Evidence-Based Guide

Antibiotics for a Cat Scratch: What the Evidence Says

Why most scratches need only washing, how an infected scratch differs from cat scratch disease, what IDSA, the CDC and AFP each say about azithromycin, and when a swollen lymph node needs an in-person exam.

Medically reviewed by Parth Bhavsar, MD
Published: Nov 2026 · Last reviewed: Nov 2026
9 min read

Do you need antibiotics for a cat scratch?

Usually not. A shallow scratch washed promptly with soap and water typically heals on its own. A scratch that turns red, warm, swollen or pus-filled in the first few days is a skin infection, and a deep or puncture-like wound is often treated with an agent active against both aerobic and anaerobic bacteria, such as amoxicillin-clavulanate (IDSA 2014). Cat scratch disease is different: tender lymph nodes 1 to 3 weeks after exposure, caused by Bartonella henselae (CDC). IDSA recommends azithromycin for it; the CDC says antibiotics are sometimes recommended for otherwise healthy patients and are required for immunocompromised patients. In the one randomized trial, azithromycin shrank nodes faster in the first 30 days, with no difference afterward (Bass et al., 1998). A swollen lymph node needs an in-person exam. Red streaks, fever with spreading redness, or a scratch over a finger joint with pain on movement need in-person care now.
Medically reviewed by Parth Bhavsar, MD. Updated November 3, 2026.

Key Takeaways

  • A scratch that looks infected in the first few days is a skin infection, not cat scratch disease.
  • Cat scratch disease shows up later, as tender lymph nodes 1 to 3 weeks after the scratch. It usually resolves on its own, and an in-person exam is the right way to evaluate a swollen node.[1]
  • Professional guidance differs on antibiotics for cat scratch disease: IDSA recommends azithromycin; the CDC says antibiotics are "sometimes recommended" for otherwise healthy patients and are required for immunocompromised patients.[4][2]
  • Red streaks, fever with spreading redness, a scratch over a finger joint with pain on movement, or eye symptoms need in-person care now.

Do you need antibiotics for a cat scratch?

Usually not. A shallow scratch that is washed promptly with soap and water typically heals on its own. Two different problems can follow a scratch, and they are handled differently:

  • A skin infection of the scratch itself. Redness, warmth, swelling or pus around the scratch within the first few days.
  • Cat scratch disease. Enlarged, tender lymph nodes 1 to 3 weeks after exposure to a cat, sometimes with a papule or pustule at the scratch site and a low-grade fever.[1] It is caused by the bacterium Bartonella henselae.

Infected scratch or cat scratch disease?

Feature Skin infection of the scratch Cat scratch disease (Bartonella)
When it starts Usually within the first few days Lymph nodes enlarge 1 to 3 weeks after exposure[1]
Where Around the scratch Lymph nodes upstream of the scratch (armpit, elbow, neck, groin); a papule or pustule may sit at the scratch site
What it looks like Redness, warmth, swelling; pus suggests an abscess Enlarged, tender node; low-grade fever possible
Usual course Mild redness may settle with wound care; spreading infection needs treatment Usually self-limited; node swelling typically lasts 2 to 8 weeks and can persist for months[5]

How common is cat scratch disease?

An analysis of national insurance claims estimated about 12,000 outpatient diagnoses and about 500 hospitalizations for cat scratch disease each year in the United States among people under 65, with the highest rates in the South (6.4 per 100,000) and in children aged 5 to 9.[7] The bacteria spread when a scratch is contaminated with flea feces, and kittens carry the highest risk.[3]

When a scratch wound itself is infected

There are no clinical trials specific to infected cat scratches. A mildly red, warm scratch without pus behaves like a mild skin infection (nonpurulent cellulitis). Pus or a fluctuant lump suggests an abscess, which may need drainage in person.

