A rash on the palms and soles is one of the most distinctive clues in medicine, and in sexual health it points hard to secondary syphilis. Most other rashes spare the palms and soles, so when those areas are involved, syphilis moves to the top of the list. Eczema and certain viral rashes can mimic it, but only a blood test settles which one it is.
Treponema pallidum
| Item | Value |
|---|---|
| Syphilis | curable — Treponema pallidum |
The short list: what causes a palm-and-sole rash
Among sexually transmitted infections, syphilis in its secondary stage is the one that classically produces a rash on the palms and soles, close to a signature finding. The non-STI causes that can also hit the hands and feet are mainly eczema and some viral rashes CDC. These overlap enough that you can't reliably tell them apart by looking, so a syphilis blood test is the sensible next move whenever your palms or soles break out.
Which STIs cause a rash on the palms and soles
Syphilis — the main STI cause
Syphilis is caused by the bacterium Treponema pallidum, and antibiotics will clear it. It moves through stages, and the palm-and-sole rash belongs to the second one. The first stage usually shows up as one or more painless, firm, round sores called chancres at the spot where the bacteria entered — the penis, vagina, anus, rectum, lips, or mouth. That sore typically appears around three weeks after exposure, with an incubation window that can run anywhere from about ten to ninety days. The chancre lasts a few weeks and then heals on its own whether or not it's treated, so people miss it and assume nothing's wrong.
Secondary syphilis is the stage that brings the rash. It's typically rough to the touch and red or reddish-brown, and it can appear on the palms and soles, the trunk, or both. Unlike most rashes, it usually doesn't itch, which throws people off. It often travels with other symptoms: fever, swollen lymph nodes, sore throat, patchy hair loss, headache, weight loss, muscle aches, and a wrung-out fatigue. You may also see mucous-membrane lesions — sores or grayish patches inside the mouth or on the genitals. When a non-itchy palm-and-sole rash shows up alongside feeling broadly unwell, clinicians treat it as syphilis until a test proves otherwise.
If secondary syphilis isn't treated, the rash fades and the infection slides into the latent stage, where there are no symptoms at all but the bacteria persist for years and are still detectable on a blood test. People often don't realize they're carrying it. If you're pregnant, this matters especially — untreated syphilis can pass to the baby, so screening and treatment in pregnancy are a separate, important conversation covered under syphilis in pregnancy.
When it's NOT an STI
A rash on the hands and feet has plenty of non-sexual explanations, and most of them are far more common than syphilis. Eczema (dyshidrotic or hand eczema) tends to be intensely itchy, with small fluid-filled blisters or dry, cracked, scaly skin on the palms, fingers, and soles, and it often comes and goes with triggers like soap, stress, or weather. Several viral rashes can also involve the hands and feet, sometimes with sores in the mouth and a low fever. These conditions are real and worth treating, but they're not sexually transmitted.
A palm-and-sole rash is enough of a syphilis hallmark to warrant a syphilis blood test even when eczema or a virus seems likely. A rash that's non-itchy, painless, and paired with feeling generally unwell tilts toward syphilis, but those clues aren't reliable enough to bet on.
How to tell them apart
You mostly can't tell by sight. The discriminating features below point in useful directions, but they overlap too much to be definitive, and syphilis is frequently silent or subtle. A test is what settles which one, if any, it is.
- Itch: Eczema is usually very itchy; secondary syphilis usually isn't.
- Texture and color: Syphilis tends to be rough, flat-to-raised, and reddish-brown; eczema is often blistered, scaly, or cracked.
- Company it keeps: Syphilis frequently brings fever, swollen lymph nodes, sore throat, hair loss, and fatigue; an isolated itchy hand rash with no other symptoms leans away from it.
- Recent exposure: A new sexual partner in the prior weeks to months, especially with a painless sore that healed, raises the odds of syphilis.
- Timing: A chancre about three weeks after exposure followed weeks later by the rash fits the syphilis timeline.
Side-by-side comparison
| Feature | Secondary syphilis | Eczema (hand/dyshidrotic) | Viral rash |
|---|---|---|---|
| Itch | Usually none | Often intense | Variable |
| Appearance | Rough, red/reddish-brown, flat or slightly raised | Blisters, scaling, cracks | Spots or blisters, sometimes mouth sores |
| Whole-body symptoms | Common (fever, swollen nodes, sore throat, hair loss, fatigue) | Rare | Sometimes (fever, malaise) |
| Sexual transmission | Yes | No | No |
| How it's confirmed | Two syphilis blood tests | Clinical exam | Clinical exam, sometimes viral testing |
How it's tested
Diagnosing syphilis takes two blood tests: a nontreponemal test (RPR or VDRL) plus a treponemal test (TP-PA, FTA-ABS, EIA, or CIA). The two are paired because either alone can mislead, so labs confirm a positive with the second method CDC, 2024. In practice, testing is a blood draw, often alongside a urine sample or a quick exam depending on what else is suspected. It's free or low-cost at health departments, Planned Parenthood, and Title X clinics, with results usually back in a few days. For the full how-to, get tested, and if you're counting days since a possible exposure, see when to test after exposure.
What to do next
If a test confirms syphilis, the cure is penicillin — specifically benzathine penicillin G given as a single intramuscular injection for early-stage disease (primary, secondary, and early latent), and three weekly injections for late or unknown-duration infection CDC treatment guidelines. The correct product is benzathine penicillin G (Bicillin L-A). The combination product Bicillin C-R is not an acceptable substitute and has caused treatment failures CDC. There is no oral drug that dependably replaces the injection CDC, latent syphilis. Don't try to treat this at home; you need a clinician to confirm the stage and give the right shot.
Red flags — when to get seen urgently
- A non-itchy rash on your palms and soles, especially with fever, swollen lymph nodes, or hair loss.
- A painless sore on the genitals, anus, or mouth in the recent past, even one that already healed.
- Any rash on the hands and feet if you're pregnant, given the risk to the baby.
- New neurological symptoms (vision changes, severe headache, confusion) alongside a rash — get evaluated promptly.
- A rash that worsens fast, blisters widely, or comes with mouth sores and inability to eat or drink.