Smallpox produced one of the most recognizable rashes in the history of medicine: deep, round, firm blisters that erupted first on the face and spread outward to the arms and legs, progressing in lockstep through clearly defined stages over about two weeks. The lesions were strikingly uniform, all reaching the same stage of development at roughly the same time in any given area of the body. That synchrony, combined with a centrifugal distribution pattern that concentrated the worst damage on the face and extremities rather than the trunk, made smallpox visually distinct from almost every other blistering illness. Although the disease was eradicated in 1980 and most people alive today have never seen a case, archived clinical photographs and detailed written descriptions give a thorough picture of what this rash looked like at every phase.
Before the Rash Appeared
Smallpox did not begin on the skin. After an incubation period of roughly seven to nineteen days following exposure, patients developed a sudden high fever, often spiking above 101°F, along with severe headache, backache, and sometimes vomiting. This prodromal phase lasted two to four days and was miserable enough that most patients were bedridden before a single spot appeared. The fever would then drop slightly, and the rash would begin, usually starting as small flat red spots inside the mouth and on the tongue. These oral lesions, called enanthem, broke open quickly and released large amounts of virus into the saliva, making the patient highly contagious right around the time the skin rash started showing up.
How the Rash Evolved Day by Day
The skin rash followed a remarkably predictable timeline, which is one of the reasons clinicians historically could identify smallpox with reasonable confidence just by looking at it. Within a day or two of the oral spots, small flat red marks, or macules, appeared on the face, particularly the forehead and cheeks. Over the next twenty-four hours, these spread down the arms and onto the legs. The trunk was involved too, but less densely. That pattern of heavier involvement on the face and limbs compared to the torso is called a centrifugal distribution, and it was one of smallpox’s hallmark features.
Over the following days, the flat spots raised into firm papules, then filled with clear fluid to become vesicles, and finally turned into opaque, pus-filled pustules. Each stage took roughly one to two days. By about the eighth or ninth day after the rash first appeared, the pustules were at their peak: tense, round, and deeply embedded in the skin, often described as feeling like small pellets or BBs under the surface. They had a characteristic dimpled center, sometimes called umbilication, where the middle of each blister was slightly depressed. This gave the individual lesions a distinctive look quite different from the thin-walled, superficial blisters of chickenpox.
Around day ten or eleven, the pustules began to flatten, dry, and form crusts. The scabs were thick and dark, and they took another one to two weeks to separate from the skin. The patient remained contagious until every last scab had fallen off. Beneath those crusts, new skin was forming, but it was often depigmented and pitted, especially on the face.
What Made the Lesions Look Different from Other Rashes
Three visual features distinguished smallpox from the diseases most often confused with it. The first was synchrony. If you looked at any particular area of the body, say the forearm, all the lesions there were at the same developmental stage. They had all become papules together, all filled with fluid together, and all scabbed over together. This stood in sharp contrast to chickenpox, where a single patch of skin might show fresh red bumps right next to mature blisters right next to healing crusts, all at the same time.
The second was depth. Smallpox lesions were firmly rooted in the dermis, the deeper layer of skin. When you ran a finger over them, they felt hard and embedded rather than fragile and superficial. Chickenpox blisters, by comparison, sat on the surface and could be easily ruptured. The depth of smallpox lesions is also the reason they were so much more likely to scar.
The third was distribution. Smallpox was densest on the face, the palms of the hands, and the soles of the feet. The involvement of palms and soles was a strong diagnostic clue, because many other viral rashes spare those areas. A patient covered in blisters with heavy involvement on the face and hands and relatively lighter coverage on the stomach and back was a classic smallpox presentation.
The Different Clinical Types
Not every case of smallpox looked the same. Clinicians recognized several distinct presentations, and the visual differences between them could be dramatic.
- Ordinary smallpox: This was the most common form, accounting for roughly 90 percent of cases in unvaccinated people. It followed the classic progression described above: raised, firm, well-separated lesions moving through macules, papules, vesicles, pustules, and crusts. It could be further subdivided by severity into discrete (lesions remained separate and countable), semiconfluent (lesions merged in some areas, especially the face), and confluent (lesions ran together into sheets, particularly on the face and forearms). Confluent ordinary smallpox looked devastating, with the face swollen and nearly unrecognizable beneath a continuous sheet of pustules.
