Mpox Basics — Symptoms, Vaccine, Prevention
Mpox (formerly called monkeypox) isn't a traditional STI — it can spread through any close skin contact. But in the 2022 global outbreak and continuing cases since, the vast majority of transmission has been through sexual contact, primarily among MSM (men who have sex with men). The good news: a vaccine exists, treatment exists, and outbreaks have been controllable when people get vaccinated and tested.
Here's the practical guide.
The short answer
- What it is: A viral infection caused by the monkeypox virus (now called MPXV); part of the same family as smallpox
- How it spreads: Skin-to-skin contact, especially during sex; respiratory droplets in prolonged close contact; contaminated objects (less common)
- Symptoms: Rash with characteristic pus-filled lesions, often on the genitals, anus, or face; fever, swollen lymph nodes, body aches
- Vaccine: JYNNEOS — two doses, 4 weeks apart; highly effective at preventing severe disease
- Treatment: Mostly supportive care; tecovirimat (TPOXX) for severe cases or high-risk patients
- Who's at highest risk: MSM with multiple partners, people with HIV, immunocompromised people
What mpox looks like
The hallmark is the rash, which often appears in stages:
Phase 1: Prodromal symptoms (sometimes absent)
- Fever, often abrupt
- Severe headache
- Swollen lymph nodes (an important distinguishing feature from chickenpox)
- Muscle aches and back pain
- Severe fatigue
- These last 1-3 days before the rash appears
Phase 2: Rash
The rash:
- Often starts on the genitals or anus (in 2022+ outbreak pattern)
- Can also appear on face, mouth, hands, feet, trunk
- Progresses through stages: flat → raised → fluid-filled blister → pus-filled → scab
- Lesions tend to be in the same stage of development at any given time (chickenpox lesions are in mixed stages)
- Painful — especially around the genitals, anus, mouth
- Lasts 2-4 weeks
Anatomical concentration in 2022+ outbreak
Many cases have presented with localized anogenital or oral lesions without widespread rash. This is a shift from the more disseminated rash seen in the historical disease pattern from West and Central Africa.
How mpox spreads
- Skin-to-skin contact with lesions — by far the most common
- Sexual contact — predominant route in 2022+ outbreak
- Respiratory droplets in prolonged close face-to-face contact
- Contaminated objects (towels, clothing, sex toys) — less common but possible
- Mother-to-fetus — rare
You can spread mpox from when symptoms first appear until all scabs have fallen off and new skin has formed.
When to suspect mpox
See a clinician promptly if you have:
- New painful rash, especially in genital/anal area
- Pus-filled lesions
- Fever + rash
- Swollen lymph nodes + rash
- Possible exposure to known mpox case
If lesions are around your mouth, hands, or face — get evaluated.
How mpox is diagnosed
- PCR test of a lesion swab — direct testing for the virus
- Done at clinics, hospitals, and increasingly at sexual health clinics
- Results typically in 1-3 days
- Don't pop or scrape lesions before testing
Treatment
Most cases
- Supportive care: pain management, hygiene, keeping lesions clean and dry
- Resolution in 2-4 weeks
- Most people recover without complications
Severe or high-risk cases
- Tecovirimat (TPOXX) — antiviral developed for smallpox; effective for mpox
- Available through expanded access protocols
- Given orally; some IV options
- Particularly important for HIV+ people, immunocompromised, severe cases
Pain management
Anogenital lesions can be very painful. Options:
- Topical anesthetics (lidocaine)
- Oral pain medication
- Sitz baths
- Stool softeners (to ease passage past anal lesions)
The JYNNEOS vaccine
JYNNEOS (also called MVA-BN, Imvanex in Europe) is a two-dose vaccine that uses a non-replicating live virus (vaccinia, smallpox-related but modified).
