Mpox causes signs and symptoms which usually begin within a week but can start 1–21 days after exposure. Symptoms typically last 2–4 weeks but may last longer in someone with a weakened immune system.
Common symptoms of mpox are:
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rash
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fever
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sore throat
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headache
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muscle aches
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back pain
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low energy
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swollen lymph nodes.
For some people, the first symptom of mpox is a rash, while others may have different symptoms first.
The rash begins as a flat sore which develops into a blister filled with liquid and may be itchy or painful. As the rash heals, the lesions dry up, crust over and fall off.
Some people may have one or a few skin lesions and others have hundreds or more. These can appear anywhere on the body such as the:
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palms of hands and soles of feet
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face, mouth and throat
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groin and genital areas
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anus.
Some people also have painful swelling of their rectum or pain and difficulty when peeing.
People with mpox are infectious and can pass the disease on to others until all sores have healed and a new layer of skin has formed.
Children, pregnant people and people with weak immune systems are at risk for complications from mpox.
Typically for mpox, fever, muscle aches and sore throat appear first. The mpox rash begins on the face and spreads over the body, extending to the palms of the hands and soles of the feet and evolves over 2-4 weeks in stages – macules, papules, vesicles, pustules. Lesions dip in the centre before crusting over. Scabs then fall off. Lymphadenopathy (swollen lymph nodes) is a classic feature of mpox. Some people can be infected without developing any symptoms.
In the context of the global outbreak of mpox which began in 2022 (caused mostly by Clade IIb virus), the illness begins differently in some people. In just over a half of cases, a rash may appear before or at the same time as other symptoms and does not always progress over the body. The first lesion can be in the groin, anus, or in or around the mouth.
People with mpox can become very sick. For example, the skin can become infected with bacteria leading to abscesses or serious skin damage. Other complications include pneumonia, corneal infection with loss of vision; pain or difficulty swallowing, vomiting and diarrhoea causing severe dehydration or malnutrition; sepsis (infection of the blood with a widespread inflammatory response in the body), inflammation of the brain (encephalitis), heart (myocarditis), rectum (proctitis), genital organs (balanitis) or urinary passages (urethritis), or death. Persons with immune suppression due to medication or medical conditions are at higher risk of serious illness and death due to mpox. People living with HIV that is not well-controlled or treated more often develop severe disease.