- Modified smallpox: This occurred in people who had some prior immunity, usually from vaccination. The rash was milder, with fewer lesions that progressed faster and often did not develop the classic deep pustular stage. The lesions were more superficial, and the illness resolved more quickly. It was sometimes difficult to distinguish from chickenpox at a glance.
- Flat (malignant) smallpox: Instead of raised firm pustules, this type produced soft, flat, velvety lesions that never fully elevated above the skin surface. The skin looked as though it had been slowly confluently burned. Patients were often severely toxic, with sustained high fever and a dusky, swollen appearance. This form was almost always fatal.
- Hemorrhagic smallpox: The rarest and most rapidly lethal type. Instead of the usual blister progression, patients developed widespread bleeding into the skin and mucous membranes. The skin appeared darkly bruised, sometimes nearly black, with blood suffusing the base of early lesions rather than clear fluid. Many patients died before the rash even fully developed, sometimes within five or six days of symptom onset. Hemorrhagic cases were especially common in pregnant women.
The visual range across these subtypes was enormous. A person with discrete ordinary smallpox might have a few hundred well-spaced pimple-like lesions on the face and arms. A person with confluent ordinary smallpox might be unrecognizable. And a person with hemorrhagic smallpox might look as if they were suffering from a catastrophic bleeding disorder rather than an infection. All were caused by the same virus, variola.
Why Smallpox Photographs Can Be Hard to Find
Smallpox was eradicated before digital photography became widespread, so most surviving images are from mid-twentieth-century public health archives. The World Health Organization, the U.S. Centers for Disease Control and Prevention, and a handful of academic dermatology atlases maintain the most reliable collections. Many of the photographs were taken during the global eradication campaign in the 1960s and 1970s, and they tend to depict patients in South Asia and sub-Saharan Africa where the final outbreaks occurred.
If you search online, be cautious. A significant number of images labeled “smallpox” on unvetted websites actually show monkeypox (now called mpox), chickenpox, or other vesicular diseases. The most reliable way to see authentic clinical photographs is through CDC’s archived smallpox image library or WHO publications from the eradication era. Images from those sources are taken in clinical settings with confirmed diagnoses and represent the full spectrum of disease severity.
The Scars That Lasted a Lifetime
For survivors, the rash was not the end of the story. Most people who recovered from ordinary smallpox were left with permanent scars, particularly on the face. These scars had a characteristic appearance: round, depressed pits with sharply defined edges, often described as having a cobblestone texture when many were clustered together.1Plastic & Reconstructive Surgery. Laser Resurfacing of Smallpox Scars The pitting was deep enough to be visible from across a room and could be socially devastating, especially for women in cultures where facial appearance carried heavy social weight.
The reason the scars were so deep has to do with where the virus did its damage. The leading theory, first proposed in 1952 and still considered the best explanation, is that smallpox destroyed the sebaceous glands in the skin. These tiny oil-producing glands sit in the dermis, and their destruction left permanent pits because the tissue they occupied could not regenerate. Interestingly, variola virus particles have never actually been identified inside sebaceous glands or even in the dermis itself, so the exact mechanism remains somewhat speculative even decades after the disease was eradicated.2PubMed. The scarring mechanism of smallpox What is clear is that the scarring was worst on the face, where sebaceous glands are most concentrated, and lighter on areas like the limbs where those glands are sparser. The trunk, despite often having fewer lesions, also tended to scar less severely.
Scarring varied in severity depending on the type and confluency of the disease. Patients with discrete ordinary smallpox might have scattered pockmarks. Those with confluent disease could have their entire facial skin surface pitted and uneven, with the scars running together into broad depressed areas. Flat and hemorrhagic types were so often fatal that scarring was less of a concern, though the rare survivors of flat smallpox could be left with extensive disfigurement.
Depigmentation was another common long-term effect. The healed areas were often lighter than the surrounding skin, making scars especially visible in people with darker complexions. Some survivors also lost eyelashes or eyebrows permanently when lesions destroyed the hair follicles in those areas. Blindness from corneal scarring was another feared complication when the rash involved the eyes.
