Dr. Mark Detweiler, MD
New Patients

Dr. Mark Detweiler, MD


Gastroenterology | Male

Londonderry Gastroenterology 1B Commons Dr Unit 9A Londonderry, NH 03053 Get Directions

Care Philosophy

I am a doctor who takes time to listen to your concerns, and includes you in making decisions abut your care. When possible I prefer to avoid antibiotics and other prescription medications as they the often have unwanted side effects. I also prefer to treat the root cause of a problem rather than bandage over the symptoms.


Dr. Mark Detweiler, MD is a gastroenterology doctor who practices in Londonderry, NH. He is 64 years old and has been practicing for 38 years.

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Dr. Detweiler's Experience

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Visiting Dr. Detweiler

Dr. Detweiler accepts 10 insurance carriers

Dr. Detweiler's Reviews

Likelihood of recommending Dr. Detweiler to family and friends
based on 16 total surveys (2 with reviews)
Dr. Detweiler's Performance
  • Trustworthiness
  • Explains condition(s) well
  • Answers Questions
  • Time well spent
Office & Staff Performance
  • Scheduling
  • Office environment
  • Staff friendliness
  • Average wait time
    10 to 15 minutes
Patient Reviews (2)
in Hudson, NH |
I am so impressed with Dr. D.Years of being dismissed by my sons pediatrician and telling me his symptoms were normal and no big deal left me frustrated; I knew something was not right so I went for another opinion w Dr.D. At the 1st visit he knew something was amiss, we did various tests and found the problem.He explained things to my son so he could understand and how HE Had to take control of his issue and it made a huge impact.Dr D sees both my sons and I could not be more grateful.
Londonderry, NH |
Scary! Received a summary of visit a few days after my appointment. Confused me with another patient. Listed symptoms I never had, but never mentioned the symptoms I did have. Wouldn't return my call. He Got indignant when I told receptionist- no nurses - what happened. Said I could make an additional appointment to get my symptoms right . Guess his mistakes are my fault?
This patient was not confused with anyone else. Symptoms are recordeed as given to me or as recorded in records released to me from other providers. My average preparation time for new patients is 45 minutes and includes careful review of the patient's own report of their issues. If this patient's assertions are true, I would have violated all of my operating practices. I do not know what the real problem here is as I can not identify the patient. This is totally opposite to my other reviews.
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Dr. Detweiler's Care Philosophy

I am a doctor who takes time to listen to your concerns, and includes you in making decisions abut your care. When possible I prefer to avoid antibiotics and other prescription medications as they the often have unwanted side effects. I also prefer to treat the root cause of a problem rather than bandage over the symptoms.

Dr. Detweiler says...

What is unique about my treatment is that I combined the best of both evidence-based medicine and nutrition, along with the 3000-year-old tradition of using herbs as medicine.  I will use whatever set of tools are the least toxic and most appropriate for a given patient.  Statistical humans in a one on one doctor patient relationship are pretty much irrelevant.  Each individual treatment plan is fundamentally an experiment.  This goes for traditional physicians as well, but they do not recognize it.  Many FDA approved medications work on as few as 20 to 30% of patients.  Thus, when one is prescribed such medication.  It is basically an experiment to see if it works for you.  Similarly, the choice of an herbal or nutritional program will necessarily be an experiment.  I have 15 years of experience in the use of mixed medical paradigms and feel very comfortable with the biases that I've developed, but recognize that they are biases.  Most of my decisions are based on current cutting edge research in the immune system's response to the organisms that live in the intestines (the gut microbiome) and its response to what is eaten.  Therefore, I will analyze for these issues in many instances and use that as a guide to begin therapy.  If you have a serious autoimmune disease, such as ulcerative colitis or Crohn's disease.  I am not hesitant to use the most powerful therapy necessary, including anti-TNF alpha antibodies but rather than leave you on these forever once control is obtained, I will try and create a gut environment that allows de-escalation and hopefully removal of these very useful but toxic drugs.

Similarly, chronic reflux issues are many times related to poor gut motility and gut motility is often related to what lives in it and what you eat.  Therefore, looking at these factors may solve an issue where acid blockers have been necessary for many decades.  Western medicine is wonderful for acute injury and highly active inflammatory diseases but is of very little help in the maintenance of chronic disease. 

