Over 50 million Americans have arthritis, both young and old. As well as causing aches and pains, arthritis is the number one cause of disability in the United States.

But how much do you really know about arthritis? Heathline talked to Nathan Wei of Arthritis Treatment Center in Frederick, Maryland, who is a board-certified rheumatologist with more than 33 years of patient interaction and clinic research experience. He helped us uncover the top 12 things that everyone — no matter their age — should know about the condition.

1. Arthritis isn’t just aches and pains.

Arthritis can make it difficult for people to do the things they love, and it can cause lasting damage, including permanent joint damage, and even affect your organs and skin. “Some forms of arthritis are systemic and serious,” says Wei. “For example, rheumatoid arthritis, the most common form of inflammatory arthritis, may affect internal organs and significantly shorten life span.”

2. And it’s not a single disease.

Though we use the term arthritis to describe a variety of conditions, they aren’t all the same. Wei says this term encompasses more than 100 different conditions. Osteoarthritis is the most common and affects people by wearing away the cartilage, which cushions bones at the joints. Other kinds of arthritis — like rheumatoid and psoriatic — are inflammatory in nature and are a result of the immune system attacking the joints.

3. Symptoms can vary, too.

The symptoms of arthritis include stiffness, pain, swelling, and decreased range of motion. They can range from mild to debilitating, can come and go, be constant, or worsen gradually over time.

4. What you eat matters.

Inflammatory foods like red meat can worsen the symptoms of arthritis, according to Wei. Also, gaining weight can aggravate arthritis, as fat cells produce leptin, which he says further aggravates inflammation.

5. Exercise can help.

Proper exercise can help, not hurt arthritis. “People with arthritis are often afraid to exercise because they think it might do harm,” says Wei. But just the opposite is true. “Proper exercise should be viewed as a medicine.”

6. Early intervention is key.

“The time to intervene with arthritis is early,” says Wei. “Don’t wait.”

7. You shouldn’t wait to see a specialist.

While you may call on your primary care doctor, Wei says a specialist in rheumatology may be necessary in some situations. “Any time symptoms of aches and pains persist longer than a few weeks or interfere with activities of daily living, it’s time to see a specialist,” he says.

8. Even babies can have arthritis.

We usually think of arthritis as something that affects only older people, but that isn’t always the case. Even the youngest of us can suffer from some types of arthritis. Wei says signs that your baby might suffer from arthritis include: “unexplained fever, swollen lymph nodes, limping, and a failure to thrive.”

9. Arthritis rarely requires surgery.

This is because arthritis can often be put into remission, and because new treatments like stem cells can be used to treat conditions like osteoarthritis.

10. Don’t overdo the cortisone.

Cortisone injections have their place for certain problems, but a patient should never get more than three per year in any given joint, according to Wei. Cortisone injections come with a fairly long list of potential complications, including deterioration of the cartilage within a joint, which can actually worsen arthritis.

11. Supplements have their place.

Most people opt for pharmaceuticals, but Wei says there is evidence that supplements like glucosamine and chondroitin can be helpful in the treatment of osteoarthritis.

12. It can be put into remission.

People commonly think of arthritis as a chronic condition — one that they’ll have to live with indefinitely. But Wei says that isn’t always the case. Even forms of severe arthritis, like rheumatoid and psoriatic, can be put into remission.