Syphilis test and treatment (Treponema pallidum testing and antibiotic treatment)
A blood test (and sometimes a swab from a sore) to check for syphilis, an infection that can be silent but serious if untreated, with antibiotic treatment that cures it.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- Syphilis can be silent yet serious, so a blood test is the only reliable way to know, even without symptoms.
- It is treatable and curable, usually with penicillin injections; the number depends on the stage.
- A test taken too soon after exposure can miss it, so timing matters and a repeat blood test is sometimes advised.
- Free, confidential testing, treatment and partner notification are available on the NHS, including screening in pregnancy.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your specialist will give you advice for your situation.
Finds an infection that can be silent, so it can be treated before it causes serious harm
A blood test alone may be too early to detect very recent infection; a swab from a sore can confirm it sooner.
A blood test from the arm takes a few minutes. You can carry on with your day. A swab from a sore is quick and only mildly uncomfortable.
Injection treatment in clinic with clear advice on when sex is safe again.
A blood test from the arm takes a few minutes. You can carry on with your day. A swab from a sore is quick and...
Treatment is one or more penicillin injections. The site may feel sore. Flu-like symptoms can occur in the first...
Avoid sex until the clinic says it is safe, usually until treatment is complete and any sore has fully healed, to...
You will have repeat blood tests over several months. A falling result confirms the treatment is working. The...
What is a syphilis test and treatment?
Syphilis is an infection caused by a bacterium called Treponema pallidum. It is passed on through vaginal, anal or oral sex, and through close skin contact with a syphilis sore.
Syphilis can be silent. Early signs, such as a usually not painful sore or a rash, often come and go on their own, but the infection stays in the body if it is not treated. Over months or years, untreated syphilis can cause serious problems affecting the heart, brain and nervous system. This is why testing matters even when you feel well.
The main test is a blood test, sometimes with a swab from a sore if you have one. If syphilis is found, it is treated and cured with antibiotics, usually penicillin injections. The number of injections depends on how long you have had the infection.
NHS sexual health (genitourinary medicine, or GUM) clinics offer testing and treatment free and confidentially, and syphilis is also screened for in pregnancy. You do not need to pay or get a GP referral.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
NHS sexual health clinic vs private testing
| Point | NHS clinic | Private |
|---|---|---|
| Cost | Free | You pay |
| Staging and treatment | Done in clinic | Check it is offered |
| Follow-up blood tests | Arranged | Check included |
| Partner notification | Yes, offered | Varies |
Syphilis needs careful staging, injection treatment and follow-up blood tests over months. NHS clinics provide all of this free; a private test alone does not, so check where treatment and follow-up will happen.
Preparing for your treatment
- Think about timing: a blood test very soon after exposure can be falsely negative, so ask the clinic when to test.
- Mention any sore, rash, or flu-like illness, and when you noticed it, as this helps staging.
- Note when you last had sex and with whom if you can, to help partner notification.
- Tell the clinic if you are pregnant or might be, as syphilis in pregnancy needs prompt treatment.
- Tell the clinic about any penicillin allergy, so treatment can be planned safely.
- Be ready to attend in person for treatment, as injections are given in clinic.
- You do not need ID or proof of address, and you do not have to share your GP's details if you prefer not to.
What happens
At a clinic, a clinician will ask about symptoms and recent sexual contacts in confidence, and may examine any sore or rash. This helps work out the stage of infection.
A blood sample is taken from your arm. If you have a sore, a swab may also be taken from it. Samples go to a laboratory.
If syphilis is confirmed, treatment is usually one or more penicillin injections into a muscle, given in clinic. You will be told how many you need based on the stage. After treatment, you will have follow-up blood tests over several months to confirm the infection is clearing.
If you are pregnant or penicillin-allergic, the clinic will plan treatment carefully, as both situations need extra attention.
Is this treatment right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- A blood test alone may be too early to detect very recent infection; a swab from a sore can confirm it sooner.
- A private test alone is the wrong choice if it does not include staging, treatment and follow-up blood tests.
- Self-testing is not suitable if you have a sore, rash or symptoms that need examination and staging.
- A single test is not enough if you have ongoing risk; repeat and regular testing may be needed.
Delay or rearrange if…
- It is very soon after the exposure you are worried about, as a too-early blood test can be falsely negative; ask about timing.
- You have neurological symptoms (severe headache, vision or hearing change, weakness), which need urgent assessment.
- You are pregnant and have not yet been assessed, as syphilis in pregnancy needs prompt specialist treatment.
