A mother in northern Nigeria is visibly upset as she clutches her two-year-old child, who has burns and discoloured skin on his face and legs.

The 32-year-old used skin-whitening products on all six of her children, under pressure from her family, with results that she now deeply regrets.

Fatima, whose name has been changed to protect her family's identity, says one of her daughters covers her face whenever she goes out in order to hide her burns.

Another was left with darker skin than before - with a pale circle around her eyes, while a third has whitish scars on her lips and knees.

Her toddler still has weeping wounds - his skin is taking a long time to heal.

"My sister gave birth to light-skinned children but my children are darker skinned. I noticed that my mother favours my sister's children over mine due to their skin tone and it hurt my feelings a lot," Fatima says.

She says she used creams she bought at her local supermarket in the city of Kano, without a doctor's prescription.

At first it seemed to work. The grandmother warmed towards Fatima's children, who were aged between two and 16 at the time.

But then the burns and scars appeared.

Skin-whitening or lightening, also known as bleaching in Nigeria, is used in different parts of the world for cosmetic reasons, though these often have deep cultural roots.

Women in Nigeria use skin-whitening products more than in any other African country - 77% use them regularly, according to the UN World Health Organization (WHO).

In Congo-Brazzaville the figure is 66%, in Senegal 50% and in Ghana 39%.

The creams may contain corticosteroids or hydroquinone, which can be harmful if used in high quantities, and in many countries are only obtainable with a doctor's prescription.

Other ingredients sometimes used are the poisonous metal, mercury, and kojic acid - a by-product from the manufacture of the Japanese alcoholic drink, sake.

Dermatitis, acne and skin discolouration are possible consequences, but also inflammatory disorders, mercury poisoning and kidney damage.

The skin may become thinner, with the result that wounds take longer to heal, and are more likely to become infected, the WHO says.

The situation is so bad that Nigeria's National Agency for Food and Drug Administration and Control (Nafdac) declared a state of emergency in 2023.

It is also becoming more common for women to bleach their children, like Fatima did.

"A lot of people link light skin to beauty or wealth. Women tend to shield, as they call it, their children from that discrimination by bleaching them from childbirth," Zainab Bashir Yau, the owner of a dermatology spa in the capital, Abuja, tells the BBC.

She estimates that 80% of the women she has met have bleached their children, or plan to do so.

Some were bleached themselves as babies, she says, so are just continuing the practice.

One of the most common ways to tell whether someone is using skin-whitening products in Nigeria is by the darkness of their knuckles. Other parts of people's hands or feet get lighter, but knuckles tend to remain dark.

However, smokers and drug users also sometimes have dark patches on their hands, due to the smoke.

So users of skin-lightening products are sometimes mistakenly assumed to belong to this group.

Fatima says that is what happened to her daughters, aged 16 and 14.

"They faced discrimination from society - they all point fingers at them and call them drug addicts. This has affected them a lot," she says.

They have both lost potential fiancés because men do not want to be associated with women who might be thought to take drugs.

I visited a popular market in Kano, where people who call themselves "mixologists" create skin-whitening creams from scratch.

The market has a whole row of shops where thousands of these creams are sold.

Some pre-mixed varieties are arranged on shelves, but customers can also select raw ingredients and ask for the cream to be mixed in front of them.

I noticed that many bleaching creams, with labels saying they were for babies, contained regulated substances.

Other sellers admitted using regulated ingredients such as kojic acid, hydroquinone and a powerful antioxidant, glutathione, which may cause rashes and other side-effects.

I also witnessed teenage girls buying bleaching creams for themselves and in bulk so that they could sell them to their peers.

One woman, who had discoloured hands, insisted that a seller add a lightening agent to a cream that was being mixed for her children, even though it was a regulated substance for adults and illegal to use on children.

"Even though my hands are discoloured, I am here to buy creams for my kids so they can be light-skinned. I believe my hands are this way just because I used the wrong one. Nothing will happen to my children," she said.

One seller said most of his customers were buying creams to make their babies "glow", or to look "radiant and shiny".

Most seemed to be unaware of the approved dosages.

One salesman said he used "a lot of kojic" - well over the prescribed limit - if someone wanted light skin and a smaller quantity if they wanted a subtler change.

The approved dosage of kojic acid in creams in Nigeria is 1%, according to Nafdac.

I even saw salesmen giving women injections.

Dr Leonard Omokpariola, a director at Nafdac, says attempts are being made to educate people about the risks.

He also says markets are being raided, and there are efforts to seize skin-lightening ingredients at Nigeria's borders as they are brought into the country.

But he says it was sometimes hard for law-enforcement officials to identify these substances.

"Some of them are just being transported in unlabelled containers, so if you do not take them to the labs for evaluation, you can't tell what is inside."

Fatima says her actions will haunt her forever, especially if her children's scars do not fade.

"When I confided in my mum about what I did, due to her behaviour, and when she heard the dangers of the cream and what stigma her grandchildren are facing, she was sad that they had to go through that and apologised," she says.

Fatima is determined to help other parents avoid making the same mistake.

"Even though I have stopped... the side-effects are still here, I beg other parents to use my situation as an example."