STIs and STDs – what’s the difference?

Reviewed by our clinical team

In the past ten years, we’ve seen the English language undergo a huge number of changes. From the ubiquity of new words like ‘app’, ‘hashtag’ and ‘Brexit’ to the changing definition of existing words such as ‘literally’, it’s been a busy decade for Anglophones. One of the more subtle switches has taken place in the medical community, where doctors have begun to abandon the term ‘STD’ in favour of ‘STI’.

The question is, why? And what’s the real difference between the two?

Sexually transmitted infections vs sexually transmitted diseases

The first thing to understand is that STI stands for ‘sexually transmitted infection’ and STD stands for ‘sexually transmitted disease’. At first glance, these two phrases may appear almost identical – and indeed, many medical institutions and professionals use the terms interchangeably.

Think on it for a moment, though, and you’ll realise that ‘infection’ and ‘disease’ connote different things. In the medical community, an infection is defined as the invasion of the body by bacteria, viruses or parasites. While an infection can cause symptoms and complications, altering the normal function of the body, it does not depend upon this by definition. A disease, by contrast, causes specific health complications.

Simply put, a sexually transmitted infection is the broader term – and an STI on its own is not necessarily something that will develop into a disease. You may carry the infection, and even be contagious, but it may never lead to any symptoms or cause you real health problems.

Of the two terms, this makes STI slightly less definitive; it’s also a phrasing that certain medical professionals hope will create less of a stigma around sex-related conditions. It’s likely that this is the reason why you will no longer find the term ‘STD’ used on sites like the NHS or the FPA (Family Planning Association).

Ultimately, you shouldn’t exhaust yourself trying to understand the very subtle difference between these terms. What is important is getting to grips with the symptoms of sexually transmitted infections and diseases, and learning how to best protect yourself.

STIs and STDs: the key facts

A report from Public Health England indicated that the most common STI/STD in the country is chlamydia, followed by genital warts, non-specific genital infections, and gonorrhoea (non-specific genital infection refers to a condition such as urethritis, in which the urethra becomes inflamed by bacteria). Other STIs to be aware of are genital herpes, syphilis and HIV.

Some of these infections/diseases are bacterial which means they can usually be cured with a course of antibiotics. Others are viral which means their symptoms can be managed – usually with antiviral medication – but they are harder to permanently eradicate.

Common Symptoms of STIs and STDs

No two STIs or STDs are the same, but some have very similar symptoms. Common symptoms to watch out for include:

• Unusual discharge from the vagina or penis
• Pain while urinating
• Painful blisters around the genitals
• Fleshy growths around the genitals
• Tingling or itching around the genitals
• In men, pain in the testicles
• In women, pain in the pelvis or abdomen
• In women, irregular periods or bleeding after sex

Two infections which have slightly more unusual symptoms are syphilis and HIV. The primary symptoms of syphilis can include one or more painless sores on the genitals, a rash and flu-like symptoms. The primary symptoms of HIV can include flu-like symptoms and a red rash across the body.

Pubic lice and scabies, while not STIs or STDs in the strictest sense, are commonly spread through sexual contact and can cause genital itching, a rash, spots of blood on your genitals, and black spots in your underwear.

It’s also very important to understand that not all STIs and STDs initially present with symptoms – in fact up to 70% of women don’t experience symptoms when infected with chlamydia. For that reason, you should get tested after any episodes of unprotected sex, even if you’re asymptomatic.

Staying safe and getting tested

To stay safe during sex you should:

• Use condoms/dental dams when you aren’t sure your partner is STI-free
• Be aware that you can contract STIs through oral sex and anal sex
• Avoid sharing sex toys
• Get tested

It’s easier now than it’s ever been to get tested for sexually transmitted infections and diseases. You can get tested for free at NHS centres including your local GP surgery and sexual health clinic. You can also send off for our home test kits, taking a sample yourself and sending it back to be screened.

Just remember: the longer you wait to get tested, the more you risk serious complications – when left untreated, a mild case of chlamydia can end up threatening your fertility.

Find out more about our STI test kits and STI treatments. 

References

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/559993
https://www.nhs.uk/conditions/chlamydia/symptoms/