Using some public loos could put you at risk of contracting viruses, one UK doctor has warned. 

Small, red marks found on toilet tissue could be specs of blood soiled by intravenous drug users cleaning their needles. 

The needles, used for injecting illegal drugs, often contain blood which may be infected with pathogens including hepatitis B, C or HIV. 

One London-based doctor has warned that this is a 'possible' risk, albeit a 'very rare' one. 

Dr Sermed Mezher, a locum GP who boasts over 200,000 TikTok followers, claimed: 'People have said the risk of transmission from using one of these is one in three for hepatitis and one in 300 for HIV. 

'But that's for healthcare workers who get direct impact when the blood is still wet. 

'The risk of transmission if something has dried up like this is significantly lower but it's still possible.'

Experts have long warned that intravenous drug users may sometimes resort to using makeshift cleaning methods for their needles, such as wiping them with toilet paper or other available materials. 

But the method is ineffective in properly sterilizing the needle as wiping the needle with toilet paper does not remove or kill these viruses. 

Instead, they may remain on the needle or expose people to indirect exposure by transferring to surfaces like sinks, toilet seats, or dispensers.

Dr Mezher added: 'Of course it's also incredibly rare that a drug user would want to do this, as they would be blunting their needle. 

'There are also needle exchange programmes which can help them get clean ones for free. 

'These drug rehabilitation programmes are important not just to protect others but also ourselves as well.'

Other experts have cautioned that the risk of contracting HIV from toilet paper is virtually impossible. 

Once outside the body, HIV 'usually can’t survive for very long', the Terrence Higgins Trust advises. 

'Coming into contact with blood or semen that has been outside the body doesn’t generally pose a risk for HIV transmission,' the charity notes. 

In another TikTok video, Harm Reduction Services — a California-based nonprofit organization — also warned it was unlikely toilet paper would be used to clean needles, given 'needles dull very quickly. 

They added: 'If someone is cleaning needles to reuse them ... they're going to do it with a liquid, like a bleach solution, so it doesn't dull the tip.'

However, according to the World Health Organization (WHO) hepatitis is 50 to 100 times more infectious than HIV. 

Hepatitis B virus can also survive outside the body for at least 7 days, the UN agency says. 

It's estimated that there are 105,200 people living with HIV in the UK, according to National AIDS Trust.

But only 94 per cent of these people are diagnosed.

This means that around 1 in 16 people living with HIV in the UK do not know that they have the virus.

Treatment options have evolved considerably since HIV was first identified in the early 80s, with patients now taking daily medication — anti-retroviral therapies — to tamp down the amount of virus in the blood to undetectable levels.  

However, while these medications are effective, they are not a cure.

This has eluded scientists for decades because of the unique way in which the virus hijacks the body's own cells.

HIV hides in immune cells in the body, where the viral cells can shield themselves from being destroyed. 

This makes hunting and killing HIV in the body difficult, because there is a risk of damaging healthy cells as well.

Hepatitis, of which there are multiple types, often has no noticeable symptoms.

But signs of the infection include dark urine, pale grey-coloured faeces, itchy skin and the yellowing of the eyes and skin.

Infected people can also suffer muscle and joint pain, a high temperature, feeling and being sick and being unusually tired all of the time, according to the NHS.

Experts warn, however, that living with hepatitis B 'often subjects people to stigma meaning fewer people come forwards for potentially life-saving treatments'.

The NHS is set to eliminate another type of hepatitis, hepatitis C (hep C) by 2025 – five years ahead of the WHO's target.

Deaths from hep C in England have fallen by 35 per cent in six years, well-exceeding the target of 10 per cent. They are also at their lowest level in 20 years.