In the early stage, there may be non-specific symptoms such as fatigue, weight loss, loss of appetite, excitement, and apathy, and then gradually affect the skin and mucous membranes, digestive system, and nervous system.

(1) Skin and mucosal damage: the most typical, often occurring or aggravated in summer and ameliorated or subsided in winter; often symmetrically involving the skin and mucous membrane of exposed parts and friction and pressure parts; the skin lesions initially appear to be edematous and bright red. The spots have clear boundaries and are similar to sunburns. Blisters may appear on them, causing itching and burning. After a few weeks or months, they will turn into dark red, brown-red or even brown-black. Those with repeated attacks will show infiltration and hypertrophy, deepening of skin striae, and Rough, desquamated, chapped, shrunken, etc. When the oral and esophageal mucosa is involved, increased salivation and pain may occur, which affects eating; when the rectal and vaginal mucosa is involved, increased secretions and even ulcers may occur.

(2) Digestive system damage: Often accompanied by a reduction or lack of gastric acid, symptoms such as loss of appetite, nausea, vomiting, indigestion, abdominal distension, abdominal pain, and diarrhea often occur.

(3) Nervous system damage: individual differences are large, but neurasthenia syndrome is the most common, mainly manifested by irritability, dizziness, vertigo, insomnia, fatigue, lack of energy, and forgetfulness. It can also manifest It is a mental symptom (such as depression, delirium), and severe cases can develop into dementia. Patients may experience peripheral nerve symptoms (such as numbness of limbs, loss of muscle strength, decreased or absent tendon reflexes, decreased peripheral sensation, etc.), and may even develop myelitis.