How STDs Change Vaginal Discharge: Colours, Smell & When to Get Tested

Understanding Vaginal Discharge: What's Normal?

Before exploring how STDs affect vaginal discharge, it's important to understand what's considered normal. Healthy vaginal discharge is your body's way of keeping the vagina clean and maintaining a balanced environment.

Normal Discharge Characteristics

• Colour: Clear to milky white
• Consistency: Varies from thin and watery to thick and sticky, depending on your menstrual cycle
• Odour: Mild or no noticeable smell
• Amount: Varies throughout the month, often increasing around ovulation

Normal discharge changes are influenced by:

• Menstrual cycle phase
• Sexual arousal
• Pregnancy
• Contraceptive use
• Stress levels

When Discharge Changes Become a Concern

While some variation is perfectly normal, certain changes in vaginal discharge may signal an underlying issue, including sexually transmitted infections. Warning signs that warrant attention include:

• Unusual colours: Yellow, green, grey, or brown discharge
• Strong odour: Fishy, foul, or unusually pungent smell
• Texture changes: Frothy, chunky, or cottage cheese-like consistency
• Increased amount: Significantly more discharge than usual
• Accompanying symptoms: Itching, burning, pain during urination or sex

If you notice these changes, it's wise to consider STI testing in London to rule out or identify any infections.

How Common STDs Affect Vaginal Discharge

Different sexually transmitted infections cause distinct changes in discharge. Understanding these patterns can help you recognise potential warning signs – though laboratory testing is always essential for accurate diagnosis.

Chlamydia

Chlamydia is one of the most common bacterial STIs in the UK, particularly among young adults. It's often called "the silent infection" because many people experience no symptoms at all.

How chlamydia affects discharge:

• Increased amount of vaginal discharge
• May appear slightly yellowish or cloudy
• Often has no distinctive odour

Other symptoms to watch for:

• Bleeding between periods or after sex
• Pain during urination
• Lower abdominal or pelvic pain

Important: Up to 70% of women with chlamydia have no symptoms. Left untreated, chlamydia can lead to pelvic inflammatory disease (PID), which may cause chronic pelvic pain, ectopic pregnancy, and infertility. If you're concerned about increased discharge or have had unprotected sex, chlamydia testing is quick and straightforward.

Gonorrhoea

Gonorrhoea is another common bacterial infection that can cause noticeable discharge changes.

How gonorrhoea affects discharge:

• Yellow or green discharge
• Thicker, heavier discharge than normal
• May have an unpleasant odour

Other symptoms:

• Pain or burning when urinating
• Bleeding between periods
• Heavier periods
• Pelvic pain

Like chlamydia, gonorrhoea can be asymptomatic in many women. The characteristic yellow or green discharge with a strong vaginal odour should prompt you to consider a gonorrhoea test. Untreated gonorrhoea also risks PID and fertility complications.

Trichomoniasis

Trichomoniasis is caused by a tiny parasite called *Trichomonas vaginalis*. It's highly treatable but can cause significant discomfort if left undiagnosed.

How trichomoniasis affects discharge:

• Frothy, bubbly discharge
• Yellow-green or grey colour
• Foul-smelling or fishy odour – often the most distinctive feature
• Significantly increased volume

Other symptoms:

• Intense vaginal itching and irritation
• Redness and swelling of the vulva
• Pain during urination or sex
• Discomfort in the lower abdomen

The combination of frothy, foul-smelling discharge with itching is particularly characteristic of trichomoniasis. If these symptoms sound familiar, trichomoniasis testing can provide answers quickly.

Herpes (HSV)

Genital herpes is caused by the herpes simplex virus (HSV-1 or HSV-2). While herpes doesn't typically cause discharge changes directly, it can indirectly affect vaginal discharge.

How herpes may affect discharge:

• Generally doesn't cause abnormal discharge on its own
• During outbreaks, watery discharge may occur
• Secondary bacterial infections from open sores may cause discharge changes

Primary symptoms of herpes:

• Painful blisters or sores on the genitals
• Tingling or burning sensation before outbreak
• Flu-like symptoms during initial infection
• Painful urination if sores are near the urethra

If you're experiencing genital sores or outbreaks alongside any discharge changes, herpes testing can help determine whether HSV is present.

Syphilis

Syphilis is a bacterial infection that progresses through stages if untreated. It doesn't typically cause abnormal vaginal discharge directly, but understanding its symptoms is crucial.

