The singer shocked fans yesterday when he left the world’s biggest band saying he wanted the chance to be “a normal 22-year-old”.
Shortly afterwards pictures emerged on social media from fans who appeared to have harmed themselves and were asking others to do so.
A spokesman for children’s charity Barnardo’s said: “We are horrified at the overnight trending of self-harm tweets after Zayn Malik quit One Direction with teenagers posting pictures of their self-inflicted injuries and encouraging others to follow suit.
“Self-harming sites and social media chat on self-harm are a disturbing aspect of culture which must be addressed and handled sensitively by all those responsible for caring for children.
“Children need a safe place to be able to discuss anything which distresses them and have guidance on how to deal with difficult feelings in a supportive environment.
“Carers, teachers and others and any young person who might be thinking about self-harm are urged to visit the Young Minds website.”
A spokeswoman for Young Minds said: “Zayn is an important role model to other young people, as he is prioritising his wellbeing over fame and taking time out to look after himself.
“Young people who feel affected by this news should reach out to other young people and to trusted adults and talk to them about how they feel. It’s a loss so like any loss it is about taking care of yourself and being with people who care for you and can support you.”
Rachel Burrows, who edits parenting website Netmums. said: “Sadly some youngsters do self-harm to cope with stress, but hashtags like these are dangerous and they can potentially encourage kids to try it.
“The pressures of social media may mean some young fans see it as a way to prove their devotion to Zayn and the band.
“If you think your child is at risk, remind them it isn’t what Zayn or the band would want - they want their fans happy and healthy. You can also contact charities like harmless.org.uk, Mind, the National Self Harm Network or the Netmums Parent Supporters for help.”
The singer left the band’s world tour last week after being “signed off with stress” and returned to the UK after he was forced to defend himself online and declare his love for fiancee Perrie Edwards when pictures emerged of him apparently close to another woman.
The group said they would continue as a four-piece for the tour and record another album - their fifth - later this year.
Yesterday, his former bandmate Harry Styles appeared to break down in tears on stage as he struggled to come to terms with Malik’s sudden departure.
Styles wiped away tears as the band performed the latest leg of their On The Road Again Tour in Jakarta, Indonesia, hours after the news broke.
Pop svengali Simon Cowell, who discovered One Direction on talent show The X Factor, said he was sad to see Malik leave and was “immensely proud” of what he had achieved with the band.
He later tweeted his support for distraught fans, saying: “Sometimes strength is not defined by numbers.”
He added: “As always you the fans have shown your amazing support to all the boys. When you have great talent great things happen.”
Malik’s statement yesterday rocked the pop world and led to a mass outpouring of grief from the band’s young fans.
Among the many parents dealing with the fallout from the news was Radio 5 Live presenter Nicky Campbell’s whose tearful daughter Kirsty joined her dad on air to talk about the “horrible” news.
She told listeners: “Everything’s changed now he’s gone. Like it’s not going to be like One Direction, which is like five of them. It’s just going to be Niall, Louis, Liam, Harry no Zayn... He was part of it and now it’s just horrible that he’s not going to be there any more.”
Many fans took to social media to vent their feelings and were offered words of comfort from a veteran of boyband break-ups: Take That’s Gary Barlow.
Barlow, who saw the disintegration of his own band in 1996 after Robbie Williams left, tweeted: “Sending my best to all the 1D boys ! #thatters we’ve all been there haven’t we ? !!!!!”
Malik appeared in a leaked video last year smoking what appeared to be a joint while the group travelled in a van in South America.
He was also forced to explain his absence from promotional commitments after a US TV host questioned his bandmates about ‘’rumours of substance abuse’’.
The band, who were put together after entering The X Factor as solo acts, have become millionaires on their way to being one of the biggest bands in the world.
Their latest album, Four, topped the US Billboard chart, making them the first group to debut at number one with their first four albums.
They have fans all over the world - their current tour takes in venues in countries including Indonesia and South Africa - and the video for their single, Best Song Ever, attracted almost 200 million views on YouTube.