- You cannot attend in person for treatment and the follow-up blood tests that confirm cure.
Alternatives to discuss
- A full sexual health screen covering several infections at once.
- Testing and treatment through a free NHS sexual health clinic rather than a private provider.
- Pregnancy screening, which routinely includes syphilis testing.
- Waiting and retesting at the right time if you have tested very early after exposure.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Benefits
- Finds an infection that can be silent, so it can be treated before it causes serious harm
- Treatment cures the infection and prevents long-term damage to the heart, brain and nerves
- Protects partners through treatment and partner notification
- In pregnancy, treatment protects the baby from serious harm
- Follow-up blood tests confirm the treatment is working
- Free and confidential on the NHS, with no need to pay or be judged
Risks & complications
- Brief discomfort or bruising from the blood test
- Soreness at the injection site after treatment
- Flu-like symptoms (fever, headache, aching) in the first 24 hours after treatment as the body reacts to the infection clearing
- A test taken too early can be falsely negative, so infection may be missed
- Needing a repeat blood test because it was done too soon after exposure
- Anxiety while waiting for results or telling partners
- Side effects from alternative antibiotics if you cannot have penicillin
- A serious allergic reaction to penicillin
- Late diagnosis, where damage to the heart, brain or nerves has already occurred and may not fully reverse
Two points matter most. First, timing: a blood test soon after exposure can miss infection, so a repeat test is sometimes advised. Second, the flu-like reaction in the first day after treatment (the Jarisch-Herxheimer reaction) is common and expected as the infection clears; it is not an allergy, but tell the clinic about any penicillin allergy beforehand so treatment is planned safely.
Published figures to discuss
Syphilis blood tests are accurate when taken at the right time, but very recent infection can be missed, which is why repeat testing is sometimes advised. Treatment with penicillin is highly effective, especially in early infection, but how completely someone recovers depends on the stage at which it is treated; late infection that has already damaged organs may not fully reverse. Follow-up blood tests, not a single result, confirm the response to treatment.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Early infection missed by blood testing | Window-period dependent | A repeat test may be needed after a recent exposure or if a suspicious ulcer is present. | NHS — Syphilisnhs.ukSource-linked context |
| Treatment cure in early syphilis | High with appropriate penicillin treatment | Follow-up blood titres are needed because cure is judged by response over time, not by symptoms alone. | Guide sourcesClinical context |
| Jarisch-Herxheimer reaction after treatment | Recognised short-term reaction | Fever, aches and worsening symptoms can occur soon after treatment; pregnancy or neurological/eye symptoms need specialist care. | Guide sourcesClinical context |
| Late, neurological, eye or pregnancy complications | Stage-dependent | Delayed diagnosis can affect the brain, eyes, heart or unborn baby, so staging and partner notification matter. | NHS — Syphilisnhs.ukSource-linked context |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
What happens afterwards
There is no physical recovery from the blood test. After treatment, the main things are to avoid sex until the clinic advises it is safe, and to attend follow-up blood tests so the response can be checked over several months.
- No physical after-effects from the blood test
- Short-lived soreness at the injection site
- Flu-like symptoms in the first day after treatment, which then settle
- Feeling relieved, anxious or upset; all are normal reactions
- Attending several follow-up blood tests over the months ahead
Aftercare
- Avoid sex until the clinic confirms it is safe, usually after treatment is complete and any sore has healed.
- Attend all follow-up blood tests so the response to treatment can be tracked.
- Tell recent sexual partners so they can be tested and treated; the clinic can do this anonymously.
- Expect possible flu-like symptoms for a day after treatment; rest and simple painkillers usually help.
- Take any tablet antibiotics exactly as directed and finish the course.
- Tell the clinic straight away about a rash, swelling or breathing difficulty after treatment.
- If you are pregnant, follow the clinic's specific advice closely.
- Consider regular testing and condoms to lower the chance of future infection.
- List of recent sexual partners, if you can, to help notification
- Knowing the dates of your follow-up blood tests
- Any penicillin allergy clearly noted
- A plan to avoid sex until the clinic says it is safe
- The clinic's contact number saved in case of problems
- A reminder to attend in person for the injection(s)
- Awareness that flu-like symptoms for a day after treatment are expected
⚠ Get urgent help if…
- A rash, facial or mouth swelling, or breathing difficulty after the antibiotic (seek urgent help)
- A sore that is not healing, or new sores or rashes
- Severe headache, vision changes, or weakness or numbness in the body
- Chest pain or breathlessness
- High fever that does not settle after the first day following treatment
- In pregnancy, any concern about the baby's movements or your wellbeing
Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your specialist gives you.
