Lyme disease: Caused by a certain type of bacteria transmitted to humans via tick bites, Lyme disease brings about fever, a distinctive red skin lesion in the shape of a bull’s-eye, problems with the nerves and/or heart, and arthritis. Antibiotics are the treatment of choice for this disease.

       Reactive arthritis: An inflammation of the joints, reactive arthritis strikes along with or shortly after the onset of an infection, often one that is intestinal or sexually-transmitted. The three problems generally associated with reactive arthritis are arthritis, conjunctivitis (inflammation of the eyelid’s lining), and urethritis (inflammation of the urethra).

       Scleroderma: The word scleroderma means hard skin. This is a rare autoimmune condition that involves an attack on tiny blood vessels in many places in the body, and overproduction of collagen in places it doesn’t belong. The skin and other organs can stiffen. Joints can become inflamed, and tightness of the skin overlying the joints can make them even harder to move. An autoimmune disease, scleroderma usually attacks adults rather than children.

       Systemic lupus erythematosus: This is yet another disease caused by an immune system gone wrong. In lupus, the body attacks its own tissue, causing inflammation, joint pain, stiffness, permanent damage to the joints, and exhaustion. Although lupus most often affects women of child-bearing age, it does strike some men and can occur at nearly any age, including childhood and post-menopause.

       Bursitis and tendonitis: Caused by overusing or injuring a joint, bursitis is the inflammation of the fibrous sac that cushions the tendons. Tendonitis is the irritation of the tendons, which attach the muscles to the bones.

       Paget’s disease: With Paget’s disease, the breakdown and rebuilding of bone speeds up. The resulting bone is larger but also softer and weaker, making it more likely to fracture. These weakened and deformed bones cause arthritis to develop in their respective joints, which typically include those of the hip, skull, spine, knee, and ankle. The cause is unknown.

       Polymyalgia rheumatica (PMR): With this condition, severe stiffness can suddenly strike in the lower back, hips, shoulders, and neck, making it difficult even to get out of bed. The pain is similar to that of RA, often without evidence of any active arthritis. PMR can occur by itself or together with a life-threatening inflammation of the blood vessels called giant cell arteritis (GCA). Symptoms of GCA can occur before, after, or at the same time as PMR, and include headaches, scalp tenderness, hearing problems, vision loss or changes, and tongue or jaw pain after prolonged chewing.HYPERSENSITIVE FINGERS AND TOESPrompted by arterial blood vessel spasm, Raynaud’s phenomenon is a condition that can make the fingers, toes, nose, or nipples extremely sensitive to cold and to emotional upsets, turning them blue/violet or white in color. It sometimes occurs in conjunction with (or as a result of) other arthritis-related conditions including lupus, scleroderma, RA, and myositis, but can also be caused by repetitive trauma or injuries to the nerves of the hands or feet, smoking, certain medications, or chemical exposure. Typical attacks of Raynaud’s phenomenon include tingling, numbness and whitening of the fingers (without affecting the thumb), and pain or redness when blood circulation returns.There's no single blood test for Raynaud's: most doctors diagnose the disease based on signs and symptoms. Treatment generally involves wearing gloves, socks, and hats to maintain total body warmth, and avoiding workplace triggers, such as vibrating tools, freezers, and exposure to air conditioning vents. In severe cases of Raynaud’s, doctors prescribe medication to dilate the blood vessels. See Chapter 5 for more on Raynaud’s phenomenon.

       Sjögren’ssyndrome: Another autoimmune disease, Sjögren’s syndrome (usually referred to simply as Sjögren’s) causes inflammation of the tear glands and saliva glands, leading to dryness of the eyes and mouth, hazy vision, cracks at the corners of the mouth, and cavities. Inflammation of the brain, nerves, thyroid, lungs, skin, liver, kidneys, and, of course, the joints may also be present.

       Carpal tunnel syndrome: This syndrome results when pressure on a nerve in the wrist makes the fingers tingle and feel numb. This syndrome is usually caused by overuse of the wrist. Permanent muscle and nerve damage can occur if carpal tunnel isn’t treated.

       Fibromyalgia: Also known as fibromyalgia syndrome (FMS), this condition involves pain in the muscles and tendons that occurs without a specific injury or cause. Fibromyalgia can make you “hurt all over,” particularly in certain tender points in the neck, upper back, elbows, and knees. Those with fibromyalgia can suffer from disturbed sleep, fatigue, stiffness, and depression. The cause is unknown. Physical or mental stress, fatigue, or infections may trigger this disease.

       Myositis: This disease causes inflammation of the muscles, which can take one of two forms: polymyositis — an inflammation of the muscle that causes muscle weakening and breakdown, as well as pain, and dermatomyositis — polymyositis plus rashes that can lead to skin scarring and changes in pigmentation.

       Joint pain: This not only includes steady, ever-present pain, but also off-again-on-again pain, pain that occurs only when you’re moving or only when you’re sitting still. In fact, if your joints hurt in any way for more than two weeks, you should see your doctor.

       Stiffness or difficulty in moving a joint: If you have trouble getting out of bed, unscrewing a jar lid, climbing the stairs, or doing anything else that involves moving your joints, consider it a red flag. Although difficulty moving a joint is most often the result of a muscular condition (like tendonitis due to overuse, or muscle ache), it could be a sign of arthritis.

       Swelling: If the skin around a joint is red, puffed up, hot, throbbing, or painful to the touch, you’re experiencing joint inflammation. Don’t wait. See your doctor.