How syphilis relates to discharge:

• Doesn't usually cause direct discharge changes
• Sores (chancres) in the vagina may go unnoticed
• Secondary infections from sores could affect discharge

Primary symptoms:

• Painless sore (chancre) at the infection site
• Rash (often on palms and soles) in secondary stage
• Flu-like symptoms
• Swollen lymph nodes

Syphilis is highly treatable with antibiotics when caught early but can cause serious complications – including damage to the heart, brain, and other organs – if left untreated. A syphilis blood test is recommended if you've had unprotected sex or notice any unusual genital symptoms.

HPV (Human Papillomavirus)

HPV is the most common sexually transmitted infection worldwide. Most strains cause no symptoms, but some can lead to genital warts or cervical cell changes.

How HPV relates to discharge:

• Most HPV infections don't cause discharge changes
• Genital warts (caused by low-risk HPV strains) don't typically affect discharge
• High-risk HPV strains may eventually cause cervical changes detectable through screening

When HPV becomes a concern:

• Visible warts on the genitals
• Abnormal cervical screening results
• Increased cancer risk with persistent high-risk strains

Regular cervical screening (smear tests) is essential for detecting HPV-related cell changes. If you have concerns about genital warts or your HPV status, HPV testing or cervical screening can provide clarity.

Hepatitis B

Hepatitis B is a viral infection affecting the liver. While it doesn't directly cause vaginal discharge changes, it's an important STI to understand.

How hepatitis B relates to discharge:

• Doesn't cause vaginal discharge changes directly
• May weaken the immune system, potentially affecting the vaginal environment indirectly

Symptoms of hepatitis B:

• Fatigue
• Nausea and vomiting
• Abdominal pain
• Jaundice (yellowing of skin and eyes)
• Dark urine
• Many people have no symptoms initially

If you're experiencing systemic symptoms alongside any discharge changes, comprehensive screening including hepatitis B testing may be appropriate.

HIV

HIV attacks the immune system and, if untreated, can lead to AIDS. While HIV itself doesn't cause discharge changes, it creates vulnerability to secondary infections.

How HIV may indirectly affect discharge:

• Weakened immune system increases susceptibility to:
• Yeast infections (thrush)
• Bacterial vaginosis
• Other opportunistic infections
• These secondary infections can cause abnormal discharge

Symptoms of HIV:

• Initial flu-like illness 2-4 weeks after infection
• Often asymptomatic for years
• Recurrent infections as immune system weakens

If you're experiencing recurrent vaginal infections causing discharge changes, alongside other symptoms or risk factors, HIV testing should be considered as part of comprehensive sexual health screening.

STDs vs Non-STD Conditions: Understanding the Difference

Not all discharge changes indicate an STI. Several non-sexually transmitted conditions can cause similar symptoms:

Bacterial Vaginosis (BV)

BV is the most common cause of abnormal vaginal discharge in women of reproductive age. It occurs when the natural balance of bacteria in the vagina is disrupted.

BV discharge characteristics:

• Thin, grey or white discharge
• Strong fishy odour, especially after sex
• May be accompanied by mild itching

BV is NOT an STI – it's caused by an imbalance of natural vaginal bacteria. However, it can occur alongside STIs, and having BV may increase your risk of acquiring STIs. If you're unsure whether symptoms are BV or an STI, a full STI screening can help clarify the diagnosis.

Yeast Infections (Thrush)

Vaginal thrush is caused by an overgrowth of *Candida* yeast, which naturally exists in small amounts in the vagina.

Thrush discharge characteristics:

• Thick, white, cottage cheese-like discharge
• Usually odourless or yeasty smell
• Intense itching and irritation
• Redness and swelling

Thrush is NOT an STI – it's caused by yeast overgrowth, often triggered by antibiotics, hormonal changes, or a weakened immune system. However, its symptoms can overlap with some STIs, making testing worthwhile if you're uncertain.

When to Rule Out STIs

If you have discharge changes along with:

• A new sexual partner
• Unprotected sex
• A partner with known or suspected STI
• Multiple sexual partners

...then STI testing should be a priority, even if symptoms seem more consistent with BV or thrush.

Why Many STIs Remain Silent

One of the most challenging aspects of sexually transmitted infections is that many cause no symptoms at all – or symptoms so mild they go unnoticed.

Asymptomatic STI Statistics

• Chlamydia: Up to 70% of women have no symptoms
• Gonorrhoea: Up to 50% of women are asymptomatic
• Trichomoniasis: About 70% of infected people have no symptoms
• Herpes: Up to 80% of people with genital herpes don't know they have it
• HIV: Can remain asymptomatic for years

This means you could have an STI causing internal damage – potentially leading to PID, infertility, or other complications – without any discharge changes or other obvious signs.

