There are some small red bumps on my thighs

The appearance of small red bumps on the body is most likely caused by allergies. When a patient encounters a substance that causes allergies, the body will naturally react abnormally, and one of the symptoms is the appearance of small red bumps. Another type of allergy is the occurrence of disease caused by sensitivity of certain organs or tissues. The more common diseases caused by allergies include allergic asthma, allergic rhinitis, etc.

1. Urticaria

It is a skin manifestation of allergy, characterized by paroxysmal skin itching and the appearance of congested wheals. It is mostly caused by allergens (mostly certain foods and additives, inhalants, drugs, microorganisms and parasites, insect toxins, etc.) coming into contact with the patient's skin and mucous membranes and entering the body. Clinically, it is divided into two categories: one is type I allergic urticaria mediated by nonspecific immunoglobulin IgE, and the other is non-allergic urticaria, including physical, cold, heat, solar and cholestatic urticaria. In addition, physical factors, mental factors and systemic diseases can also cause urticaria. Other skin manifestations of allergies may include angioedema, dermatitis, eczema, erythema multiforme, exfoliative dermatitis, etc.

Clinical manifestations: Pink wheals of varying sizes suddenly appear on the skin, mostly in round, oval or irregular shapes, and can occur on any part of the body; they are isolated or scattered at first, then gradually expand and may merge into patches. Urticaria usually comes and goes quickly, one after another, and new wheals will occur one after another, and may even occur on top of old wheals. In some patients, the gastrointestinal tract may be affected, causing edema of the mucosa in this area, and abdominal pain and diarrhea may occur clinically. If the laryngeal mucosa is affected, breathing difficulties may occur. Severely ill patients may experience symptoms of anaphylactic shock such as palpitations, irritability, nausea and vomiting, difficulty breathing, laryngeal edema, and even low blood pressure.

2. Allergic rhinitis

It is mostly the result of the interaction between inhaled allergens and the patient's nasal mucosa. Most patients have allergic constitution and it is hereditary. Clinically, rhinitis can be roughly divided into seasonal rhinitis and perennial rhinitis. The former is mostly caused by inhalation of pollen, while the latter is mostly caused by inhalation of indoor dust, mites, mold, animal hair, dander, and poultry feathers.

Clinical manifestations: sudden nasal itching, continuous sneezing (usually more than 5 times) and large amounts of clear watery serous nasal secretions. Each attack lasts for more than 1 hour and often recurs.

3. Anaphylactic shock

It is the most serious allergic reaction. The most common allergen causing this disease is penicillin. Other drugs include beta-lactam antibiotics, streptomycin, procaine, isatis root injection, dextran, iodine-containing contrast agents, etc. In addition, there are also certain insect stings. The incidence of anaphylactic shock in the general population is approximately 0.08%. After the onset of the disease, patients experience widespread and rapid increase in capillary permeability, arteriolar dilation, resulting in a decrease in peripheral blood flow, a decrease in cardiac output and a sharp drop in circulating blood volume, as well as edema of multiple organ and system tissues and smooth muscle spasm. In severe cases, it can be fatal in a very short time. 20% of allergic deaths occur within half an hour of the onset of the allergy.

Clinical manifestations: Patients first experience flushing of the skin and mucous membranes, itching all over the body, especially on the palms, numbness of the lips, tongue and extremities, followed by various rashes, mostly in the form of large wheals, and large areas of dermal and subcutaneous angioedema. Blood pressure drops sharply, with systolic pressure dropping below 80 mmHg and pulse pressure within 20 mmHg. In severe cases, circulatory failure may occur, manifested by confusion, cold sweat, pale complexion, cold limbs, and thin pulse. If the disease is not controlled in time, cardiac arrest and even death may occur within a short period of time in a few cases.

4. Hay fever

The disease, also known as hay fever, is caused by the patient's allergy to plant pollens and mainly affects the eyes and upper respiratory tract. Most of the diseases are caused by pollen as an allergen, which is spread by wind. The main pathogenic pollens in my country include pollen from the genus Eupatorium, as well as pollen from sunflower, hemp, sycamore, castor, Amaranth, Cucurbit, poplar, and elm. A small number of patients are also caused by fungi, dust mites or other inhaled substances or foods with obvious seasonality.

Clinical manifestations: It has obvious seasonality and regionality, and the main manifestations are itchy eyes, tearing, and red and swollen eyelids; itchy nasal cavity, continuous sneezing, often up to a dozen times at a time, and increased watery secretions after sneezing, which do not stop all day when the disease occurs; itchy throat, dry throat, dry cough, etc. Wheezing may be heard by auscultation in some patients.

5. Allergic asthma

This disease is the main type of bronchial asthma. It is a generalized airway hypersensitivity state caused by allergens or other allergic factors, resulting in an airway obstruction syndrome characterized by reversible and spasmodic airway stenosis. The lesions mainly affect the bronchi. The main causes of the disease are inhaled allergens (indoor dust, house dust mites and dust mites, as well as fungal spores, various plant pollens, animal dander, feathers, silk, old fabrics, insect limbs, debris, feces, molting, insect eggs, etc.), food (such as certain eggs, etc.), and drugs (aspirin, etc.). Not all cases of bronchial asthma are related to allergies. Other types of bronchial asthma include: infectious asthma caused by infection, exercise-induced asthma caused by physical exercise, psychogenic asthma caused by mental factors; occupational asthma caused by occupational exposure to certain non-specific irritants; and asthma caused by non-sensitizing factors (such as cold air, menstruation, pregnancy, childbirth, etc.).

Clinical manifestations: often sudden onset or aggravation, presenting as paroxysmal expiratory dyspnea and wheezing, usually lasting several hours. Before an attack, there are often precursors of mucosal allergies such as sneezing, runny nose, and coughing, followed by a feeling of chest tightness. In severe cases, there is cyanosis, sweating, sitting position, and even loss of consciousness. The symptoms may be relieved by taking antiasthmatic drugs or by themselves. When the symptoms are relieved, thick foamy sputum can be coughed up. The main finding on physical examination is widespread wheezing during expiration.