When a cat-related wound is deep or behaves like a puncture, physicians often use the coverage IDSA recommends for infected animal bites: an agent active against both aerobic and anaerobic bacteria, such as amoxicillin-clavulanate (IDSA 2014, recommendation 42).[4] Pasteurella species were found in 75% of infected cat bites in a multicenter emergency department study.[8]

Cat scratch disease: what the guidance says about antibiotics

The major sources do not say the same thing, so here is each in its own words:

  • IDSA (2014 skin and soft tissue infection guideline, recommendation 47): "Azithromycin is recommended for cat scratch disease (strong, moderate)," at 500 mg on day 1 and 250 mg for 4 more days for patients over 45 kg.[4]
  • CDC (clinical overview, updated March 23, 2026): cat scratch disease is "usually self-limited but antibiotic treatment may reduce symptom duration"; antibiotics are "sometimes recommended" for otherwise healthy patients depending on severity and preference, and "CSD requires antibiotic treatment if the patient is immunocompromised."[2]
  • American Family Physician review: "Most cases of cat-scratch disease are self-limited and do not require antibiotic therapy" (evidence rating B); azithromycin "appears to be effective at reducing the duration of lymphadenopathy" (B).[5]

The evidence behind azithromycin is one small randomized trial. In 29 patients, 7 of 14 given azithromycin reached an 80% reduction in lymph node volume within 30 days, compared with 1 of 15 given placebo; after 30 days the groups did not differ.[6]

Disseminated disease (eye, liver, spleen, bone, brain or heart valve) is rare and is managed with an infectious disease specialist.

Why a swollen lymph node needs an in-person exam

A tender node after a cat scratch is most often cat scratch disease, but other causes of a single enlarged node, including lymphoma, can look similar. In a prospective German study of 721 patients with unexplained masses in the head and neck, cat scratch disease was the cause in 13.7%; the rest had other causes.[10] Evaluation involves feeling the node, and the AFP review calls serology (Bartonella antibody testing) "the best initial test." The same review advises physicians to follow up patients with a single enlarged node "even those with confirmed CSD," and notes biopsy "is appropriate in patients whose lymph nodes fail to involute."[5]

Features that call for prompt in-person evaluation, from a 2025 AFP review of lymphadenopathy:[9]

  • A node larger than 2 cm, hard, or matted or fixed to surrounding tissue
  • A node that persists beyond four weeks or comes with fever, night sweats or unintentional weight loss
  • A node above the collarbone (supraclavicular) or at the inner elbow (epitrochlear)
  • Enlarged nodes in several areas of the body at once

The CDC adds that draining a node with a needle is generally not recommended except to relieve severe pain and swelling or when the diagnosis is unclear.[2]

When to get in-person or emergency care

Go to an emergency department or urgent care in person for:

  • Red streaks spreading from the scratch, or redness spreading quickly
  • Fever or chills with a red, painful scratch
  • A scratch or puncture over a finger, hand joint or knuckle with swelling or pain when you move the finger
  • Redness on the face, around the eye, or on the neck
  • Pus, or a soft swollen lump that may need drainage
  • Blurred vision, or eye redness with a swollen node in front of the ear
  • A weakened immune system (for example, chemotherapy, advanced HIV, organ transplant, long-term steroids) and any sign of infection
  • A scratch from a stray or unfamiliar cat acting strangely: contact your local health department about rabies risk, as IDSA recommends consulting local health officials (recommendation 41)[4]

Tetanus: for people with 3 or more prior tetanus doses, the CDC advises a Tdap or Td dose for a clean, minor wound if the last dose was more than 10 years ago, and for any other wound, such as a puncture or a wound contaminated with saliva or dirt, if it was more than 5 years ago.[11] A deep scratch usually falls in the second group.

Prevention

From the CDC:[1]

  • Avoid scratches, bites and licks from cats, especially kittens and stray cats
  • Wash hands after handling cats, and wash any scratch with soap and water
  • Ask a veterinarian about flea prevention, and never use permethrin on cats
  • Keep cats indoors and away from strays

Frequently Asked Questions

Most cat scratches heal with washing and time. Antibiotics are considered when the scratch shows signs of infection, and sometimes for cat scratch disease. People with a weakened immune system who develop cat scratch disease need treatment, per the CDC.

Azithromycin is the antibiotic IDSA recommends and the only one with randomized trial evidence. In a 29-patient trial, a 5-day course shrank swollen lymph nodes faster in the first month, with no difference after 30 days. The CDC and the American Family Physician review note that many cases resolve without antibiotics.

