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Difference between chickenpox and smallpox

by Alivia Nyhan
Published: Last Updated on

They may be very similar, but the truth is that they are very different: smallpox and chickenpox are diseases caused by viruses that mainly affect the skin. Children primarily suffer from chickenpox. There is a vaccine that today is administered to the entire population. Still, the issue with smallpox is very different since the vaccine should no longer be helped because it is the only infectious disease considered eradicated.

From FastlyHealwe invite you to know in the following article the difference between chickenpox and smallpox, explaining all the symptoms, forms of contagion, treatment, conditions of prevention, and the current state of these diseases.

What are chickenpox and smallpox?

Chickenpox and smallpox are viral diseases whose most crucial manifestation is skin lesions.

In the case of chickenpox, it is caused by the varicella-zoster virus and smallpox by the variola major virus.

As we will see below, they can be differentiated by several aspects: symptoms, complications, forms of contagion, prevention, treatment, and the current state of the disease.

Chickenpox and smallpox: symptoms

When you come into contact with the chickenpox virus for the first time and suffer the disease, the following symptoms appear :

  • Fever (temperature greater than 38 ° C).
  • Body pain.
  • Inappetence.
  • Skin lesions: appear after 10 to 21 days of being infected. They begin as reddish spots or bumps, then turn into blisters or vesicles filled with clear fluid, which, when broken, give rise to scabs (which do not leave a scar if not scratched). Lesions may exist in all three phases at the same time.
  • Itch.
  • Lesions in the mucous membranes (mouth, nose, eyes, urethra, vagina, anus): blisters, ulcers.

The virus remains latent in some nerve ganglia and can reactivate as shingles, usually after several decades.

On the other hand, smallpox has the following symptoms:

  • There are no symptoms during the incubation period (7 to 17 days after infection).
  • Then some nonspecific symptoms begin with fever, body ache, headache, back pain, and vomiting.
  • Within a few days, skin lesions appear: they begin as red spots on the face and arms and then on the trunk, which later transform into pus-filled vesicles, and eventually scabs appear in their place that leave scars when they fall off very deep.
  • There may also be lesions in the mucosa of the mouth and nose, which end up being sores.

Chickenpox and smallpox: ways of contagion

Chickenpox can spread in two ways:

  • Through contact with the fluid that comes out of the blisters.
  • By drops from the respiratory tract (sneezing, coughing, secretions).

This is so from a couple of days before the skin lesions appear (during the last days of the incubation period) and until all the lesions are scabs, it is no longer contagious.

On the other hand, smallpox is contagious when the lesions are already present. It cannot be transmitted to other people during the incubation period. This transmission can be:

  • From respiratory droplets or secretions.
  • Through the air: can be spread through ventilation systems.
  • Although rare also for items (such as contaminated clothing and bedding).

Chickenpox and smallpox: treatment

Let’s see below what is the treatment of chickenpox and smallpox and how they differ:


Generally, when those affected are healthy children, no medication is necessary. Just keep them apart, so they do not infect others. At most, antihistamines or talcum powder are indicated to relieve itching and paracetamol (acetaminophen) in case of fever. Aspirin should never be given.

In any case, it is essential to maintain proper hydration, but different measures can be used to treat chickenpox in immunocompromised patients or those who may suffer complications:

  • Post-exposure vaccination: the chickenpox vaccine can be given up to 5 days after being in contact with someone who has this disease or with their secretions.
  • Acyclovir: It is an antiviral medication that, if administered in healthy children during the incubation period, can prevent the disease from appearing in its whole magnitude, but it is not frequent use. It can also be used in more severe or complicated cases to help resolve the infection, shorten the duration, or treat complications (such as encephalitis).
  • Corticosteroids: in case of complications, corticosteroids can be used to reduce inflammation in general, but they must be given in some instances, depending on the defenses, because their excessive use can also be harmful.
  • Antibiotics: they are used in superinfections of the skin or pneumonia.


  • As a first measure, the patient must be isolated to avoid infecting others.
  • The vaccine can be given up to 4 days after being in contact with someone sick, which can prevent symptoms from appearing or lessen their severity.
  • Maintain adequate hydration.
  • Treat symptoms with rest and antipyretics.
  • Antibiotics may be indicated in case of superinfection of the lesions or pneumonia.

Chickenpox and smallpox: complications

Chickenpox is usually a mild and self-limiting disease, but in very young children (under six months) in immunocompromised or elderly may appear complications like:

  • Pneumonia.
  • Superinfection of lesions.
  • Encephalitis.
  • Cerebelitis.
  • Coagulopathies.

It is essential to consult your doctor if the fever is very high (over 39 °) and does not go down, there is a worsening of the cough, dizziness, disorientation, profuse vomiting, stiff neck, very severe headache, the skin becomes very red and hot or do you consider it appropriate to see a professional.

As for smallpox, although most of the people who have had it have survived, it usually leaves profound scars on the face, arms, and trunk. People with low defenses and pregnant women were more susceptible to complications :

  • More severe illness, even to the point of death.
  • Blindness.

Chickenpox and smallpox: prevention

For both diseases, there is a vaccine.

The vaccine has been around for chickenpox since 1986, but there are still outbreaks every 4 or 5 years, especially in the late winter and early spring. And the reason that this disease continues to exist is that vaccination is not universal. That is, it is not mandatory in many countries. Therefore, new cases may arise. In addition, placing a single dose is not enough to avoid the disease 100%. Thus, two doses of the varicella vaccine are recommended. The first dose is given between 12 and 15 months of age and the second in children between 4 and 6. Likewise, the vaccine can be used to control epidemic outbreaks.

There is also another way to prevent chickenpox in people with low defenses or at high risk of contracting the disease, both in children and adults. It is an immunoglobulin, a protein manufactured specifically to prevent this disease.

On the other hand, smallpox was eradicated. This was in 1980 and is considered one of the most outstanding achievements of medicine. Before the vaccination and prevention campaigns were established, there were many cases of infection that could be complicated, disfigure the person and even be deadly. That is why children are no longer vaccinated. It is no longer necessary. In addition, it is a live virus vaccine, which can bring complications such as problems in the brain or heart, so if it is not extremely necessary, a new vaccination plan should not be established.

This article is merely informative. At FastlyHeal .com, we do not have the power to prescribe medical treatments or make any diagnosis. We invite you to see a doctor if you present any type of condition or discomfort.

If you want to read more articles similar on the Difference between chickenpox and smallpox, we recommend that you enter our Immune system category.

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