Finsen's Nobel-winning light therapy and its role in treating skin tuberculosis

The Hindu

10 hours ago

In 1903, Danish physician and scientist Niels Ryberg Finsen was awarded the Nobel Prize in Physiology or Medicine 'in recognition of his contribution to the treatment of diseases, especially lupus vulgaris, with concentrated light radiation.'
Lupus vulgaris, a skin form of tuberculosis, was once treated with ultraviolet light therapy. In the late 1800s, Finsen discovered that concentrated UV light beams could inhibit bacterial growth, and he successfully used this treatment on patients. Although light therapy was widely used for a time, it eventually gave way to antibiotics. His groundbreaking work marked one of the earliest uses of a physical force --light as a therapeutic tool, and laid the foundation for what we now call phototherapy.
Personal health struggles and research
Finsen's scientific journey was inseparable from his personal health struggles. Born on December 15, 1860, in Tórshavn, in the Faroe Islands, then a remote territory of the Danish Kingdom, Finsen grew up in a family of educators and administrators. As a child, he showed academic promise, but his health was often precarious. By early adulthood, he began showing signs of a debilitating illness, now believed to be Niemann–Pick disease, a rare genetic condition affecting lipid metabolism. The disease caused chronic fatigue, abdominal swelling, and progressive physical decline, eventually leaving him largely immobile.
Unable to pursue a traditional clinical career due to his worsening condition, Finsen turned toward research. His own body became, in part, a source of inspiration. He noticed that exposure to sunlight offered some temporary relief from his symptoms and became curious about how light interacted with human tissue. This curiosity became a lifelong focus and would eventually transform medical treatment for a highly stigmatised disease of the time: lupus vulgaris, or cutaneous tuberculosis.
In the 1890s, lupus vulgaris was one of the most persistent and disfiguring manifestations of tuberculosis, which was then a leading cause of death worldwide. The skin form of TB caused ulcerating lesions, often on the face, which led to long-term deformity, particularly in young patients. At the time, there was no reliable or humane treatment. Finsen hypothesised that light --specifically the chemical rays in the blue and ultraviolet spectrum could act directly on the bacteria and stimulate healing of the infected tissue.
Working initially with filtered sunlight, Finsen designed techniques to remove the heat-producing infrared rays and concentrate the short-wavelength radiation. As his understanding deepened, he transitioned to using carbon arc lamps, which allowed for controlled, high-intensity delivery of light even in low-sunlight conditions. In 1896, with support from the Danish government and scientific community, he founded the Finsen Medical Light Institute in Copenhagen. There, with a small team of physicians and nurses, he treated more than 1,000 patients suffering from lupus vulgaris over the next few years.
Phototherapy, the Nobel prize and global health impact
What set Finsen's work apart was its methodological rigour and reproducibility. His technique focused light beams onto the lesions for extended periods, often hours, under precise protocols. Patients experienced significant reduction in inflammation, healing of open lesions, and most importantly an arrest in disease progression. Many were children who had exhausted all other options. His clinical success offered proof that light could be used as medicine, a revolutionary idea in a period when most therapies were either surgical or pharmacological.
But Finsen's contributions were not only practical, they were conceptual breakthroughs. He was among the first to propose that external physical forces, not just chemicals or immune stimulation, could be harnessed in disease management. His ideas inspired future therapies including ultraviolet sterilisation, photodynamic therapy for certain cancers, and the now-routine phototherapy for neonatal jaundice.
Despite the growing recognition, Finsen's personal health deteriorated. By the early 1900s, he was unable to walk and conducted most of his work from bed, often dictating to assistants. Yet he continued to publish, consult, and treat patients until the end of his life. His declining health added urgency and poignancy to his scientific mission, and he became a symbol of resilience in the medical and public health communities across Europe.
His recognition by the Nobel Committee in 1903 was significant not just for its scientific merit but for the humanitarian impact of his work. Finsen was the third person to receive the Nobel Prize in Physiology or Medicine, following Emil von Behring and Ronald Ross. His award highlighted the growing international consensus that medicine must not only advance knowledge but reduce suffering in real and measurable ways.
Tragically, Finsen's own health issues prevented him from attending the Nobel Prize ceremony.
His legacy today
Finsen passed away the following year, in September 1904, at the age of just 43. His work outlived him. In the decades that followed, the Finsen lamp and its modified versions were used in hospitals throughout Europe and North America. The principles he established continue to influence treatment today. Phototherapy is now a standard of care in dermatology for conditions like psoriasis, vitiligo, and eczema, and it is also used in oncology, ophthalmology and neonatology.
Modern techniques such as narrowband UVB, laser therapies and blue light for acne all owe conceptual debts to Finsen. Even in infection control, ultraviolet germicidal irradiation -- now widely adopted in healthcare and public spaces -- rests on the same light-tissue interaction theories Finsen helped establish.
While the World Health Organization (WHO)does not name Finsen individually, its clinical guidelines for treating neonatal jaundice recommend phototherapy as a first-line, life-saving intervention. The global adoption of this therapy, especially in low- and middle-income countries, reflects Finsen's enduring influence.
Today, the Finsen Institute remains part of Copenhagen University Hospital. His former residence and laboratory have been preserved as historical landmarks. Statues and memorials in Denmark honour him not as a scientist who worked quietly, under immense personal strain, to expand the frontiers of medicine.