Rheumatoid Arthritis: Causes, Symptoms, Diagnosis and How Leflunomide Treatment Works

Rheumatoid arthritis is not wear and tear. The immune system attacks the lining of the joints, the synovium, and keeps attacking it. That lining thickens, floods the joint with inflammatory cells and begins to eat into cartilage and bone. Left alone, the damage is permanent; caught early and treated properly, most people now avoid deformity altogether.

The difference between those two outcomes is mostly a matter of months. Rheumatologists talk about a window of opportunity in roughly the first twelve weeks of symptoms, when treatment changes the long-term course far more than the same treatment started a year later. That is why persistent joint swelling is one of the few symptoms worth pushing for a fast appointment.

🔍 How rheumatoid arthritis announces itself

The classic opening is symmetrical: the same knuckles on both hands, the same joints in both feet. Swelling is soft and boggy rather than bony. And the stiffness has a specific signature.

Fatigue deserves its own mention. Many people describe it as the worst part of the disease, worse than the pain, and it often arrives before the joints do. Low-grade fever, loss of appetite and unexplained weight loss belong to the same systemic picture.

🧬 Why the immune system turns on the joints

No single cause explains rheumatoid arthritis. Genes load the gun and environment pulls the trigger.

Genetics

A group of HLA-DRB1 variants known as the shared epitope raises risk substantially. Having an affected first-degree relative roughly triples it. Genes alone are not enough, which is why identical twins are often discordant.

Smoking

The strongest modifiable risk factor by a wide margin, and the worst offender in people who carry the shared epitope. It also makes established disease more severe and makes medicines work less well.

Sex and age

Women are affected about three times more often than men, most commonly starting between 30 and 60.

Gum disease

A consistent association exists with periodontitis, one theory being that certain oral bacteria modify proteins in a way the immune system later attacks.

Body weight

Obesity raises risk modestly and reduces the chance of reaching remission.

🩸 Diagnosis: the tests that matter

There is no single test that says yes or no. Diagnosis combines the joint examination, blood work and imaging.

• 🧪 Anti-CCP antibodies — the most useful test. Highly specific for rheumatoid arthritis and often positive years before the first swollen joint. A positive result also predicts a more aggressive course
• 🧪 Rheumatoid factor — older and less specific. It turns up in hepatitis C, Sjogren syndrome and in healthy older people, so a positive result on its own proves nothing
• 📈 CRP and ESR — measure how much inflammation is present now and are used to track response to treatment
• 🩻 X-rays — show erosions, but usually only once damage has happened
• 🔊 Ultrasound or MRI — pick up synovitis and early erosions long before an X-ray does

🎯 Treat to target: the strategy behind modern care

Care is no longer a matter of taking something and hoping. The approach used since the ACR and EULAR guidance of the last decade sets a numeric goal and chases it.

1. Start a DMARD within weeks of diagnosis, not after a trial of painkillers
2. Measure disease activity with a score such as DAS28, which combines swollen joints, tender joints, a blood marker and the patient rating
3. Review every one to three months while the disease is active
4. Change treatment if the target is not met within three to six months, rather than waiting a year to see
5. Aim for remission, or low disease activity in people with long-standing disease

The target itself is what makes the difference. Trials comparing tight control against routine care found better joint outcomes with the same medicines, simply because doses were escalated sooner.

💊 The treatment classes explained

🧪 Leflunomide in practice

Leflunomide, sold as Arava (Leflunomide) and as the generic Lefuheal (Leflunomide), blocks an enzyme called dihydroorotate dehydrogenase. Activated lymphocytes need that enzyme to build pyrimidines and multiply; without it, the immune attack loses its supply line. In head-to-head trials it performs about as well as methotrexate, which makes it the usual choice when methotrexate is not tolerated, not effective enough, or ruled out by lung or liver problems.

📏 Dose and timing

• 💊 Usual maintenance dose is 10 mg or 20 mg once daily, with or without food
• ⏳ A loading dose of 100 mg daily for three days is no longer routine, because it increases side effects without speeding up the benefit much
• 📅 Do not expect a fast answer. Some improvement appears at four to six weeks, but the full effect takes three to six months. Stopping at week six because nothing has happened is the commonest reason people abandon a medicine that would have worked

🔬 Monitoring that comes with it

Leflunomide requires blood tests, and this is not optional. A typical schedule is liver enzymes and a full blood count every two to four weeks for the first six months, then every eight to twelve weeks. Blood pressure is checked at each visit, because leflunomide raises it in a minority of people.

💡 Side effects and what to do about them

Leflunomide is also avoided in significant liver disease, active serious infection, severe immunodeficiency and severe low blood counts. Alcohol adds to the liver load, and live vaccines are not given during treatment.