Enlarged, tender lymph nodes usually appear 1 to 3 weeks after exposure to a cat, according to the CDC. A papule or pustule may appear at the scratch site.

Warning signs in the first few days are redness that spreads, warmth, swelling, pus, increasing pain, red streaks or fever. Red streaks or fever with a red scratch need in-person care now.

Yes. Cat bites are deep punctures with a high infection risk. Scratches are usually shallower. Our cat bite guide covers bites.

Typically 2 to 8 weeks, and sometimes several months (Klotz et al., 2011). A node that does not shrink, keeps growing, or comes with night sweats or weight loss needs an in-person exam.

A lymph node needs to be examined by hand, and testing usually starts with a blood test for Bartonella antibodies. That evaluation is best done in person with a primary care physician.

If the cat is a stray, unfamiliar or acting strangely, contact your local health department. IDSA recommends consulting local health officials on whether rabies vaccination is needed.

About this guide

TeleDirectMD sees adults by video for mild skin infections (see cellulitis) and for recent cat bites without signs of infection (cat bite). Cat scratch disease and swollen lymph nodes are evaluated in person. This guide is general education, not a diagnosis. For an emergency, call 911. Questions: contact@teledirectmd.com

References

  1. Centers for Disease Control and Prevention. About Cat Scratch Disease. Updated September 11, 2026. https://www.cdc.gov/bartonella/about/about-cat-scratch-disease.html
  2. Centers for Disease Control and Prevention. Clinical Overview of Cat Scratch Disease. Updated March 23, 2026. https://www.cdc.gov/bartonella/hcp/clinical-overview/cat-scratch-disease.html
  3. Centers for Disease Control and Prevention. Bartonella henselae: Key points. Updated March 23, 2026. https://www.cdc.gov/bartonella/hcp/bartonella-henselae
  4. Stevens DL, Bisno AL, Chambers HF, et al. Practice Guidelines for the Diagnosis and Management of Skin and Soft Tissue Infections: 2014 Update by the Infectious Diseases Society of America. Clin Infect Dis. 2014;59(2):e10-e52. https://doi.org/10.1093/cid/ciu444
  5. Klotz SA, Ianas V, Elliott SP. Cat-scratch Disease. Am Fam Physician. 2011;83(2):152-155. PMID 21243990. Review (secondary source). https://www.aafp.org/pubs/afp/issues/2011/0115/p152.html
  6. Bass JW, Freitas BC, Freitas AD, et al. Prospective randomized double blind placebo-controlled evaluation of azithromycin for treatment of cat-scratch disease. Pediatr Infect Dis J. 1998;17(6):447-452. https://doi.org/10.1097/00006454-199806000-00002
  7. Nelson CA, Saha S, Mead PS. Cat-Scratch Disease in the United States, 2005-2013. Emerg Infect Dis. 2016;22(10):1741-1746. https://doi.org/10.3201/eid2210.160115
  8. Talan DA, Citron DM, Abrahamian FM, Moran GJ, Goldstein EJ. Bacteriologic analysis of infected dog and cat bites. N Engl J Med. 1999;340(2):85-92. https://doi.org/10.1056/NEJM199901143400202
  9. Falk N, Joseph R, Dieujuste M. Lymphadenopathy: Evaluation and Differential Diagnosis. Am Fam Physician. 2025;112(3):286-293. PMID 40961306. Review (secondary source). https://www.aafp.org/afp/2025/0900/lymphadenopathy
  10. Ridder GJ, Boedeker CC, Technau-Ihling K, Sander A. Cat-scratch disease: Otolaryngologic manifestations and management. Otolaryngol Head Neck Surg. 2005;132(3):353-358. https://doi.org/10.1016/j.otohns.2004.09.019
  11. Centers for Disease Control and Prevention. Adult Immunization Schedule Notes: Tdap and Td, wound management. https://www.cdc.gov/vaccines/hcp/imz-schedules/adult-notes.html

About the Author

Parth Bhavsar, MD

Parth Bhavsar, MD is a board-certified family medicine physician. This guide was written to reflect the 2014 IDSA skin and soft tissue infection guideline, current CDC guidance on cat scratch disease, and the primary studies cited above.

Medically reviewed by Parth Bhavsar, MD. Published Nov 2026.