At the turn of the twentieth century, few inventors contributed more profoundly to the practical use of electricity than Nikola Tesla. Among his lesser-known innovations was a form of high-frequency electrical therapy that would inspire decades of medical and cosmetic devices, collectively called the violet ray. Once endorsed by physicians, osteopaths, and healers such as Edgar Cayce, these instruments offered a gentle electrical stimulation that many believed encouraged circulation, nerve health, and cellular vitality.
Although violet ray machines were widely sold and used between 1900 and 1950, by mid-century they virtually disappeared from medical offices and catalogs. Their decline was not a matter of conspiracy, but rather of changing medical standards, new pharmaceutical options, and increasing regulation of therapeutic claims. Yet, even today, the underlying principles of Tesla’s high-frequency field therapy continue to inform modern technologies in physiotherapy, diathermy, and light-based medicine.
Tesla’s early experiments with high-frequency, high-voltage, low-current electricity (beginning in the 1890s) revealed that such currents could pass through the human body harmlessly while producing warmth and light. In his 1891 lecture before the American Institute of Electrical Engineers, he demonstrated that “electricity could stimulate the body’s tissues and nerves without destructive heating.”
These discoveries led Tesla to patent the Tesla coil, a resonant transformer capable of generating high-frequency oscillations. He foresaw not only wireless communication but also medical applications for these frequencies. He wrote of their potential “to stimulate life functions, accelerate circulation, and aid in the restoration of vitality.”
By the early 1900s, numerous manufacturers, inspired by Tesla’s coil design, produced portable high-frequency generators. These devices, known as violet rays, typically included a small transformer, a hand-held wand, and interchangeable glass electrodes filled with noble gases such as argon or neon. When activated, the electrode emitted a soft violet glow and a gentle warmth.
When applied to the skin, the violet ray created a mild diathermic effect, warming tissues, expanding small blood vessels, and increasing local circulation. Early practitioners also observed that the device generated trace amounts of ozone and ultraviolet light, which had modest antibacterial and skin-cleansing effects.
In an age before antibiotics, these effects were viewed as nothing short of revolutionary. Doctors and osteopaths used violet rays for:
- Arthritis and rheumatism
- Neuralgia and poor circulation
- Skin infections and acne
- Hair and scalp stimulation
- Chronic fatigue and depression
In the 1920s, the American Electro-Therapeutic Association listed high-frequency therapy as an accepted physical-medicine modality.
The renowned medical intuitive Edgar Cayce recommended the violet ray in nearly 900 of his health readings, citing its ability to balance the body’s “electrical energy” and stimulate nerve coordination. His readings described the human body as a “living electromagnetic system,” long before modern bioelectric medicine confirmed that cells and tissues generate measurable electrical potentials.
For instance, Cayce advised one patient with poor circulation to use the violet ray over the legs each evening, predicting improved physical and mental vitality within weeks. For arthritis, he recommended applying it along the spine and affected joints to relax muscles, oxygenate tissues, and relieve pain.
While Cayce’s explanations employed metaphysical language, modern physiology recognizes that electrical and magnetic fields do influence cell function, membrane permeability, and microcirculation, a concept now explored in pulsed electromagnetic field (PEMF) therapy and other regulated modalities.
During the first half of the 20th century, violet ray units were as common in clinics as stethoscopes. Medical supply catalogs sold them nationwide; advertisements appeared in Popular Mechanics and Ladies’ Home Journal.
Physicians used large floor models for physical therapy, while portable hand-held versions were marketed for home wellness. Some beauticians incorporated violet ray treatments to rejuvenate the skin and stimulate hair follicles, practices that, remarkably, still survive in modern spas and dermatology offices under the label “high-frequency facial.”
Clinical reports from the 1920s–30s noted improved wound healing and relief of pain when the devices were properly applied. The mechanism, now well understood, is mild diathermy, which increases local blood flow and accelerates tissue metabolism.
By the late 1940s, medical technology was rapidly evolving. The Food and Drug Administration (FDA), newly empowered under post-Depression legislation, required all therapeutic devices to substantiate their claims with clinical data. Many violet ray manufacturers, especially small firms, could not meet those new evidentiary standards.
In 1951, the FDA brought legal action against Master Electric Company of Marion, Indiana, one of the last remaining producers. The agency seized devices and charged the company with misbranding under the Federal Food, Drug, and Cosmetic Act, not because the devices were dangerous, but because their advertised claims of curing dozens of ailments lacked proof.
The court agreed, and the ruling effectively ended U.S. production of violet ray medical instruments. However, the technology itself was not banned for safety reasons. Rather, it was reclassified as non-medical. Manufacturers could no longer promote it for therapeutic use without clinical trials, which were financially unfeasible for small firms.
Although commercial production ended, the underlying science continued to evolve. Tesla’s high-frequency principles live on in several contemporary technologies:
| Modern Device/Field | Concept Derived from Tesla’s High-Frequency Work |
| Shortwave and microwave diathermy | Therapeutic deep-tissue heating for circulation and pain relief |
| Electrosurgery units | High-frequency current used for cutting and coagulating tissue |
| Pulsed electromagnetic field (PEMF) therapy | Low-frequency electromagnetic pulses to promote bone and tissue healing |
| Ultraviolet sterilization lamps | Ionized gas discharge similar to violet ray’s antibacterial effect |
| High-frequency cosmetic wands | Modern descendants of the violet ray, used safely for acne and scalp care |
Each of these modern devices reflects Tesla’s original insight: that precisely controlled electrical frequencies could influence biological function without harm.
The story of the violet ray is not one of suppression, but of evolution. Tesla’s technology emerged at a time when medicine was still discovering how electricity interacted with life. It inspired a generation of electrotherapists, offered comfort to millions, and paved the way for legitimate medical and cosmetic uses that endure today.
While the FDA’s stricter standards were intended to “protect consumers,” they also marked the end of an era when inventors could freely merge science and healing innovation. Modern bioelectronic medicine, from transcranial stimulators to magnetic resonance therapy, continues to validate Tesla’s core belief:
“If you want to find the secrets of the universe, think in terms of energy, frequency, and vibration.” ~ Nikola Tesla
References
- Tesla, N. Experiments with Alternate Currents of High Potential and High Frequency (Lecture, 1891).
- Museum of Disability History, “I Sing the Body Electric,” 2019.
- American Electro-Therapeutic Association, Proceedings, 1918.
- Edgar Cayce Readings, Association for Research and Enlightenment (A.R.E.), Case 137-1.
- Markov, M. S. “Pulsed Electromagnetic Field Therapy: History, State of the Art, and Future.” Environmental Health and Preventive Medicine (2007).
- Glidewell Dental, “Shocking Dentistry: Modern Clinical Applications for an Old Device,” Chairside Magazine, Vol. 4, Issue 4, 2010.
- McGarey, W. A. M.D., A.R.E. Clinic Studies on Violet Ray Applications, Phoenix, AZ (unpublished notes, cited in Venture Inward, 1989).
- U.S. v. One Device, Labeled in Part ‘Master Violet Ray’, U.S. District Court, Marion, Indiana, 1951.
- Carlson, W. B. Tesla: Inventor of the Electrical Age. Princeton University Press, 2013.