Ullman was interviewed on the American Broadcasting Company program 20/20 in a segment about homeopathy (January 30, 2004). He claimed that homeopathic preparations of extremely high dilution, i.e. those likely to contain zero molecules of the original substance, are effective because, he said, "the water gets impregnated with the information or memory of the original substance." When asked to suggest a laboratory experiment that 20/20 could independently conduct as a way to test the legitimacy of homeopathy, Ullman recommended the Ennis experiment, a study that seemed to show that ultra-dilute solutions of histamine, diluted to the levels used in homeopathic remedies, could affect cells just as the controls did. The result of 20/20's experiment was negative; the homeopathic dilution failed to produce a measurable effect when compared to plain water. Ullman has claimed the test was flawed as it was not a direct replication (repetition) of Ennis' work. Homeopathic Educational Services - John Stossel and 20/20's Program on Homeopathy: Junk Science Creates Junk Journalism When TV Science Creates Science Fiction Homeopathic Educational Services - Articles - Media reports However, this experiment and one run by the BBC were ruled to be valid by independent experts commissioned by the BBC, and the BBC did not claim the study to be a repetition but a replication.

In an editorial in The Journal of the Federation of American Societies for Experimental Biology, editor-in-chief Gerald Weissmann criticized the scientific basis of homeopathy and included Dana Ullman in his criticism. Weissmann criticized Ullman for recommending, during the 2001 anthrax attacks in the USA, the use of the homeopathic preparation called Anthracinum to prevent infection. Ullman said he recommended Anthracinium for people who are at high risk of infection and who decline ciprofloxacin because of concerns over its side effects. While Ullman expressed concern about vendors "taking advantage of people wrapped up in the fear of the situation", he said "It would be irresponsible for us not to provide something that might be helpful." There is no evidence for the efficacy of Anthracinum, which is derived from nosodes gathered from infected pigs, and then diluted to "a point where no molecules of the disease product remain." In a right-of-reply letter, Ullman depicted Weissmann's editorial as an "unscientific critique" of homeopathy and cited five peer-reviewed studies. Weissmann responded: "Mr. Ullman is clearly a devotee of his art, and I respect his opinions. I’m afraid that I view Mr. Ullman’s references to the efficacy of homeopathy as modern versions of those Dr Holmes distrusted," and went on to quote from a well-known critique of homeopathy by Oliver Wendell Holmes, Sr.: "...such cases deserve very little confidence. Yet they may sound well enough, one at a time, to those who are not fully aware of the fallacies of medical evidence."

Criticism of medical doctors

Regarding the treatment of children with pharmaceutical drugs and homeopathic remedies, Ullman has accused doctors of "medical" child abuse, saying:

"It deeply saddens me that so many parents and doctors give powerful drugs to infants and children. They unknowingly are committing what I call 'medical child abuse.' Although these may be harsh words today, I believe that history will show them to be accurate."

Ullman published an article on a similar theme on his website, in which he says:

"The care that conventional physicians offer is often valuable, but powerful and multiple drugs are dispensed far too frequently by too many doctors without an effort to try safer, more natural therapies. This over-prescribing is a type of "medical child abuse" that is a sad state of affairs, especially since the average doctor doesn't even recognize it as a problem. It seems prudent to save the "bigger guns" of pharmacology for the more serious conditions that warrant their use. ... This kind of overprescribing is sometimes the result of inadequate knowledge of recent research. It also sometimes occurs because a doctor feels compelled to prescribe something for a sick child. Doctors often assume that the medicine, even if not certain to be effective, will at least have a beneficial placebo effect. However, considering the potential side effects from nearly every drug, it seems more prudent to consider more mild placebos or safer medicines, such as homeopathic remedies."

• Everybody's Guide to Homeopathic Medicines (with Stephen Cummings, MD), 1984, 2004. ISBN 0-87477-843-3.
• Discovering Homeopathy: Medicine for the 21st Century, 1991. ISBN 1-55643-108-2
• Homeopathic Medicines for Children and Infants, 1992. ISBN 0-87477-692-9
• The Consumer's Guide to Homeopathy, 1995. ISBN 0-87477-813-1
• The Steps to Healing: Wisdom from the Sages, the Rosemarys, & the Times, 1999. ISBN 1-56170-657-4.
• Essential Homeopathy, 2002. ISBN 1-57731-206-6
• The One-Minute (or so) Healer, 2004. ISBN 1-55643-494-4
• The Homeopathic Revolution: Why Famous People and Cultural Heroes Choose Homeopathy, October, 2007. ISBN 1-55643-671-0

Other writings

Ullman's letters and writings have appeared in The Western Journal of Medicine, Social Policy, Utne Reader, The Futurist, The Arthritis Foundation's Guide to Alternative Medicine, Atlanta: Arthritis Foundation, (J. Horstman) 1999 and The Reader's Digest Family Guide to Natural Medicine.