Lastly, I feel my role is more of a coach that a parent.  For your particular illness.  I will recommend the approach that appears to be best, but it will be up to the individual to carry that out.

Dr. Detweiler's experience matches your search based on the following criteria:

  •  Based on total number of patients treated over the last 12 months
  •  Specializes in Gastroenterology
  •  Board certified in Gastroenterology and Internal Medicine
  •  Malpractice claims in New Hampshire not available
  •  No sanctions found
  •  No board actions found

Awards & Recognition

  • Awards & Honors
    • Healthgrades Honor Roll
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  • Media & Publications

    Dr. Detweiler has no media or publications listed.

Background Check

  • n/a
    Malpractice Claims not available

    Healthgrades does not collect malpractice information for New Hampshire.

    What is medical malpractice
  • 0

    No sanctions history found for the years that Healthgrades collects data.

    What is a sanction or disciplinary action
  • 0
    Board Actions

    No board actions found for the years that Healthgrades collects data.

    What are board actions

Board Certifications

Why It Matters: Dr. Detweiler's Board Certifications

Board certification should be one of your top considerations when choosing a doctor. Board certification is an official recognition given to doctors who have met specific requirements set by national medical specialty boards in the... More

  • Gastroenterology
  • Internal Medicine

Conditions Treated

  • Abdominal Disorders
  • Abdominal Pain
  • Abscess
  • Anemia
  • Autoimmune Diseases
  • Bacterial Infections of the Digestive Tract
  • Candida Albicans Fungus Allergy
  • Celiac Disease
  • Cirrhosis
  • Colitis
  • Colon Disorders
  • Constipation
  • Crohn's Disease
  • Diaphragmatic and-or Hiatal Hernia
  • Diarrhea
  • Diverticulitis, Intestinal
  • Diverticulosis, Intestinal
  • Duodenal Ulcer
  • Duodenitis
  • Dysphagia
  • Enteritis
  • Esophageal Achalasia and Cardiospasm
  • Esophageal Diseases
  • Esophageal Ulcer
  • Esophagitis
  • Fungal Infections
  • Gas-Bloat Syndrome
  • Gastric Ulcer
  • Gastritis
  • Gastroesophageal Reflux Disease (GERD)
  • Gastrointestinal Diseases
  • Gastrointestinal Malabsorption
  • Gastroparesis
  • Gluten Sensitivity
  • Heartburn
  • Hemochromatosis
  • Hemorrhoids
  • Hepatic Encephalopathy
  • Hepatitis
  • Hepatitis C
  • Indigestion
  • Inflammatory Bowel Disease
  • Invasive Candidiasis
  • Irritable Bowel Syndrome
  • Lactose Intolerance
  • Malnutrition
  • Nausea
  • Non-Alcoholic Fatty Liver Disease
  • Non-Neonatal Jaundice
  • Noninfectious Gastroenteritis and Colitis
  • Pancreatitis
  • Peptic Ulcer
  • Pyloric Stenosis
  • Stomach Diseases
  • Stomach and Small Intestine Cancer
  • Ulcer
  • Ulcerative Colitis
  • Unexplained Weight Loss
  • Viral Hepatitis
  • Vomiting Disorders


  • Medical School
    Pennsylvania State University College Of Medicine

    Graduated in 1979

  • Internship Hospital
    University Vt Med Center Hospital

    Completed in 1980

  • Residency Hospital
    University Vt Med Center Hospital

    Completed in 1981

  • Fellowship Hospital
    University Utah Med Center

    Completed in 1984

  • Undergraduate School
    Lehigh University Bs Chemistry

    Graduated in 1975

Languages Spoken

  • English

Memberships &
Professional Affiliations

Dr. Detweiler does not have any memberships or affiliations listed. If you are Dr. Detweiler and would like to add memberships or affiliations, please update your free profile.


  • Gastroenterology
  • Applied Clinical Nutrition
  • Holistic Medicine

Procedures Performed

Dr. Detweiler does not have any procedures listed. If you are Dr. Detweiler and would like to add procedures you perform, please update your free profile.