Diarrhea is also known as diarrhea. When diarrhea symptoms occur, dehydration may occur if the patient’s water intake is lower than the amount of water excreted. Dehydration can be classified as mild, moderate or severe. Initially, dehydration usually has no obvious manifestations and is difficult to detect, but at this time the body is already lacking water. Mild dehydration mostly occurs in the early stage of diarrhea, with less water loss and no obvious symptoms, and some patients may have mild thirst, nausea, weakness and mild decrease in urine output. At this time, if not controlled it may develop further, with symptoms such as vomiting, loss of skin elasticity, increased wrinkling, sunken eye sockets, no tears when crying, irritability, dizziness, and less urination, etc. At this time, there may be significant weight loss, about 5%-10%. It is recommended that if similar symptoms occur after diarrhea, promptly go to the hospital to avoid serious consequences. If the amount of body fluid loss is >10% of body weight, the patient has severe oliguria or even anuria, mania, delirium, convulsions, coma, and shock manifestations such as hypotension and skin pattern, which may threaten the patient’s life and require emergency resuscitation. Patients with diarrhea are advised to seek timely medical attention for rehydration, especially for those with acute diarrhea, such as oral sodium chloride solution and sugar solution. If the patient is severely dehydrated, rehydration can also be carried out by intravenous infusion of balanced salt solution to avoid serious harm to the organism, while the primary disease needs to be treated, such as the use of montelukast and other drugs for antidiarrheal treatment.