Understanding FND.

An autoimmune disease is one where the immune system — the part of you that is meant to fight infection — mistakenly identifies your own tissue as the enemy and attacks it. Depending on which tissue it targets, you get a different diagnosis: glands, blood vessels, joints, skin, kidneys, lungs, the nervous system.

It is entirely possible to have several at once. Overlapping autoimmune conditions are common, and each one adds its own symptoms and its own risks. On top of that, many of us have persistently low white blood cell counts — the very cells that fight infection — either from the disease itself or from the medication used to calm it down. That is why an ordinary flu is not ordinary for me.

Sjögren's is an autoimmune condition that attacks the moisture-producing glands — mainly the tear glands and the salivary glands. The classic symptoms are severe dry eyes (gritty, burning, light-sensitive) and dry mouth, which brings difficulty swallowing, dental decay and mouth infections.

It is far more than dryness, though. Sjögren's causes profound fatigue, joint and muscle pain, dry skin, vaginal dryness, and it can involve the kidneys, lungs, liver and nerves. It is diagnosed through blood antibodies (anti-Ro/SSA and anti-La/SSB), tear-flow tests and sometimes a lip gland biopsy. Treatment manages symptoms — artificial tears and saliva, hydroxychloroquine, and careful dental care.

APS, sometimes called Hughes syndrome or 'sticky blood', is an autoimmune clotting disorder. The immune system makes antibodies against phospholipid-binding proteins in the blood, which makes the blood far more likely to clot than it should.

That means a raised risk of deep vein thrombosis, pulmonary embolism, stroke and heart attack, often at a young age. It is also one of the leading treatable causes of recurrent miscarriage and pregnancy loss, because clots form in the tiny vessels of the placenta. Other signs include migraines, a lacy purple mottling of the skin called livedo reticularis, and low platelets.

It is diagnosed with blood tests (lupus anticoagulant, anticardiolipin and anti-beta-2-glycoprotein I antibodies) repeated at least twelve weeks apart. Treatment is anticoagulation — low-dose aspirin, heparin, or warfarin — for life in most people who have already clotted.

Lupus is a systemic autoimmune disease that can inflame almost any organ: skin, joints, kidneys, heart, lungs, blood cells and brain. It runs in flares and remissions, so you can look well one week and be floored the next.

Common features are the butterfly rash across the cheeks and nose, photosensitivity, mouth ulcers, joint pain and swelling, hair loss, fevers, pleurisy, kidney inflammation (lupus nephritis), and low blood counts — including low white cells, which is one of the diagnostic criteria and one of the reasons infection is genuinely dangerous.

Diagnosis rests on the pattern of symptoms plus blood tests: ANA, anti-dsDNA, anti-Smith, complement levels, kidney function and urine testing. Treatment usually includes hydroxychloroquine, steroids during flares, and immunosuppressants — which lower immunity further, a permanent trade-off.

Scleroderma means 'hard skin'. It is an autoimmune connective-tissue disease in which the body overproduces collagen, so tissue thickens, tightens and scars. Localised scleroderma affects patches of skin; systemic sclerosis affects internal organs as well.

Typical features are tight, shiny, hardened skin (often starting on the fingers and face), Raynaud's phenomenon where fingers turn white then blue in the cold, painful digital ulcers, joint contractures, reflux and swallowing problems as the oesophagus stiffens, slowed gut motility, lung fibrosis and pulmonary hypertension.

Diagnosis uses examination, antibodies (anti-centromere, anti-Scl-70/topoisomerase, anti-RNA polymerase III), nailfold capillaroscopy, lung function tests and imaging. There is no cure; treatment targets each organ — vasodilators for Raynaud's, proton-pump inhibitors for reflux, immunosuppressants for lung involvement.

Drug-induced liver injury (DILI) happens when medication damages liver cells. It can be dose-related and predictable, or idiosyncratic — an unpredictable reaction in a susceptible person. When the damage is severe or sustained enough, liver function fails: the organ can no longer clear toxins, make clotting factors and albumin, or metabolise medication properly.

Signs include jaundice, dark urine, pale stools, itching, nausea, right-sided abdominal pain, easy bruising and bleeding, fluid in the abdomen, and confusion (hepatic encephalopathy) in advanced cases. Blood tests show raised ALT, AST, ALP and bilirubin, and a prolonged INR when synthetic function drops.

The practical consequence is enormous: almost every drug is processed by the liver, so a failing liver narrows the list of things I can safely take to almost nothing. Most antibiotics, paracetamol at normal doses, many antifungals, statins and standard painkillers become risky or off-limits. Alcohol is out entirely. Treatment is withdrawal of the offending drug, supportive care, and monitoring — the liver can regenerate, but only if it is not hit again.

Put them together and it is a molotov cocktail. The autoimmune conditions and their treatments keep my white blood cells low, so an infection that most people shrug off can take hold and spread. Scleroderma and lupus can both involve the lungs, so a chest infection has less reserve to work with. APS raises clotting risk, and infection and immobility raise it further. Liver failure removes most of the medicines that would normally treat any of this — antibiotics included. And FND amplifies everything: fever, dehydration and exhaustion are classic triggers for a symptom flare or functional seizures.

This is why staying home is not antisocial and not paranoia. It is infection control. If you love someone in this position, the kindest thing you can do is not visit while you are ill.

Red flags that mean go in, no arguing: breathlessness at rest, chest pain, blue lips, a fever that will not come down, coughing up blood, confusion, not being able to keep fluids down, or a new one-sided leg swelling. None of this is medical advice — it is my own experience alongside my specialists.