Overview
Mpox is a viral illness that causes a painful rash or sores on the skin, in the mouth or around the genitals, usually alongside fever, headache and swollen glands. It is caused by the monkeypox virus, which belongs to the same family as the virus that caused smallpox.
WHO states that most people recover within 2 to 4 weeks. The illness can be serious in children, in pregnant people and in people whose immune systems are weakened, particularly by untreated HIV.
Disease Summary
- Category
- Infectious Disease
- Cause
- Monkeypox virus (MPXV)
- Transmission
- Close contact with lesions, fluids or contaminated items
- Body System
- Skin
- Preventable
- Yes
- Curable
- Yes
Symptoms
Common Symptoms
Flu-like symptoms usually come first, with the rash following 1 to 4 days later. WHO states that symptoms begin 1 to 21 days after exposure.
Rash or Sores
The rash starts as flat spots, becomes fluid-filled blisters, then crusts over. WHO states it commonly begins on the face and spreads to the palms, soles and genitals.
Fever
Fever usually appears before the rash and settles as the rash develops.
Headache
Listed by both WHO and CDC among the early symptoms.
Muscle Aches and Back Pain
Aching muscles and a painful back are common in the first days of illness.
Swollen Lymph Nodes
Swollen glands are a distinguishing feature that helps separate mpox from chickenpox.
Low Energy and Exhaustion
Marked tiredness is listed by WHO and CDC among the usual symptoms.
Sore Throat, Congestion or Cough
CDC lists these respiratory symptoms among those that may occur.
Painful Sores in the Mouth or Genital Area
Sores in the mouth, anus or genitals can be more painful than the skin rash and can make eating, passing urine or opening the bowels difficult.
Danger Signs
Seek urgent medical attention immediately if any of the following symptoms develop.
Eye Pain, Redness or Change in Vision
WHO lists corneal infection causing vision loss among the complications. Any eye involvement needs urgent specialist assessment.
Lesions That Merge or Turn Black
CDC lists merging and dying lesions among the features of severe disease.
Difficulty Breathing
WHO lists pneumonia among the complications of mpox.
Confusion or Seizures
WHO and CDC both list encephalitis, inflammation of the brain, among severe manifestations.
Chest Pain
Both agencies list inflammation of the heart muscle among severe manifestations.
Difficulty Swallowing or Signs of Sepsis
WHO lists swallowing difficulty and sepsis among complications. Being unable to drink is a reason for hospital care.
Diagnosis
Examination of the Rash and Mucous Membranes
WHO states that mpox can be hard to identify because other conditions look similar, and that the best specimens come directly from the rash, so a full skin, mouth, anal and genital examination guides testing.
Exposure History Over 21 Days
CDC advises watching for symptoms for 21 days after last exposure, because illness usually begins within that window.
PCR Confirmation
WHO states that the preferred laboratory test is detection of viral DNA by polymerase chain reaction. Mpox is not diagnosed on appearance alone.
Determining the Clade
CDC performs clade-specific testing because the two clades differ in severity, and the result shapes the public health response.
Testing for Look-Alikes and Co-Infections
WHO advises offering HIV testing to adults with mpox, and considering tests for chickenpox, syphilis and herpes, both to find other causes and to find co-infections that raise the risk of severe illness.
Laboratory Tests
PCR on a Lesion Swab
The recommended test. CDC advises swabbing two to three separate lesions vigorously. A positive result confirms mpox.
Clade-Specific PCR
Distinguishes clade I from clade II. CDC reports a case fatality of 2.5% or less for clade I and under 0.1% for clade II.
PCR on a Throat or Anal Swab
WHO states these may be used when no skin lesions are visible.
HIV Test
WHO states HIV testing should be offered to adults with mpox, because uncontrolled HIV markedly raises the risk of severe disease and death.
Tests for Chickenpox and Syphilis
WHO recommends considering these where feasible, because both can look like mpox and both can occur at the same time.
Treatment
Pain Control Started Early
CDC states that pain control should begin early in the illness, using topical treatments and pain-relieving medicines. Mouth and genital sores in particular can be severe and deserve proper treatment.
Skin, Fluid and Nutrition Care
WHO describes supportive care with close attention to nutrition, hydration and skin care as the core of treatment. Most people need nothing more.
Hospital Care for Severe Disease
Needed for eye involvement, extensive or merging lesions, breathing difficulty, inability to drink, or signs of sepsis.
Antiviral Medicines in Selected Cases
WHO states there is no proven effective antiviral treatment for mpox. CDC reports that trials found tecovirimat safe but that it did not shorten the time for lesions to heal, and now reserves it for specific high-risk situations under specialist advice.
Continuing HIV Treatment
WHO states that people living with HIV should continue their antiretroviral therapy during mpox illness.
Prevention
Vaccination for people at risk
WHO reports that two doses of the MVA-BN vaccine reduce the chance of getting mpox by 82%, and one dose by 76%.
Vaccination after a known exposure
WHO advises vaccination within four days of exposure, or within 14 days if no symptoms have developed.
Avoid close contact with someone who has mpox
CDC advises not kissing, hugging, cuddling or having sex with a person who has mpox, and not touching their rash or scabs.
Do not share personal or household items
CDC advises against sharing utensils, dishes and cups, and against handling the bedding, towels or clothing of someone with mpox.
