Rheumatoid arthritis is a systemic autoimmune disease characterized by chronic erosive arthritis, with a total prevalence of more than 5 million people in China. The main pathological manifestation is synovitis, which can involve multiple joints throughout the body, in addition to joint lesions, rheumatoid arthritis over time can also appear some extra-articular secondary damage, such as interstitial lung lesions, dry syndrome, osteoporosis, etc. This paper describes the common secondary damage of rheumatoid arthritis and its prevention and treatment. Interstitial lung lesions are one of the most common extra-articular lesions in rheumatoid arthritis and have a high incidence in rheumatoid arthritis, with about 1,6%-4,0% of patients with rheumatoid arthritis reported to have interstitial lung lesions. Interstitial lung lesions are generally insidious, with about 70% of patients showing pulmonary involvement 5 years after the onset of arthritis, and are often missed in the early stages due to the absence of obvious clinical symptoms and signs, while irreversible interstitial fibrosis develops in the late stages, leading to death from respiratory failure. Clinically, interstitial lung lesions mainly manifest as progressive motor dyspnea, which can develop from activity to heavy resting state, and some patients are unable to move due to joint dysfunction without obvious dyspnea. On examination, pestle fingers and popping sounds can be heard in both lower lungs in the late stage, although the incidence of pestle fingers is significantly less than in patients with idiopathic pulmonary fibrosis. High-resolution CT of the lungs shows that interstitial lung lesions can be seen in 10%-47% of patients, mainly manifesting as diffuse ground glass-like infiltrative lung shadows in the early stage, and as the disease progresses, grid-like and reticulonodular shadows may appear, mainly involving the middle and lower lung fields; honeycomb lung manifestations appear in the late stage. The lesions are asymmetrically distributed in the lung fields bilaterally, and are evident in the outer bands and posterior basal segments. It has been shown that active rheumatoid arthritis, high titers of rheumatoid factor, positive anti-CCP antibodies, severe joint lesions and smoking are risk factors for the development of interstitial lung lesions secondary to rheumatoid arthritis. Therefore, in order to prevent the development of interstitial lung lesions by addressing the above risk factors, the first thing we can control is to quit smoking, control the activity of rheumatoid arthritis to avoid the development of joint lesions, and to check the lungs at least once a year with high-resolution CT to monitor the appearance and development of lung lesions. In terms of treatment, there is no unanimously accepted treatment protocol by experts and the treatment results are poor. Commonly used drugs include glucocorticoids, immunosuppressants, and anti-fibrotic (e.g., pirfenidone). Therefore, it is imperative to treat rheumatoid arthritis early and in combination with standardized treatment to control disease activity and prevent the development of interstitial lung lesions. It should be noted that once rheumatoid arthritis patients develop interstitial lung lesions, they must avoid infections, because infections often lead to aggravation of lung lesions, which can involve life when the lesions are severe. 2 .Dry syndrome Dry syndrome is a chronic immune disease with dry mouth and eyes as the main clinical manifestation, divided into primary and secondary. Secondary dry syndrome is secondary to rheumatoid arthritis, which usually appears several years after the onset of rheumatoid arthritis, and some reports show that about 20%-30% of rheumatoid arthritis patients will have secondary dry syndrome, and it is more common in women. For the diagnostic criteria of secondary dry syndrome, the 1992 European standard considers that: first of all, it is necessary to affirm the presence of a certain connective tissue disease, accompanied by (1) a dry eye feeling for more than 3 months, or a sandy feeling in the eye, or the need to use artificial tears more than 3 times a day. Anyone with either 1 of these is considered positive. Or (2) Have dry mouth for more than 3 months, or need to be brought down with water when eating, or have recurrent or persistent enlargement of parotid glands. One of them is positive, (3) Filter paper test ≤5mm/5min, or corneal staining index ≥4 is positive. (4) Mononuclear cell infiltrate foci ≥1/4mm2 on lower lip mucosal biopsy were considered positive. (5) Parotid angiography, salivary gland radionuclide scan, and salivary flow rate with any 1 positive item. If 2 of them are positive, the