What is the cause of flu-like symptoms from vaping?

Symptoms similar to those of the flu appear after using electronic cigarettes. This is very likely a clear warning signal from the body, which usually indicates that you may be experiencing "e-cigarette or e-cigarette product use-related lung injury", often abbreviated as EVALI. This is a serious and potentially life-threatening lung disease.
⚠️ EVALI: Not Just "E-cigarette Flu"
The symptoms of EVALI are almost identical to those of influenza or pneumonia, which is one of its most dangerous features. This is why many users mistakenly believe they have just caught the flu and delay seeking medical treatment.
Typical symptoms: The symptoms will suddenly occur or rapidly worsen, mainly including:
Respiratory symptoms: coughing, shortness of breath, chest pain.
General symptoms: fever, chills, headache, muscle pain, fatigue, unexplained weight loss.
Gastrointestinal symptoms: nausea, vomiting, abdominal pain, diarrhea.
Serious consequences: EVALI is a severe acute disease. Approximately 90% of the reported cases require hospitalization. As of the beginning of 2020, it had caused nearly 3,000 hospitalizations and nearly 70 deaths in the United States alone.
?? The cause of EVALI: What exactly happened in the lungs?
The fundamental cause of EVALI is that certain chemicals in e-cigarettes have caused direct chemical damage to the lungs. Although the exact combination of harmful substances is still under investigation, the most definite culprit is Vitamin E Acetate, which has been confirmed as one of the main pathogenic substances.
Vitamin E acetate: It is often illegally added as a thickening agent to electronic cigarette products that contain tetrahydrocannabinol (THC, the main psychoactive component in marijuana). Under normal circumstances, applying it to the skin or taking it orally is safe, but when inhaled after being heated, it will severely impede the normal functioning of the lungs, causing serious damage.
Other harmful chemicals: The chemicals in the e-liquid may generate new harmful substances during the heating and vaporization process, or release toxic metal particles such as nickel, tin, and aluminum. These can cause continuous damage and inflammation to the lungs.
?? What should I do if I have flu-like symptoms?
Given the high similarity between EVALI symptoms and ordinary flu, the US CDC has issued a special guideline. If you have the above symptoms, especially in the context of knowing that you are using e-cigarettes, you must take the following actions:
Stop using immediately: The first and perhaps the most important step is to immediately stop using any electronic cigarette products to prevent further harm.
Seek medical attention promptly: Please contact a doctor immediately or go to the emergency room. Make sure to inform the doctor that you have a history of using e-cigarettes recently. Provide information such as the brand, product type (especially whether it contains THC), and the purchase channel. This will be very helpful for the doctor to make a diagnosis.
Be vigilant against dehydration: The propylene glycol (PG) and vegetable glycerin (VG) found in e-cigarettes have hygroscopic properties, which can cause dehydration in the body, exacerbating symptoms such as fatigue and headaches similar to those of a cold. Before and after seeking medical treatment, make sure to drink plenty of water.
Obtaining an accurate diagnosis: EVALI is an "exclusionary diagnosis", meaning that doctors need to conduct examinations and tests to rule out other possible conditions (such as influenza, pneumonia, COVID-19 infection, etc.) before a definite diagnosis can be made. Do not assume it is influenza and avoid seeking medical treatment on your own.
Seeking Help: If diagnosed with EVALI, doctors may use medications such as corticosteroids for treatment. At the same time, you can also consult with the doctor about strategies for quitting smoking or giving up e-cigarettes, as well as available support resources.
?? Summary
In conclusion, the flu-like symptoms that occur after vaping should not be taken lightly. This is likely a warning sign of EVALI, a serious lung injury that requires immediate medical intervention. The core action is: stop vaping immediately and inform the doctor at once.