and swelling. Some key differences between the two conditions include:
- Appearance: Lyme rash often has a "bull's-eye" pattern, while cellulitis has poorly defined borders that may expand quickly.
- Pain: Lyme rash is rarely painful, while cellulitis is often tender and painful to touch.
- Fever: Cellulitis is often accompanied by fever, chills, and swelling, while Lyme rash is not.
- Cause: Lyme rash is caused by Borrelia burgdorferi bacteria transmitted by tick bites, while cellulitis is caused by common bacteria like Streptococcus or Staphylococcus entering through breaks in the skin. According to the practice guidelines for the diagnosis and management of skin and soft tissue infections, typical cases of cellulitis without systemic signs of infection should receive an antimicrobial agent that is active against streptococci 1. In contrast, Lyme disease requires antibiotic treatment, typically doxycycline, amoxicillin, or cefuroxime for 10-14 days. It's crucial to seek medical attention promptly if you notice a rash with these characteristics, as both conditions require antibiotic treatment, but with different medications and durations. The recommended duration of antimicrobial therapy for cellulitis is 5 days, but treatment should be extended if the infection has not improved within this time period 1. In severely compromised patients, broad-spectrum antimicrobial coverage may be considered 1. Elevation of the affected area and treatment of predisposing factors, such as edema or underlying cutaneous disorders, are also recommended 1. Outpatient therapy is recommended for patients who do not have systemic signs of infection, altered mental status, or hemodynamic instability 1. Hospitalization is recommended if there is concern for a deeper or necrotizing infection, for patients with poor adherence to therapy, for infection in a severely immunocompromised patient, or if there are systemic signs of infection 1.
From the Research
Distinguishing between Lyme Rash and Cellulitis
- Lyme rash, also known as erythema migrans, is a characteristic symptom of Lyme disease, presenting as a circular, expanding rash at the site of the tick bite 2, 3.
- Cellulitis, on the other hand, is a bacterial skin infection that can cause redness, swelling, and warmth of the skin, often accompanied by fever and chills.
- The key differences between Lyme rash and cellulitis are:
- Appearance: Lyme rash typically appears as a single, circular lesion with a clear center, while cellulitis often presents as a more diffuse, spreading area of redness and swelling.
- Location: Lyme rash usually occurs at the site of the tick bite, while cellulitis can occur anywhere on the body.
- Symptoms: Lyme rash is often accompanied by flu-like symptoms such as fever, headache, and fatigue, while cellulitis is typically characterized by pain, swelling, and warmth of the affected area.
- Diagnosis of Lyme disease is usually made clinically, based on the presence of erythema migrans and other symptoms, and can be confirmed by laboratory tests 2, 4.
- Treatment of Lyme disease typically involves antibiotics such as doxycycline or amoxicillin, while cellulitis is usually treated with antibiotics such as cefalexin or clindamycin 2, 5, 6.