diagnosis is made. Because of the clinical concern for patients with invasive tests, we can also diagnose rheumatoid arthritis secondary to desiccation syndrome if there is a history of rheumatoid arthritis with positive SSA or SSB antibodies, generally with one of (1) or (2) positive. For dry syndrome there is no radical cure yet, but mainly alternative treatment and symptomatic treatment. For dry eyes, artificial tears, a substitute for tears, can be used. If artificial tears are effective but last for a relatively short time, silicone plugs or electrocautery can be used to close the tear dots. Patients must be instructed not to rub their eyes with their hands; use available warm soft towels to wet compress the eyes daily and apply eye ointment before going to bed; indoor light should be dim and avoid bright light stimulation; wear windproof glasses when going out in windy weather; avoid reading and watching TV for a long time and increase bed and sleep time. For dry mouth symptoms, you can take bromhexine, which has the effect of stimulating parotid secretion, but you must pay attention to keep the oral hygiene to avoid inducing fungal infection due to the decrease of oral saliva secretion. Due to the lack of moistening of teeth with fluid, rampant dental caries will appear, and regular dental checkups should be done to avoid its appearance. When dry syndrome involves organs (such as kidney and lung) it should be treated with hormones and immunosuppressants. Commonly used immunosuppressants include hydroxychloroquine sulfate, cyclosporine, cyclophosphamide, and total white peony glycosides. Beneficial qi and yin herbs are effective in improving dry mouth and dry eyes, and can be used for reference. 3 . Osteoporosis Osteoporosis (OP) is a systemic bone metabolic disease characterized by low bone mass and microstructural destruction of bone tissue, leading to increased bone fragility and easy fracture, mainly seen in the elderly, but can start at all ages. Rheumatoid arthritis is one of the main causes of secondary osteoporosis in clinical practice. Osteoporosis itself, without complications, has no symptoms such as pain. Early detection relies on bone densitometry. Vertebral compression fractures often occur unknowingly due to osteoporosis, and can also be induced by coughing, sneezing, or minor trauma. Some people may also exhibit peripheral aches and pains. Rheumatoid arthritis secondary to osteoporosis has the following main causes: firstly, osteoporosis is an early manifestation of bone erosion in rheumatoid arthritis, and osteoclasts and their enhanced function aggravate bone loss to appear as osteoporosis; secondly, the application of glucocorticoids during the treatment of rheumatoid arthritis is a key factor leading to osteoporosis. Glucocorticoids cause bone loss through multiple pathways, increase osteoblast differentiation and inhibit osteoblast growth, resulting in osteoporosis. The long-term use of NSAIDs immunosuppressants leads to impaired absorption of calcium and magnesium in the gastrointestinal tract, which also affects bone metabolism. Finally, patients with rheumatoid arthritis have osteoporosis due to painful deformities in the joints, which reduces activity, especially outdoor activities, and reduces the time of light, which affects the synthesis of vitamin D and further affects the absorption of calcium. For the above reasons, first of all, we should change our lifestyle, increase outdoor activities, extend the time of light, generally 1 hour of light in autumn and winter, half an hour in spring and summer can synthesize enough vitamin D to promote calcium absorption, eat more food with high calcium content such as milk, bone broth, shrimp, etc., and move appropriately to avoid falls. Secondly, increase pharmacogenic intake, supplement vitamin D preparations such as osteotriol and calcium tablets, and add osteoporosis improving drugs early in the treatment of rheumatoid arthritis. If patients take glucocorticoids, add phosphonates, such as alendronate tablets. It should be noted that alendronate tablets are usually taken in the morning on an empty stomach, drink more water, and cannot lie flat for half an hour after taking them to avoid their adverse effects. It is recommended that patients with rheumatoid arthritis should generally do a bone density check once a year to monitor their bone loss, and take appropriate preventive and therapeutic measures for changes in bone density, and can be hospitalized 1-2 times a year on a regular basis, with intravenous drips of bone peptide, deer melon polypeptide and other drugs that regulate bone metabolism to prevent osteoporosis. 