The takeaway: Don't rely on symptoms alone to determine your STI status. Regular testing is the only reliable way to know.

When to Get Tested for STIs

Immediate Testing Recommended If You Have:

• Abnormal vaginal discharge (colour, odour, or consistency changes)
• Strong vaginal odour that's new or unusual
• Genital sores, blisters, or warts
• Pain during urination or sex
• Unusual bleeding between periods or after sex
• A partner who has tested positive for an STI

Routine Testing Recommended If:

• You have a new sexual partner
• You have multiple sexual partners
• You've had unprotected sex
• You're starting a new relationship and planning to stop using condoms
• It's been more than a year since your last STI test
• You're pregnant or planning pregnancy

Testing Frequency Guidelines

• Every 3-6 months: If you have multiple partners or are at higher risk
• Annually: If you're sexually active with changing partners
• After every new partner: Especially before stopping condom use
• If symptoms develop: Don't wait – get tested promptly

What to Expect from STI Testing

Modern STI testing in London is straightforward, confidential, and often much simpler than people expect.

Common Test Types

• Urine sample: For chlamydia and gonorrhoea
• Vaginal swab: For various infections including trichomoniasis
• Blood test: For HIV, syphilis, hepatitis B and C
• Visual examination: For genital warts and herpes sores

Test Turnaround Times

Most results are available within 1-3 days, with some rapid tests offering same-day results.

Comprehensive Screening Options

For peace of mind, comprehensive screening packages test for multiple infections at once. Our compare packages page can help you choose the right level of testing for your needs.

Treatment and Next Steps

The good news: most STIs are highly treatable, especially when caught early.

Bacterial Infections (Chlamydia, Gonorrhoea, Syphilis, Trichomoniasis)

• Treated with antibiotics
• Usually cleared with a single course of treatment
• Partners should also be tested and treated
• Follow-up testing recommended to confirm cure

Viral Infections (Herpes, HPV, HIV, Hepatitis B)

• Can be managed but not cured
• Antiviral medications control symptoms and reduce transmission
• Regular monitoring and management
• Highly effective treatments available (especially for HIV)

The Importance of Partner Notification

If you test positive for an STI, it's important that recent sexual partners are informed so they can also get tested and treated. This helps prevent reinfection and protects their health.

Take Control of Your Sexual Health

Changes in vaginal discharge can understandably cause concern, but knowledge and action are your best defences. Whether your symptoms turn out to be an STI, bacterial vaginosis, thrush, or simply normal variation – getting tested provides clarity and peace of mind.

Key Takeaways

• Normal discharge varies throughout your cycle – not all changes indicate a problem
• STIs can cause distinctive discharge changes – yellow/green colour, fishy odour, frothy texture
• Many STIs are asymptomatic – regular testing is essential regardless of symptoms
• Non-STI conditions like BV and thrush can mimic STI symptoms
• Early detection and treatment prevent complications and protect partners

Ready to Get Tested?

Don't let worry or uncertainty hold you back. Our private sexual health clinic offers confidential, non-judgemental testing with fast, accurate results. Whether you need a single test or comprehensive screening, we're here to support your sexual health.

Book your confidential STI test today and take the first step towards peace of mind.

Frequently Asked Questions

What colour discharge indicates an STD?

Yellow, green, or grey discharge can indicate an STI, particularly gonorrhoea (yellow-green) or trichomoniasis (yellow-green, frothy). However, colour alone isn't diagnostic – testing is essential for accurate identification.

Can an STD cause smelly discharge?

Yes. Trichomoniasis and bacterial vaginosis (which isn't an STI but can occur alongside STIs) commonly cause a strong fishy odour. Gonorrhoea may also cause an unpleasant smell.

Why does my discharge smell but I have no STD?

Bacterial vaginosis is the most common cause of fishy-smelling discharge and isn't sexually transmitted. Yeast infections, hormonal changes, and hygiene practices can also affect vaginal odour. If you're unsure, testing can rule out STIs.

How long after exposure do STI discharge symptoms appear?

This varies by infection: chlamydia and gonorrhoea symptoms may appear within 1-3 weeks; trichomoniasis within 5-28 days. However, many STIs remain asymptomatic, so testing is recommended 2-3 weeks after potential exposure.

Should I get tested if my discharge changed but I'm in a monogamous relationship?

Yes, testing is still worthwhile. Some STIs can remain dormant for months or years before causing symptoms. Additionally, your symptoms might indicate a non-STI condition that also requires treatment.

Where can I get confidential STI testing in London?

Our confidential STI clinic offers discreet testing with professional support. We provide individual tests and comprehensive screening packages, with most results available within 1-3 days.