煎药之法各殊∶有先煎主药一味，后入余药者，
有先煎众味，后煎一味者，有用一味煎汤以煎药者；
有先分煎，后并煎者；有宜多煎者（补药皆然）；有
宜少煎者（散药皆然）；有宜水少者；有不煎而泡渍
者；有煎而露一宿者；有宜用猛火者；有宜用缓火者；
各有妙义，不可移易。今则不论何药，惟用猛火多煎，
将芳香之气散尽，仅存浓浓之质。如煎烧酒者，将糟
久煮，则酒气全无矣，岂能和营达卫乎？须将古人所
定煎法，细细推究，而各当其宜，则取效尤捷。
其服药亦有法。古方一剂，必分三服，一日服三
次；并有日服三次，夜服三次者。盖药味入口，即行
于经络，驱邪养正，性过即已，岂容间断？今人则每
日服一次，病久药暂，此一暴十寒之道也。又有寒热
不得其宜，早暮不合其时，或与饮食相杂，或服药时
即劳动冒风，不惟无益，反能有害。至于伤寒及外症
痘症，病势一日屡变，今早用一剂，明晚更用一剂，
中间间隔两昼一夜，经络已传，病势益增矣。又发散
之剂，必暖覆令汗出，使邪从汗散；若不使出汗，则
外邪岂能内消？此皆浅易之理，医家病家，皆所宜知
也。又恶毒之药，不宜轻用。昔神农遍尝诸药而成本
草，故能深知其性。今之医者，于不常用之药，亦宜
细辨其气味，方不至于误用。若耳闻有此药，并未一
尝，又不细审古人用法，而辄以大剂灌之，病者服之
苦楚万状，并有因此而死者，而已亦茫然不知其何故；
若能每味亲尝，断不敢冒昧试人矣。此亦不可不知也。
煎药的方法各不相同：有的先单独煎煮一味主药，然后再加入其余的药物；有的先煎煮多种药物，最后再单独煎煮一味药；有的用一味药煎出的汤液来煎煮其他药物；有的先分开煎煮，然后再合并煎煮；有的适合多煎煮（补益类药物都是这样）；有的适合少煎煮（发散类药物都是这样）；有的适合水量少一些；有的不需要煎煮而只需浸泡渍；有的煎煮后需要露天放置一夜；有的适合用猛火；有的适合用慢火。每种方法都有其精妙之处，不可随意更改。现在的人不论什么药，只用猛火长时间煎煮，将芳香之气完全散失，仅剩下浓稠的质地。就像煎烧酒一样，如果将酒糟久煮，那么酒气就完全没有了，怎么能调和营卫呢？必须仔细推究古人所制定的煎药方法，使每种药都符合其适宜的要求，那么取得疗效就会更加迅速。
服药也有法则。古方一剂药，必定分为三次服用，一天服三次；并且有一天服三次、晚上也服三次的。因为药味入口后，立即在经络中运行，驱除邪气、扶助正气，药性发挥完毕后即停止，怎么容许间断呢？现在的人每天只服一次，病情长久而用药短暂，这是“一曝十寒”的做法。又有寒热调理不得当，早晚时间不合宜，或者与饮食混杂在一起，或者在服药时立刻劳动、冒受风寒，这不仅无益，反而有害。至于伤寒以及外科病症如痘症，病势一天内多次变化，今天早晨用一剂，明天晚上再用一剂，中间间隔两昼一夜，经络已经传变，病势更加增重了。还有发散的药剂，必须保暖覆盖使其出汗，使邪气从汗液排出；如果不使其出汗，外邪怎么能从内部消除呢？这些都是浅显易懂的道理，医生和患者都应该知道。另外，恶毒的药物，不宜轻易使用。从前神农遍尝各种药物从而编写成《本草》，所以能深知药物的性质。现在的医生，对于不常用的药物，也应该仔细辨别其气味，才不至于误用。如果只是耳闻有这种药，并没有亲自尝过，又不仔细审察古人的用法，就贸然用大剂量灌服，病人服用后痛苦万分，甚至有因此死亡的，而医生自己也茫然不知其中的原因；如果能每味药都亲自品尝，绝对不敢冒昧地拿人试药。这也是不能不知道的。
The methods for decocting herbs vary: some require decocting a single principal herb first, then adding the remaining herbs; some require decocting multiple herbs first, then decocting a single herb last; some use the decoction of one herb to decoct other herbs; some are decocted separately first and then combined; some should be decocted longer (this applies to all tonifying formulas); some should be decocted briefly (this applies to all dispersing formulas); some require less water; some do not need decoction but only soaking; some should be left exposed overnight after decoction; some require strong fire; some require gentle fire. Each method has its subtle rationale and cannot be arbitrarily changed. Nowadays, regardless of the herbs, people only use strong fire and long decoction times, causing the aromatic qi to dissipate completely, leaving only a thick consistency. It is like distilling liquor; if the lees are boiled for too long, the liquor aroma will be entirely lost, how can it then harmonize Ying (Nutritive Qi) and Wei (Defensive Qi)? One must carefully study the decoction methods established by the ancients, ensuring each herb is treated appropriately, so that therapeutic effects will be achieved more swiftly.
There are also rules for taking medicine. Ancient prescriptions divided one dose into three servings, taken three times a day; there were also cases of taking medicine three times during the day and three times at night. Once the medicinal taste enters the mouth, it immediately circulates through the meridians, expelling pathogenic factors and supporting healthy qi. Its action ceases once its potency is exhausted; how can interruptions be tolerated? Modern people take medicine only once a day, with prolonged illness and brief treatment, which is akin to "exposing it for one day and freezing it for ten days" (inconsistent effort). Furthermore, improper regulation of cold and heat, incorrect timing in morning and evening, mixing with food, or exertion/exposure to wind immediately after taking medicine not only fails to help but may cause harm. Regarding Shanghan (Cold Damage) and external conditions such as smallpox, the disease status changes frequently within a day. If one dose is taken in the morning and another the next evening, with an interval of two days and nights, the pathogens have already transmitted through the meridians, and the disease severity increases. Additionally, dispersing formulas must be taken while keeping warm and covered to induce sweating, allowing pathogens to disperse through sweat; if sweating is not induced, how can external pathogens be eliminated internally? These are elementary principles that both physicians and patients should know. Moreover, toxic herbs should not be used lightly. In ancient times, Shennong tasted numerous herbs to compile the Bencao (Materia Medica), thus deeply understanding their properties. Contemporary physicians should also carefully distinguish the flavor and nature of rarely used herbs to avoid misuse. Merely hearing about a herb without tasting it oneself, and failing to carefully examine ancient usage methods, yet rashly administering large doses, causes patients immense suffering, and even death, while the physician remains ignorant of the cause. If every herb were tasted personally, no one would dare to recklessly test them on humans. This is also something one must know.