When your joints are sore and achy, you might assume you have arthritis. But if that joint pain strikes when you're still in your 30's, or even your 20's, it might be another condition entirely. You might have an autoimmune disease called systemic lupus erythematosus, or lupus, for short.

An autoimmune disease means that your immune system, which normally serves as your body's first defense against infections, mistakenly attacks your own tissues. Imagine if you hit your hand over and over and over again. The skin would turn red and swell up, and it would probably hurt quite a bit. Well, the same kind thing happens inside your body when your immune system attacks your tissues. They swell up, and they hurt.

Almost everyone with lupus has joint pain and swelling, but depending on what part of your body the lupus is attacking, you could have other symptoms too. If it's your skin, you might have a rash on your face and body. If lupus attacks your digestive tract, you might feel sick to your stomach. If it attacks your brain or nervous system, you may have numbness, tingling, vision problems, and headaches.

So, how do you know that you have lupus?

Your doctor will ask about your symptoms, listen to your heartbeat, and examine your nervous system. Doctors often use a test to check for antinuclear antibodies, the immune substances that attack your tissues. You'll likely also need other blood or urine tests, and perhaps an x-ray, CT, ultrasound or biopsy, depending on your symptoms. Taken together, your symptoms and the results of these tests can help your doctor determine whether you have lupus.

If you do have lupus, lupus is a chronic condition, but, you can control its symptoms. For example, taking steroid medicines by mouth might help control the overactive immune response that's causing your lupus. Steroid creams can treat skin rashes. For achy joints, non-steroidal anti-inflammatory medicines like ibuprofen, and anti-malaria drugs might help. You may need stronger drugs if these medicines alone don't control your lupus symptoms.

When you have lupus, you need to be extra careful about your health. Wear sunscreen and protective clothing whenever you're out in the sun, so your skin doesn't get even more irritated. Stop smoking and make sure you're up-to-date on your vaccines. Have your heart checked regularly because lupus can cause heart complications.

Lupus can be a lifelong journey, but life with lupus is a lot better today than it was just a few decades ago. Improved treatments can help control your joint pain and other symptoms so you can live a pretty normal life. To improve your outlook with lupus, stay on top of your health care, and do call your doctor right away if your symptoms get worse or you develop any new symptoms.