Schedule
- Dose 1: Initial
- Dose 2: 28 days later
- Full immunity ~14 days after dose 2
Effectiveness
- ~70-85% effective against mpox infection
- Higher effectiveness against severe disease
- May provide partial protection from a single dose
Who's recommended
- Pre-exposure (PrEP): MSM and transgender people with multiple partners, sex workers, people with HIV at risk, people with recent STI diagnosis, sex on premises venue attendees
- Post-exposure: Any close contact of a known mpox case (within 4-14 days, ideally < 4 days)
Side effects
- Injection-site soreness (most common)
- Fatigue, headache for 1-2 days
- Allergic reactions rare
Access
- Sexual health clinics (San Francisco, NYC, LA, Chicago, others have walk-in clinics)
- Health departments
- Some primary care providers
- Sometimes free; sometimes covered by insurance
Mpox and HIV
People with HIV — especially uncontrolled HIV or low CD4 counts — are at increased risk of:
- Severe mpox illness
- Prolonged infection
- Disseminated disease
- Death from mpox
Recommendations:
- HIV+ people should be among the first to get vaccinated
- HIV testing should be offered to anyone diagnosed with mpox
- Consider tecovirimat for HIV+ patients with mpox
What to do if exposed
- Within 4 days of exposure: Get JYNNEOS vaccine — most effective
- Within 4-14 days: Vaccine still recommended; may reduce severity
- Monitor for symptoms for 21 days
- If you develop symptoms: Isolate, get tested via PCR
- Avoid sexual contact until tested negative or fully recovered
Living with mpox during illness
Isolation
- Stay home from work/school
- Avoid close contact with others — especially anyone immunocompromised, pregnant, or under 8 years old
- Avoid contact with pets (some can get mpox)
- Sleep apart from partners
Hygiene
- Wash hands frequently
- Don't share towels, bedding, clothing
- Disinfect bathroom and high-touch surfaces
When can I have sex / be social again?
- After ALL lesions have scabbed AND scabs have fallen off AND new healthy skin has formed underneath
- Typically 2-4 weeks from rash onset
Mental health
- Mpox illness can be socially isolating and physically painful
- Pain + isolation + stigma can take a toll
- Mental health support is valuable
How to reduce risk
- Get vaccinated if eligible
- Limit anonymous partners during outbreaks if local cases are surging
- Check for visible rash before sexual contact (though early lesions can be subtle)
- Avoid skin-to-skin contact with anyone showing symptoms
- Wash sex toys with soap and water
- Practice good general hygiene
Mpox vs other rashes — how to tell them apart
| Mpox | Herpes | Syphilis (secondary) | Chickenpox | |
|---|---|---|---|---|
| Lesion type | Pus-filled, deep, indented center | Clear blisters in clusters | Often flat, red, can be on palms/soles | Mixed stages: vesicles, scabs |
| Pain | Significant, especially at lesions | Tingling/burning + sores | Usually painless | Itchy |
| Lymph nodes | Very swollen | Sometimes | Sometimes | Sometimes |
| Fever | Often before rash | Sometimes with first infection | Sometimes | Sometimes |
| Duration | 2-4 weeks | 7-14 days | Resolves spontaneously then comes back | 7-14 days |
| Distribution | Often genital/anal/face | Genital or oral | Can be widespread, palms/soles | Trunk-centered, spreads outward |
If you're not sure — get evaluated and tested. The treatment paths are different.
What's changed since the 2022 outbreak
- Vaccination became widely available — millions vaccinated in the US
- Cases dropped sharply after vaccination scale-up
- 2024-2026: Sporadic cases continue; periodic flare-ups in countries with low vaccine coverage
- Clade I outbreak in Central Africa (2024+) — different strain, generally more severe; spread to other countries; international concern
- Routine mpox testing is increasingly part of STI panels in some sexual health clinics
What to ask your provider
"Am I eligible for mpox vaccination?"
"When was my last dose? Do I need a second?"
"If I have a suspicious rash, where can I get tested?"
"I had a possible exposure — am I within the post-exposure prophylaxis window?"
Bottom line
Mpox is:
- A real risk for sexually active MSM, but increasingly under control
- Preventable with the two-dose JYNNEOS vaccine (~70-85% effective)
- Treatable — mostly supportive, with tecovirimat for severe cases
- Diagnosed by PCR swab of a lesion
- Most transmissible during the rash, until all lesions heal
If you're eligible, get vaccinated. If you have a new painful genital rash with fever, get tested. The mpox outbreak playbook works when people use it.
For more on prevention, see our PrEP vs PEP guide and HPV vaccine for adults over 26. For broader prevention strategy: do condoms prevent STIs?.
