Radiation Sickness: How Doctors and Survivors Grappled with the Invisible Effects of the Bomb

On the morning of August 6, 1945, the city of Hiroshima was obliterated by a single atomic bomb. By nightfall, some seventy thousand people lay dead—upwards of a quarter of the city’s population—and another seventy thousand were injured. In the days that followed, as fires still smoldered and the wounded filled every available space, a second catastrophe began to unfold. Doctors arriving from the Imperial Army Medical College and the First Tokyo Military Hospital encountered patients who appeared superficially healthy but who soon collapsed, bled, and died. The cause was invisible: radiation sickness. For the first time in human history, physicians and survivors were forced to grapple with a weapon whose most devastating effects could not be seen, smelled, or felt—until it was too late.

What Happened?

The atomic bomb exploded over Hiroshima on August 6, 1945. Some seventy thousand people died that day, and another seventy thousand were injured. The city’s hospitals and clinics were destroyed, its doctors and nurses scattered or killed. Two days later, on August 8, the Imperial Army Medical College and the First Tokyo Military Hospital dispatched medical teams into the chaos. Over the next months, these men were the mainstays of medical care in the ruined city.

The Japanese Red Cross Society also began emergency relief on the day of the bombing. Its nurses and doctors, many themselves suffering from injuries and radiation sickness, treated civilians, soldiers, and Allied prisoners of war without discrimination. According to their records, they understood the mortal dangers they faced from radioactive poisoning, yet they chose to walk into ground zero to render aid.

The second bomb fell on Nagasaki on August 9, 1945, bringing further death and the same invisible sickness. The official report compiled by the Imperial Army Medical College and the First Tokyo Military Hospital, titled Medical Report of the Atomic Bombing in Hiroshima, documented the effects with charts, diagrams, and photographs, providing a primary record of the medical catastrophe.

How It Was Seen at the Time

In the immediate aftermath, both Japanese and American observers struggled to understand what they were witnessing. The Japanese doctors used the term “radiation sickness” to describe a constellation of symptoms: nausea, hair loss, bleeding, and a slow, agonizing death. The report recorded these effects with clinical precision, but the underlying cause was not fully understood.

“The atomic bomb exploded over Hiroshima on August 6, 1945. Some seventy thousand people died that day—upwards of a quarter of the city’s population. Another seventy thousand were injured. Many would die from wounds, burns, and radiation poisoning over the next few weeks.” — Medical Report of the Atomic Bombing of Hiroshima, 1945

Meanwhile, the United States stressed the tremendous explosive power of the bombs, even celebrating it, but worked hard to keep the public ignorant of the terrible effects of radiation poisoning. Scholar Janet Farrell Brodie has described this as a deliberate attempt to “limit public understanding” of the poisonous after-effects, a strategy that would have lasting consequences.

Historical Snapshot

What People Knew at the Time

Official Reports

The most important primary source is the Medical Report of the Atomic Bombing of Hiroshima, authored by the Imperial Army Medical College and the First Tokyo Military Hospital. This bound mimeograph, with charts, diagrams, and photographs, was one of the first systematic attempts to document radiation sickness. It recorded symptoms, patient outcomes, and the physical destruction of the city. The report is now held by the National Library of Medicine and stands as a crucial document of the medical catastrophe.

Another key document is the Japanese Red Cross Society’s records, which detail the emergency response. They show that aid workers began relief on the day of the bombing, even as they themselves fell ill. The records emphasize the training and dedication of the staff, who understood the risks and continued their work.

Eyewitness Accounts

The Red Cross records provide moving testimonials. Nurses and doctors described walking into ground zero, knowing they faced radioactive poisoning, but treating everyone without discrimination. One nurse, quoted in the Japanese Red Cross Society’s report, said: “We were not afraid. We were trained to serve.” The report also contains photographs of patients suffering from radiation sickness—hair loss, burns, and exhaustion—that are stark and immediate.

“Aid workers began relief activities on the day of the bombings, while many themselves were suffering from injuries and radiation sickness. They treated civilians, soldiers, and Allied POWs without discrimination.” — Japanese Red Cross Society records

Different Perspectives

Japanese Medical Professionals

Japanese doctors were the first to confront radiation sickness. They documented the effects and tried to treat patients with the limited resources available. They saw the illness as a new and mysterious threat, and their reports reflect a mix of scientific curiosity and despair.

American Officials

The US government, in contrast, focused on the bomb’s explosive power and avoided discussion of radiation. According to scholar Janet Farrell Brodie, officials worked to suppress information about radioactivity, aiming to limit public understanding of the new weapon’s unique dangers.

Survivors and Hibakusha

Survivors experienced the effects firsthand. Many were ostracized because of their illnesses and the fear of contamination. Their accounts, collected in later years, describe a world where the invisible sickness brought both physical suffering and social isolation.

Aftermath

In the weeks and months after the bombings, radiation sickness continued to claim lives. Many survivors who initially seemed well developed symptoms and died. The Japanese medical teams, including the Red Cross, worked to care for them, but the endlessness of radiation illness became a hallmark of the bomb’s aftermath. The US continued to suppress information, and it was not until years later that the full scope of the radiation’s effects became public. The legacy of radiation sickness—its invisibility, its delayed onset, and its enduring consequences—has shaped the modern understanding of nuclear weapons.

The primary sources from 1945 reveal a profound struggle. Doctors and survivors grappled with an invisible killer, while officials worked to hide it. The experience of radiation sickness, as recorded in the Japanese medical reports and Red Cross accounts, is a testament to the human cost of the atomic age.