4, anemia The incidence of rheumatoid arthritis with anemia is about 30%-70%, there are three main types: (1) chronic disease anemia is the most common. It is generally believed that rheumatoid arthritis is a chronic wasting disease, the disease will be accompanied by anemia, wasting. The anemia is usually mild or moderate orthocytic or orthopigmented anemia, but may also be hypochromic or microcytic. The degree of anemia is often associated with rheumatoid arthritis activity. Patients have lower than normal serum iron and total iron binding capacity, so transferrin saturation is normal or slightly below normal and serum ferritin is increased. (2) Iron deficiency anemia is often associated with inadequate dietary iron intake, impaired absorption of iron in the digestive tract and chronic blood loss in the digestive tract. It is often a small cell hypochromic anemia in which serum iron, total iron binding capacity, ferritin and transferrin saturation are reduced. (3) Treatment-related anemia: Long-term inappropriate application of glucocorticoids and NSAIDs in patients with rheumatoid arthritis, often combined with peptic ulcers, some patients with chronic small bleeding or complicated by acute upper gastrointestinal bleeding, can lead to anemia; a variety of immunosuppressive drugs can cause anemia in patients with rheumatoid arthritis due to suppression of bone marrow hematopoietic function. Anemia can aggravate systemic symptoms, reduce the quality of life and increase the death rate, so it should be given sufficient attention in the treatment of rheumatoid arthritis. In clinical practice, for chronic disease anemia and iron deficiency anemia, it is necessary to standardize the treatment plan of rheumatoid arthritis, monitor the blood routine regularly in clinic, and supplement iron therapy, such as ferrous succinate and iron polysaccharide complex, etc. Iron supplementation should adhere to the principle of “small amount and long-term”. Take the medicine strictly according to the doctor’s prescription, do not increase the dose on your own to avoid iron poisoning; take the medicine after meals and avoid taking it on an empty stomach to reduce nausea and vomiting caused by the stimulation of the drug on the gastrointestinal tract. Also take vitamin C or fruit juice, because the acidic environment is conducive to the absorption of iron. During the treatment period, coffee, strong tea and food containing tannic acid are prohibited, because tannic acid can generate insoluble iron precipitation with iron and prevent the absorption of iron. When the anemia is corrected, continued attention should be paid to consolidate the therapeutic effect through dietary iron supplementation. Iron-rich foods include animal liver, egg yolk, red dates, beans, lean meat, kelp, shrimp, nori, black fungus, mushrooms, etc. For anemia caused by drug-induced gastrointestinal tract damage, it is recommended to add gastric mucosal protective agents at the early stage of treatment to avoid gastrointestinal tract damage. 5, gastrointestinal reactions Rheumatoid arthritis is a chronic immune disease, which determines the need for patients to take drugs for a long time. Treatment of rheumatoid arthritis drugs whether non-steroidal anti-inflammatory drugs or immunosuppressants, for the gastrointestinal tract mucosa have a certain impact. Long-term may lead to corresponding indigestion symptoms, including abdominal discomfort, indigestion, belching, nausea, loss of appetite, vomiting, abdominal pain and diarrhea, etc. In severe cases, it can cause ulcers and gastrointestinal bleeding. Therefore, it is necessary to add gastric mucosal protective agents such as rabeprazole at the beginning of treatment, apply them in small doses as much as possible, choose cox-2 inhibitors to reduce adverse drug reactions, and avoid the combined use of NSAIDs and glucocorticoids and anticoagulants, as well as the simultaneous use of two NSAIDs. Also in patients with rheumatoid arthritis, if gastrointestinal symptoms are present, patients are advised to have a gastroscopy or 13C H. pylori monitoring, and if H. pylori is positive, treatment of H. pylori infection needs to be eradicated. In addition to the above lesions, extra-articular manifestations of rheumatoid arthritis can also involve the kidneys, skin, nervous system, etc. The incidence is relatively low, but in clinical practice, in order to avoid secondary rheumatoid arthritis, the most important thing is the standardized treatment of rheumatoid arthritis and long-term adherence to treatment, strict control of the development of the disease, which requires the joint efforts of patients and doctors to improve the rheumatoid This requires the joint efforts of patients and doctors to improve the quality of life of patients with rheumatoid arthritis.