Rheumatoid arthritis (RA) and lupus both cause joint pain and stiffness. Despite some similarities, it’s easy for doctors to distinguish them. RA has more debilitating effects on the joints.

Rheumatoid arthritis (RA) and lupus are sometimes confused early on because they share certain symptoms. They’re both autoimmune diseases that affect the joints.

An autoimmune disease occurs when your immune system attacks cells in your body, triggering inflammation and damaging healthy tissue. Experts aren’t sure of all the triggers of autoimmune diseases, but they can run in families.

However, doctors can distinguish them through diagnostic testing.

Keep reading to learn about the similarities and differences between RA and lupus.

Both RA and lupus cause joint pain and joint stiffness.

Both conditions can also cause your joints to become hot and tender, but this is more pronounced in RA.

RA and lupus both affect your energy levels, too. If you have either condition, you might feel constant fatigue or muscle weakness. A periodic fever is another shared symptom, but it’s more common in lupus.

Some risk factors are also shared between RA and lupus.

Females are at greater risk of having an autoimmune disease than males, according to research such as a 2020 literature review. In addition, both RA and lupus are more likely to affect females than males.

Did you know?

Although lupus is much more common in females than males, males tend to have more severe symptoms.

There are many differences between the symptoms of RA and lupus, including:

  • The parts of the body affected: RA primarily affects your joints, including the fingers, wrists, knees, and ankles, while lupus can affect any part of the body, including the internal organs and skin.
  • Symptoms they may cause: RA can also cause joints to swell or become misshapen. Joint swelling is common in RA but less common in lupus. Skin rashes are also common with lupus, while RA can sometimes cause painful skin nodules, though this is less common than other RA symptoms.
  • The time of day when pain is typically worse: Pain associated with RA is usually worse in the morning and tends to get better as the day progresses. The joint pain caused by lupus remains constant throughout the day.
  • Complications: Though less common with available treatment, RA can cause inflammation in the lungs and around the heart. Lupus can cause life threatening complications, which may include:

Both RA and lupus can be difficult to diagnose. This is especially true early on when there are few symptoms of either condition.

Because RA and lupus share some common characteristics, people at the very early stages of either condition can also be misdiagnosed with one when they have the other.

Once RA has progressed a bit, doctors can easily distinguish the two. For instance:

  • RA can cause bone erosion and structural irregularities if you don’t receive appropriate therapy.
  • Lupus rarely causes bone erosion. In instances where lupus does affect the joints (such as in Jaccoud arthropathy), the effects are less disabling than in RA and often reversible. Jaccoud arthropathy is a non-erosive, inflammatory response that leads to the thickening of the joint capsule.
  • Lupus often affects the kidneys, causes anemia, or leads to weight changes.
  • RA can also cause anemia, but lung issues occur more frequently.

Doctors can usually make a diagnosis by evaluating your symptoms and ordering blood tests. Blood tests can check the health of your organs and see if something else could be causing your symptoms.

You may also need imaging tests to look for signs of joint damage or symptoms affecting your internal organs.

RA classification criteria

Criteria used to classify these conditions in clinical trials are often used as guides for diagnosis.

For an RA diagnosis, you should receive at least 6 points on the RA classification scale devised by the American College of Rheumatology (ACR) and the European League Against Rheumatism (EULAR).

The scale was last updated in 2010. Points are awarded in the following manner:

  • You have symptoms that affect at least one small joint or at least two large joints (2 to 5 points).
  • The antibodies rheumatoid factor or anti-cyclic citrullinated peptide are present in your blood (2 or 3 points).
  • You have elevated levels of C-reactive protein or erythrocyte sedimentation, which are markers of inflammation (1 point).
  • Your symptoms last at least 6 weeks (1 point).

Lupus classification criteria

Systemic lupus erythematosus (SLE) is the most common type of lupus.

According to 2019 criteria from the ACR and EULAR, you must have antinuclear antibodies to receive an SLE diagnosis. In addition, you must meet at least one other criterion (some of which are included below) and accumulate at least 10 points:

Comorbidity refers to having more than one disease at the same time. This is also known as disease overlap or overlap disease.

People with RA and people with lupus can have symptoms of other conditions. It’s also possible for you to have symptoms of both RA and lupus.

There’s no limit to how many chronic conditions you can have, and there’s no time limit for when you can develop another chronic condition.

Diseases that often overlap with RA include:

Diseases that often overlap with lupus include:

For rheumatoid arthritis, many medications are available to help you manage your symptoms and prevent joint damage.

Sometimes, a doctor may recommend a knee or hip replacement if the joint becomes too damaged over time.

For lupus, treatment can also help you manage the symptoms.

Many people with lupus take prescription medications to help treat joint inflammation and pain. The Food and Drug Administration (FDA) has approved two SLE medications:

  • belimumab (Benlysta), which is FDA approved to treat lupus nephritis
  • anifrolumab-fnia (Saphnelo), which is taken in combination with other lupus medications

You might need medication to treat skin rashes, heart disease, or kidney problems associated with either condition. Sometimes, a combination of several medications works best.

Though rare, people with either condition might get cortisone shots to manage the inflammation. However, corticosteroids are rarely used now because of the high risk of side effects.

If you have RA or lupus, treatment typically involves a long-term plan with a doctor or healthcare professional. This plan will include ways to manage inflammation and pain and minimize complications.

  • permanent structural changes to the joint
  • anemia
  • lung damage

Treatment can help prevent long-term issues.

Long-term complications of lupus include heart and kidney damage.

People with lupus often have conditions affecting their blood, including anemia and inflammation of the blood vessels. Proper treatment of lupus can help prevent tissue damage.

Though RA and lupus are both autoimmune diseases, they have different symptoms and treatments.

In the early stages, the symptoms they cause can appear similar.

Treatment for both involves medications to manage symptoms and flare-ups and prevent complications.