DAPSONE
Updated: Oct 20
I don't hear from many patients who have used dapsone, although Dr. Richard Horowitz talks about it often. I have no experience using it myself, so I gathered the newest information from trusted sources to help you learn about it and talk it over with your doctor.
A quick-view graphic with the key points is at the bottom of this post.
WHAT DAPSONE IS
- Dapsone is a prescription antibiotic. It has long been used for leprosy and some skin conditions.
- In Lyme, it is used to go after "persisters," slow-growing forms of the bacteria that may help explain why symptoms keep coming back.
- Dr. Horowitz explains that it can reach the brain and nervous system, may help calm inflammation, and may also help with Babesia.
WHAT THE LAB RESEARCH FOUND
- A Tulane University study led by Dr. Monica Embers and funded by the Bay Area Lyme Foundation tested antibiotics in mice with persistent Lyme (2023).
- No single antibiotic cleared the infection. Three combinations that included dapsone did.
- This was a mouse study, so the researchers say it still needs to be studied in people.
TWO WAYS DOCTORS USE IT
DR. HOROWITZ'S DAPSONE COMBINATION THERAPY
- He usually starts with about 8 to 9 weeks of "double dose dapsone combination therapy" (DDDCT). Dapsone is raised slowly, and it is taken along with other antibiotics and methylene blue.
- This is followed by a short, stronger pulse called high dose dapsone combination therapy (HDDCT).
- For Bartonella, he often uses several 2-week pulses spaced about 6 to 8 weeks apart. He says at least four pulses are usually needed.
- He lays out the full week-by-week plan in Part 4 of his Bartonella series (linked in the sources below).
- Dr. Horowitz has retired from seeing patients one on one, but he still shares his work through his writing and talks.
DR. MARTY ROSS'S NORMAL-DOSE APPROACH
- Dr. Ross uses a lower, normal dose based on Dr. Horowitz's earlier research. He starts low, goes up slowly to as much as 100 mg a day, and combines it with other antibiotics.
- He may consider it for people with chronic Lyme or Bartonella who have not gotten better after a year or more of other treatment.
- He shares that about 30 percent of his patients can't tolerate it.
- He prefers this normal-dose approach over the double-dose and high-dose protocols.
WHAT THE PATIENT STUDIES SHOW
- 2020: In 40 patients treated with double dose dapsone combination therapy, 98 percent improved, and 45 percent stayed in remission for a year or longer.
- 2023: In 25 patients who also did high dose pulses, all improved. Patients with Bartonella did better with 6 to 7 day pulses than with 4 day pulses.
- 2024: A report of 3 patients with Lyme, Babesia and Bartonella found that Bartonella needed one or more 6 day pulses to reach remission.
- These are small studies from Dr. Horowitz's own clinic, without a comparison group. He has applied for funding for a larger placebo-controlled trial.
PLEASE BE CAREFUL
- Dapsone is a prescription treatment that needs close care from your doctor.
- A G6PD blood test must be checked first. People low in this enzyme can have their red blood cells break down.
- Dapsone can lower folate and cause anemia, so doctors add special forms of folate and check blood counts often.
- It can raise methemoglobin, which affects how blood carries oxygen. Dr. Horowitz notes that home pulse oximeters can't give accurate readings on his protocol, so blood tests are needed instead.
- On his protocol, he also advises avoiding drugs that can raise methemoglobin, like Tylenol and certain anesthetics.
- Strong herx reactions can happen, which is one reason doctors start low and go slow.
- Talk with your doctor before adding anything.
RELATED POSTS
Methylene Blue:
Antibiotics: Why Using Only One Is Not Recommended in Chronic Lyme:
https://www.riseabovelyme.com/post/antibiotics-why-using-only-one-is-not-recommended-in-chronic-lyme
Pulsing Antibiotics:
Persistent Lyme:
Cyst Forms of Lyme:
Biofilms:
Biofilm Solutions:
Bartonella:
Babesia:
Herx Solutions:
Herx vs. Flare:
Anemia in Lyme and Co-Infections:
Methylation and MTHFR:
Lyme Protocols:
One Treatment Does Not Fit All:
Chronic Lyme:
SOURCES
LymeDisease.org, Dr. Richard Horowitz, Medical Detective: The Complex Role of Bartonella in Chronic Illness, Part 1 of 5 (2025):
LymeDisease.org, Dr. Richard Horowitz, Medical Detective: Establishing the Diagnosis of Bartonella, Part 2 of 5 (2025):
LymeDisease.org, Dr. Richard Horowitz, Medical Detective: Effective Treatments for Bartonella Infections, Part 3 of 5 (2025):
LymeDisease.org, Dr. Richard Horowitz, Medical Detective: Protocol for Treating Bartonella, Part 4 of 5, with the week-by-week layout (2025):
LymeDisease.org, Dr. Richard Horowitz, Medical Detective: 2-Week Pulses of Antibiotics for Chronic Bartonellosis, Part 5 of 5 (2025):
ILADEF (ILADS Educational Foundation), Dr. Richard Horowitz, How Does Dapsone Work? (2024):
LymeDisease.org, Combo Antibiotics Shown to Eradicate Lyme Disease in Mice, Tulane research led by Dr. Monica Embers (2023):
Horowitz, Fallon, Freeman. Combining Double-Dose and High-Dose Pulsed Dapsone Combination Therapy for Chronic Lyme Disease/PTLDS and Co-Infections, Including Bartonella: A Report of 3 Cases. Microorganisms (2024):
Horowitz, Fallon, Freeman. Comparison of the Efficacy of Longer versus Shorter Pulsed High Dose Dapsone Combination Therapy. Microorganisms (2023):
Horowitz, Freeman. Efficacy of Double-Dose Dapsone Combination Therapy in the Treatment of Chronic Lyme Disease/PTLDS: A Report of Three Cases and Retrospective Chart Review. Antibiotics (2020):
Dr. Marty Ross, Dapsone for Lyme Persisters (updated 2026)
LymeDisease.org, Lessons from Treating 13,000 Lyme Survivors, with Dr. Richard Horowitz (2026):
Disclaimer: Rise Above Lyme makes no claims about any possible benefit of using any product mentioned within this site. Always consult with your doctor before adding anything. The information shared is based on personal experience, years of accumulated researched resources from Lyme Literate doctors and polls conducted within Lyme groups from actual patient experience using these solution ideas.
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