⚡ When first-line treatment is not enough

If a conventional DMARD does not bring disease activity down within three to six months, treatment steps up. Olumiant (Baricitinib) is a selective JAK1 and JAK2 inhibitor taken as a tablet, usually 2 mg or 4 mg once daily, often alongside methotrexate. Being oral, it appeals to people who do not want injections.

JAK inhibitors carry a class warning covering serious infections, shingles, blood clots, major cardiovascular events and malignancy, drawn largely from a safety trial in older patients with cardiovascular risk factors. That warning shapes who gets them: they tend to be reserved for people who have failed conventional DMARDs and do not have those risk factors. Screening for tuberculosis and hepatitis B comes before the first dose, and shingles vaccination is often recommended.

🌡️ Managing pain while the DMARD works

DMARDs take months. Something has to cover the gap. Arcoxia (Etoricoxib) is a COX-2 selective NSAID used at 60 mg or 90 mg daily in rheumatoid arthritis, chosen partly because COX-2 selectivity is gentler on the stomach than older anti-inflammatories. It still carries the NSAID cardiovascular and blood pressure cautions, so it is not a choice for people with uncontrolled hypertension or established heart disease.

Short courses of prednisolone are the other bridging option, and they work quickly. The catch is what happens with long use: bone loss, weight gain, raised blood sugar, cataracts, thin skin. The goal is always the lowest dose for the shortest time, tapering off as the DMARD takes hold. Our arthritis category lists the options available here.

🫁 What rheumatoid arthritis does beyond the joints

This is a systemic disease, and the joints are simply where it is most obvious. The parts people are rarely warned about:

• ❤️ Cardiovascular risk roughly doubles, driven by chronic inflammation rather than cholesterol alone. Controlling the disease is itself cardiac protection
• 🫁 Lung involvement — interstitial lung disease and pleural inflammation. A new dry cough or breathlessness always needs investigating
• 👁️ Dry eyes and dry mouth from secondary Sjogren syndrome
• 🩸 Anaemia of chronic disease, which adds to the fatigue
• 🦴 Osteoporosis, from inflammation, reduced activity and steroid courses
• 👆 Rheumatoid nodules over pressure points such as the elbows
• 🧠 Depression, roughly twice as common as in the general population

🚬 Lifestyle measures with real evidence behind them

Most of what circulates online about diet and rheumatoid arthritis is marketing. A short list does hold up:

Stopping smoking

The single most effective non-drug action. It reduces disease severity and improves how well DMARDs work, including methotrexate and biologics.

Regular movement

Exercise does not damage inflamed joints, contrary to old advice. Swimming, cycling and supervised strength work reduce pain and fatigue and protect the muscle that stabilises the joints.

Weight management

Lower body weight improves the odds of reaching remission and takes load off knees and hips.

Vaccination

Influenza and pneumococcal vaccines matter more than usual on immune-suppressing treatment. Live vaccines are avoided.

Dental care

Treating gum disease is associated with lower disease activity.

Omega-3 fats

Modest evidence for reduced joint tenderness and less need for painkillers. A helpful addition, never a replacement for a DMARD.

Fatigue responds better to pacing and graded activity than to rest. Energy conservation, joint protection techniques and assistive tools are what occupational therapy contributes, and it is worth asking for a referral rather than waiting to be offered one.

🚨 Symptoms that need attention quickly

• Fever, chills or an infection that does not settle while on a DMARD or JAK inhibitor
• New breathlessness or a persistent dry cough
• Yellowing of the skin or eyes, dark urine, pain under the right ribs
• Unusual bruising, bleeding gums or a sore mouth — possible low blood counts
• A hot, exquisitely painful single joint — septic arthritis must be excluded urgently
• Numbness, weakness or neck pain with arm symptoms in long-standing disease
• Pregnancy, planned or discovered, while taking leflunomide or methotrexate

❓ Frequently asked questions

📑 Sources and editorial

• ACR and EULAR classification criteria and treatment recommendations for rheumatoid arthritis
• Prescribing information for leflunomide, including monitoring and the accelerated elimination procedure
• Prescribing information for baricitinib, including the class safety warning for JAK inhibitors
• Trials comparing leflunomide with methotrexate, and trials of treat-to-target strategies
• Research on smoking, the shared epitope and anti-CCP antibodies in rheumatoid arthritis
• Related reading: periarthritis, fibromyalgia and rheumatic disease
• Related products: Arava (Leflunomide), Lefuheal (Leflunomide), Olumiant (Baricitinib), Arcoxia (Etoricoxib), arthritis category
• RXshop Editorial Team — reviewed by Daniel Kim, MD, Endocrinology