A middle-aged patient came to the clinic complaining of unexplained intermittent fever with no accompanying symptoms and no prodromal symptoms since he returned from a trip to Singapore and Malaysia in May of this year, with each fever ranging from 38.5-39.5 degrees Celsius and then spontaneously subsiding in half a day. PET-CT and other various tests only showed increased colorectal strip metabolism. When he came to the clinic, he said that he had no fever for a week, but in January at the most, he would definitely have a “spontaneous fever”, and that he was in good spirits, with only a bitter mouth, good appetite, normal bowel movements, and a slightly slippery pulse. He was prescribed Chai Hu: he was seen again a week later, no fever, and added Yin Chen, Yu Jin, and Serpent’s Tongue: Chai Hu 10, Han Xia 10, Huang Lian 3, Scutellaria 10, Radix Codonopsis 10, Roasted Licorice 5, Dazao 10, Yin Chen 15, Yu Jin 10, and Serpent’s Tongue 15. At the follow-up visit two weeks later, there was still no fever, and the bitterness in the mouth disappeared. At that time, the Chai Hu was removed, and the healing was continued, and the Gui Zhi was used: Gui Zhi 10, Radix Panax 10, Radix Scutellariae 10, Radix Scutellariae 3, Radix Scutellariae 10, Radix Codonopsis 10, Radix Glycyrrhiza Uralensis 5, Ziziphi jujubae 10, Inocerum 15, Yu Jin 10, Serpent’s Tongue 15, Chen Pi 6, Sha Ren 5. At the follow-up visit two more weeks later, there was no fever again, and the original formula was continued, and the two weeks were over. Reviewing this strange treatment process: intermittent fever, can it be solved by “cold-heat exchange”? Since we could not find out the cause of the fever by modern examination, we tried to use the ancient concept of medicine, fearing that Chai Hu was not enough, so we added Yin Chen, Yu Jin, and Snake Tongue Herb at the second follow-up. The patient was a middle-aged man with a biased diet, so dampness and heat were inevitable. At the same time, the strange disease may have phlegm in it, plus Xia Ku Cao, which softens and dissolves phlegm, combined with the original formula’s half-xia, the composition of the right medicine, both are regulating the liver, one is good at collecting, one is good at unblocking. It is suitable when phlegm and dampness are blocked in the lung and stomach and do not descend, while Xia Ku Cao belongs to the liver and gallbladder, and is used when the liver and gallbladder qi is rising. Radix Panax notoginseng is dry and open, good for treating damp phlegm; Xia Ku Cao is cold in nature, scrofulous phlegm nucleus, mostly caused by liver qi stagnation, which turns into fire for a long time, and phlegm and fire stagnation, so Xia Ku Cao is treating fire phlegm. So far, it has been earlier than 3 months, the patient occasionally came to the regimen, and no more fever. In fact, the examination should still be checked, otherwise, we have no direction to start, right?