Whenever you are hot, you will get a red rash on your neck, considering that it is caused by prickly heat, folliculitis, urticaria and so on. 1. prickly heat: prickly heat is related to the hot and humid environment, sweat duct obstruction, etc., the patient’s main manifestation is that the skin has raised small blisters, papules or mounds of herpes, which may be accompanied by tingling or itching sensation, which may cause some patients to appear as soon as the heat of the neck on the phenomenon of red rashes. 2. Folliculitis: folliculitis is related to hair follicle damage, Staphylococcus aureus infection, etc., while sweating, wearing tight clothes, etc. is the trigger. Folliculitis patients will appear localized skin red pimples, may also be accompanied by itching, tenderness, stinging and other uncomfortable symptoms, so it can also be manifested as a hot neck on the red rash. 3. urticaria: urticaria can also cause some patients with a hot neck on the red rash, may also be accompanied by itching, severe cases with fever, nausea, vomiting and other symptoms. The appearance of hives is related to infections, contact with allergic substances, physical factors and so on. It is recommended that people who get red rashes on their necks when they are hot should consult a doctor for an examination to determine the cause of the rash and then follow the doctor’s instructions for treatment. Pay attention to local skin care and avoid scratching the neck area with hands or foreign objects.