Sitting in A&E aged just 19 and in her second year of university with agonising, swollen ankles – the latest in a long line of unexplained health complaints – it dawned on Rachel Hall how unwell she was.

The doctor was saying her latest problem was nothing serious, as her partner, now husband, Leon, reeled off the long list of symptoms she had been struggling with for months.

‘Leon described how I had lost weight and my hair was falling out,’ says Rachel, from Lewisham, south-east London.

‘I had ongoing urine infections, thrush, a rash all over my body, abscesses under my arms and my mouth was full of ulcers.

‘I had aching, swollen joints in my legs, feet, hands and arms.

‘I slept constantly, but was always completely exhausted. And it just dawned on me, I am constantly sick. What could be making me this ill?’

It would take another year – during which she visited her doctor or A&E more than a dozen times – for Rachel to get the answer: she has systemic lupus erythematosus, better known as lupus.

This is a condition in which the immune system misfires and attacks the body’s own cells.

Normally when cells die they are cleared from the blood by scavenger cells, called macrophages. But in lupus, this process does not work properly, and fragments of the old cells are left in the bloodstream.

These fragments are picked up by immune cells, which mistake them for invaders, triggering the production of antibodies that attach themselves to the patient’s cells and tissues, leading to inflammation and damage.

Around 40,000 people in the UK have the condition; 90 per cent of them women, for reasons that are not fully understood.

‘It can be very difficult to live with,’ says Professor Christopher Edwards, a consultant rheumatologist at University Hospital Southampton NHS Foundation Trust, who also works in lupus research.

‘Patients experience fatigue, pain and brain fog, which are very disruptive to everyday life.’

Almost any part of the body can be affected, from the joints – leading to painful arthritis – to a distinctive ‘butterfly’ rash which spreads, itchy and red, across the cheeks and the bridge of the nose.

Lupus can also damage the kidneys, lungs, heart, brain, nervous system and muscles.

Some patients also suffer from painful mouth ulcers, as the immune system attacks the delicate lining of the mouth, or hair loss.

The problem is that these symptoms are often mistaken for other complaints, from eczema (because of the red rash) to cancer.

‘Lupus is a great mimic and the symptoms can look like many other conditions, which can be very confusing,’ says David Isenberg, a lupus researcher and emeritus professor of rheumatology at University College London.

‘As it can cause a fever, people will be investigated for infection.

‘And I get patients referred to me from clinics for cancer, and those who have been misdiagnosed with rheumatoid arthritis, for instance.’

One reason for the confusion is that lupus is diagnosed through a combination of the patient’s medical history and blood tests to detect specific antibodies. But these aren’t always accurate, as not everyone with lupus will test positive, and other autoimmune conditions, such as rheumatoid arthritis, may also lead to a positive result.

Exactly what triggers lupus is unknown; it seems to be down to a combination of genes (people with Black-African or Asian backgrounds are more at risk); hormones; and external factors such as viruses and exposure to the sun (UV light speeds up the death of cells, which may lead to the misfiring immune system).

A study published earlier this year in the journal Arthritis & Rheumatology suggested that exposure to airborne pollution increases the risk of lupus. The outlook for people with lupus has improved dramatically thanks to better treatments.

The chances of surviving four years after diagnosis was only 50 per cent in the 1950s. Now, about 85 per cent of people live 15 years after diagnosis.

Yet despite such advances, Professor Isenberg points out someone diagnosed at 20 still has around a one in seven chance of not living to 35.

‘You can see how it continues to be a very worrying condition,’ he says.

Rachel, now 35 and living with Leon, 37, an electrician, and their daughter Naomi, two, is proof that treatments have improved, though there is still no cure.

Her condition is maintained by a cocktail of 12 daily drugs – and she recently benefitted from taking part in a new drug trial.

Most people with lupus will start their treatment with steroids and/or the drug hydrochloroquine, to reduce inflammation and swelling.

If this does not work, other drugs can be prescribed to dampen down the immune system response, including disease-modifying anti-rheumatic drugs and newer therapies called ‘biologics’.

Biologics, such as belimumab and rituximab, bind to a type of white blood cell (B-cell) that produces the antibodies which can trigger the effects seen in lupus.

But all these treatments come with potential side-effects.

Long-term steroid use can thin the bones, cause diabetes and lead to high blood pressure, by making the body retain more water. And like many immune-suppressing drugs, can leave patients vulnerable to infections.

Lifestyle changes such as giving up smoking (which stimulates the immune system) and eating a Mediterranean-style diet rich in fruit, vegetables and oily fish may be suggested to help reduce inflammation.

But major changes may be on the horizon.

Earlier this year, a study published in the New England Journal of Medicine found that CAR T-cell therapy – a cutting-edge cancer treatment – seems to also reduce lupus symptoms.

CAR T-cell therapy works by removing and genetically tweaking a type of white blood cell called a T-cell.

After chemotherapy to destroy the malfunctioning immune cells, the patient receives an infusion of their new tweaked T-cells which then identify and destroy the malfunctioning B-cells that cause lupus.

After the initial treatment patients seem able to make a healthy B-cells themselves.

Eight patients with severe lupus given CAR T-cell therapy went into full remission and stayed there until the end of the study, two years later, without needing to go back on to immune-suppressing lupus medication.

Professor Isenberg says the results are ‘quite sensational’ and ‘a real game-changer’.

The downside is the cost – around £300,000 per patient – and the treatment requires a two-week hospital stay, meaning it is likely to be offered only to the most severe cases, says Professor Isenberg.

Trials are now beginning in the UK.

In Rachel’s case, at the time of her diagnosis aged 21 she had become so ill she’d had to drop out of university. After ten months of treatment with steroids and hydrochloroquine to reduce the immune response and inflammation, she felt able to return to university and completed her degree.

She was able to start a successful career as a community liaison manager with a property development company, but there have been highs and lows. She often needed painkillers for her hands ‘because they were so swollen’, she says.

Since then Rachel has been tried on biologics, daily tablets of a stronger immuno-suppressant, mycophenolate mofetil – and even at one point cyclophosphamide, a powerful immunosuppressant used in chemotherapy.

Off work for five months, it was, she recalls ‘a really horrible time’.

She also worried her illness might mean she missed her chance of motherhood. However, after finishing the chemotherapy in early 2019, Rachel enrolled on a trial to receive two biologics – rituximab mixed with belimumab – which put her into remission.

She went on to have a carefully monitored pregnancy: her daughter Naomi was born in 2021.

Another major flare-up, in 2022, led her to retrain as a career coach. Now she takes life a day at a time.

‘My husband and family have been incredible throughout,’ Rachel says. ‘I have needed a lot of help as I often couldn’t lift Naomi, do bath time or always go out.’

Her hands remain very swollen, she sometimes struggles to walk and she’s also lost 11 teeth (the lupus attacked her gums), so now wears dentures.

The 12 tablets a day she takes, including tacrolimus, an immunosuppressant.

Living with uncertainty and ‘a lot of pain’ is hard, she admits.

‘But I’m a positive person and I take hope from having spells where I feel a lot better, and new treatments being developed.

‘I never thought I’d have children and yet I have a beautiful daughter.

‘Soon I will have had lupus for half my life, and a lot of good things have happened in that time.’