Wash hands often
CDC advises washing hands frequently with soap and water or using an alcohol-based hand rub, particularly after any contact with a person or their belongings.
Isolate until the skin has healed
WHO advises staying home from the onset of symptoms until the lesions have healed and the scabs have fallen off.
Risk Factors
People with Weakened Immunity
WHO states this group is at higher risk of serious illness and death.
- People living with HIV that is not well controlled
- People with a CD4 count under 200 cells per cubic millimetre
- Transplant recipients and people on immune-suppressing medicines
- People with eczema or atopic dermatitis, who are at risk of widespread infection
Children and Pregnant People
Both WHO and CDC name these groups among those at higher risk of severe disease.
- Children, particularly infants under one year
- Children who are also malnourished
- Pregnant people, who can pass the virus to the fetus
- Newborns, who can be infected during and after birth
People with Higher Exposure
Certain settings and roles bring more close contact with cases.
- People with multiple sexual partners
- Sex workers and their clients
- Health workers caring for people with mpox
- Household members of someone with mpox
Complications
Bacterial Skin Infection
WHO lists bacterial skin infections and abscesses among the complications, which is why lesions should not be scratched or burst.
Pneumonia
WHO lists pneumonia among the complications of mpox.
Eye Infection and Vision Loss
WHO lists infection of the cornea causing loss of vision. This is why eye symptoms are treated as urgent.
Inflammation of the Brain or Heart
WHO lists both encephalitis and myocarditis among the complications.
Sepsis
WHO lists sepsis among the complications of severe mpox.
Painful Inflammation of the Rectum or Genitals
WHO lists proctitis, balanitis and urethritis, which can make opening the bowels or passing urine extremely painful.
When to Seek Medical Care
Any New or Unexplained Rash
CDC advises seeing a health worker for a new or unexplained rash, especially after contact with someone who has mpox.
Immediately After a Known Exposure
Vaccination after exposure works best within four days, so do not wait for symptoms to appear.
As Soon as Lesions Become Painful
CDC states pain control should begin early, so this is a reason to seek care rather than to endure it.
Any Eye Pain, Redness or Blurred Vision
Eye involvement can lead to permanent loss of sight and needs same-day specialist assessment.
If You Are Pregnant, a Young Child, or Immunocompromised
These groups should seek care when symptoms begin rather than waiting to see how the illness develops.
Prognosis
Most People Recover in Two to Four Weeks
Both WHO and CDC state that most people with mpox recover fully within 2 to 4 weeks.
Outcome Depends on the Clade
CDC reports a case fatality rate of 2.5% or less for clade I and under 0.1% for clade II, and states that both are low when good supportive care is provided.
Scarring Can Remain
Deep lesions may leave marks, which is a further reason not to scratch or pick at them.
Risk Concentrates in Specific Groups
CDC reports that deaths occur primarily in immunocompromised people, children with malnutrition and people with other health conditions.
Differential Diagnosis
Chickenpox
Chickenpox lesions appear in successive crops at different stages, while mpox lesions progress together, and mpox more often causes markedly swollen glands.
Herpes Simplex
Herpes causes grouped blisters and ulcers that recur at the same site, and is separated by a specific herpes test.
Syphilis
Genital and mouth ulcers can look identical, which is why WHO advises considering syphilis testing alongside mpox testing.
Scabies
Scabies causes intense itching and burrows between the fingers, without the fever, swollen glands and pustules of mpox.
Drug Reactions and Allergic Rashes
These follow a new medicine or exposure and lack the stepwise progression from flat spot to blister to crust.
References
World Health Organization: Mpox
WHO fact sheet on transmission, symptoms, testing, treatment and prevention.
World Health Organization: Mpox vaccines
WHO questions and answers on the available vaccines, who should receive them and how effective they are.
CDC: Clinical Overview of Clade I and Clade II Monkeypox
Clinical features, severity by clade, complications and treatment considerations.
CDC: Signs and Symptoms of Monkeypox
The pattern and timing of symptoms and how long a person remains infectious.
Frequently Asked Questions
How long does mpox last, and how long am I infectious?
WHO states most people recover within 2 to 4 weeks, and that the rash itself can last that long. CDC states a person can spread mpox from the time symptoms start until the rash has fully healed and a fresh layer of skin has formed.
Is there a vaccine, and can I have it after being exposed?
Yes to both. WHO reports that two doses of the MVA-BN vaccine reduce the chance of getting mpox by 82%. WHO advises vaccination within four days of an exposure, or within 14 days if no symptoms have developed.
Is there a medicine that cures mpox?
WHO states there is no proven effective antiviral treatment for mpox, and that care is supportive, with attention to pain, fever, nutrition, hydration and the skin. CDC reports that trials found tecovirimat safe but that it did not shorten the time for lesions to heal.
Is mpox a sexually transmitted infection?
Not exactly. Mpox spreads through close physical contact of any kind, including skin-to-skin, face-to-face and sexual contact, and also through contaminated bedding, towels and clothing. CDC notes that the clade II outbreak has been almost exclusively associated with sexual contact, but non-sexual routes are real.
Can mpox spread through the air like COVID-19?
CDC states that mpox is not known to spread in settings where only respiratory spread is possible. Contact with saliva and secretions during close face-to-face contact is a route, but casual presence in the same room is not.