The Vaccination Scar and How It Differed
Many people born before the 1970s or 1980s carry a round scar on their upper arm from the smallpox vaccine. This mark looks nothing like a smallpox scar. The vaccination scar is typically a single, slightly raised or indented circular area, often about the size of a pencil eraser, on the deltoid of one arm. It results from a localized skin reaction to the vaccinia virus (a related but much milder virus used in the vaccine), which was introduced by pricking the skin multiple times with a bifurcated needle.
The vaccine site went through its own miniature version of a pox lesion: a papule formed, then a vesicle, then a pustule, then a scab. The whole process took about three weeks. The formation of this scar was actually considered evidence that the vaccination had worked, serving as a visible marker of a successful immune response.3PubMed Central. The mark of success: The role of vaccine-induced skin scar formation for BCG and smallpox vaccine-associated clinical benefits People whose vaccination site healed without a scar were sometimes re-vaccinated because the absence of a mark raised doubts about whether the vaccine had taken.
The vaccination scar is sometimes confused with the BCG scar from tuberculosis vaccination, which is also typically on the upper arm. In countries that administered both vaccines, individuals might carry two similar-looking round scars. The smallpox vaccine scar tends to be slightly larger and more irregular in outline, sometimes with a radiating pattern from the multiple needle pricks, while the BCG scar is usually smoother and smaller. In practical terms, if you are trying to figure out what a scar on an older relative’s arm is from, location and the person’s birth year are the most helpful clues: routine smallpox vaccination ended in most countries by the early 1970s for the general public.
Distinguishing Smallpox from Lookalike Diseases
Because smallpox has been eradicated, any case of a widespread blistering rash today is not smallpox. But clinicians are still trained to recognize the visual pattern, partly because of bioterrorism concerns and partly because other pox viruses, especially mpox, produce rashes that can look similar to an untrained eye.
The key visual differences between smallpox and chickenpox come down to the features already described: depth, synchrony, and distribution. Chickenpox blisters are shallow, appear in successive crops so that lesions at all stages coexist on the same patch of skin, and tend to be heaviest on the trunk rather than the face and limbs. Chickenpox also rarely involves the palms and soles. A clinician looking at photographs of the two diseases side by side would find them fairly easy to tell apart, but in the early stages, when only a few spots have appeared, the distinction was harder. This is one reason the WHO eradication campaign relied so heavily on laboratory confirmation alongside clinical examination.
Mpox, which gained global attention during the 2022 outbreak, presents more of a visual challenge. Its lesions go through the same stages as smallpox and are also deep and firm. The two most reliable distinguishing features historically were lymphadenopathy (swollen lymph nodes, prominent in mpox but typically absent in smallpox) and the degree of synchrony (mpox lesions can be slightly less uniform in their staging). In practice, without laboratory testing, even experienced clinicians found the two diseases difficult to separate based on appearance alone, which is part of why variola’s eradication was confirmed through laboratory means rather than just clinical observation.
Smallpox in Art and Historical Records
Before photography, the appearance of smallpox was captured in paintings, engravings, and written clinical descriptions. Some of the most detailed visual records come from eighteenth- and nineteenth-century medical illustrations, which were painstakingly hand-drawn and colored to show the progression of lesions. These illustrations, found in texts by physicians involved in the early vaccination campaigns, are strikingly consistent with the photographs taken a century or more later, suggesting that the clinical presentation of variola major was remarkably stable over time.
Smallpox scars also appear in historical portraiture and death masks, sometimes deliberately and sometimes inadvertently. Numerous historical figures were known to bear prominent pockmarks, and in some portraits the scars are visible despite the artist’s best efforts at flattery. The faces on pre-Columbian ceramic vessels from the Americas have been interpreted by some archaeologists as depicting smallpox lesions, though this remains debated. What is not debated is that for thousands of years, the pitted face of a smallpox survivor was one of the most instantly recognizable marks a human being could carry, visible from a distance and impossible to conceal. The eradication of smallpox did not just eliminate a deadly disease; it eliminated one of the most visible forms of human disfigurement in recorded history.