Results & realistic expectations
A negative result usually means no syphilis was found, although a blood test taken very soon after exposure can be falsely negative, so a repeat test is sometimes advised. A positive result means syphilis is present; further blood tests help work out the stage and guide treatment.
After treatment, follow-up blood tests are used to confirm the infection is clearing. The level falling over months is the sign treatment has worked. Some blood tests can stay positive for life even after successful treatment, which is why the clinic interprets the results together rather than relying on a single number.
A clear result reflects the time of the test only, and you can catch syphilis again. After successful treatment, some blood tests remain positive permanently, so they cannot simply be repeated to check for reinfection; the clinic interprets changes in specific tests instead. Regular testing is sensible if you have new or multiple partners.
Related tests, treatments or support
Syphilis testing is usually done as part of a full sexual health check that also includes HIV, chlamydia, gonorrhoea and sometimes hepatitis B and C. People diagnosed with syphilis are always offered an HIV test, as the two infections often share the same risks.
Follow-up & long-term care
After treatment, you will have a series of follow-up blood tests over several months to confirm the infection is responding. The clinic will help with partner notification and advise on when, if ever, you can be considered cured. Contact them sooner if new sores, rashes or symptoms appear, or if you are worried after treatment.
- Attend all follow-up blood tests to confirm the treatment has worked.
- Use condoms to lower the risk of future infection.
- Have regular sexual health checks if you have new or multiple partners.
- Make sure partners are tested and treated.
Repeat, follow-on and what comes next
- A repeat blood test is needed if the first was done too soon after exposure.
- Follow-up blood tests over months confirm the response; a result that does not fall as expected may need re-treatment or specialist review.
- Some blood tests stay positive for life after cure, so reinfection is assessed using specific tests rather than a single number.
Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.
What good aftercare looks like
- Injection treatment in clinic with clear advice on when sex is safe again.
- A planned schedule of follow-up blood tests, with a named contact for questions.
- Help with partner notification, anonymously if you prefer.
- Clear written advice on the expected flu-like reaction and when to seek urgent help.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- Whether you use the free NHS service or pay for private testing
- Whether a swab from a sore is needed as well as a blood test
- Whether staging, injection treatment and follow-up blood tests are included
- How quickly results and treatment are provided
- Whether partner notification support is included
- Whether you also test for other infections at the same time
- The cost of the blood test and any swab
- Whether treatment (penicillin injections) is included or arranged if positive
- Whether follow-up blood tests over several months are included
- How and when you will get your result
- Whether partner notification support is provided
- What happens, and what it costs, if the result is positive or staging is needed
On the NHS? Syphilis testing and treatment are free and confidential on the NHS at sexual health (GUM) clinics, and screening is offered in pregnancy; because syphilis needs staging, injection treatment and follow-up blood tests, an in-person service is important and a private test alone is not enough.
You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- No explanation that a too-early blood test can be falsely negative.
- No plan for staging, treatment and the follow-up blood tests that confirm cure.
- Not warning that flu-like symptoms after treatment are expected, which can be mistaken for an allergy.
- Treatment or partner notification not included in a private package.
Marketing red flags
- Selling a single blood test as proof of being clear without explaining window periods or follow-up.
- Charging for testing without explaining that the NHS offers it free and confidentially.
- Implying treatment is a quick fix without follow-up blood tests.
- Not mentioning the importance of an HIV test alongside syphilis testing.
Choosing a specialist safely
- Check the specialist is on the GMC Specialist Register for this area.
- Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
- You're entitled to time to consider and to have your questions answered before you agree — the specialist who looks after you should explain it, not a salesperson.
- Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including any follow-up — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good specialist will welcome every one of these.
- When is the best time to test after the sex I am worried about?
- What stage do you think my infection is, and how many injections will I need?
- What should I expect in the first day after treatment?
- How many follow-up blood tests will I need, and over how long?
- If I am penicillin-allergic, what are my treatment options?
- Can you help me tell my partners anonymously?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the specialist who carries out my treatment, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this treatment not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
Do I have to pay to be tested or treated?
Can syphilis really be cured?
Why might I feel unwell just after treatment?
How soon after sex can I test?
What if I am allergic to penicillin?
Will my follow-up blood test ever go fully negative?
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How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: NHS — Syphilis Terrence Higgins Trust — Syphilis UKMi/NHS — treating syphilis with parenteral benzylpenicillin SH:24 — STI testing window periods
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
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