Aromatic herbs have a very special function in transforming Dampness and breaking up the blockage of the Qi. They can penetrate into turbid Dampness because their light but sharp smells are able to separate the clean from the turbid. Meanwhile, their light but exceptional smell can wake up (stimulate) the internal organs that have been covered and confused by Dampness. The aromatic and pungent smells of these herbs can, on the one hand, stimulate the Spleen to transform Dampness and treat the causes of Dampness accumulation; on the other hand, they activate Qi movement so as to accelerate the functions of the involved organs.

In clinical practice, the aromatic herbs are often used to remove Dampness from the Middle Jiao, the Spleen and Stomach. They are also used for eliminating Dampness from the Liver and Gall Bladder as well as from the Heart. Some of them can open the orifices and treat ‘Lock-up syndrome’. They can also be applied topically to treat open wounds or trauma because they are able to transform the pus, dry Dampness, promote the movement of Qi and Blood, reduce swelling, stop pain and promote healing.

Although the functions of aromatic herbs are similar to those of the herbs that regulate the Qi, herbs that eliminate Dampness and herbs that clear Damp-Heat, they have their own specific characteristics and they do not fit easily into any of the herbal categories mentioned above. For this reason in many books they are included within the categories of herbs that aromatically transform Dampness, herbs that clear Summer-Heat, herbs that open the orifices and herbs for external usage.

Herbs that have an aromatic smell are able to transform turbid Dampness in the Middle Jiao and treat the syndrome of Dampness accumulation. This syndrome occurs in certain conditions. First of all, it happens when the Spleen is not able to transform Dampness in situations where there is Excessive-Dampness invasion or deficiency of the Spleen-Qi. Secondly, it can also happen when the Qi movement is disturbed in the Middle Jiao.

In this syndrome, Dampness as well as undigested food, Cold or Heat accumulate in the Middle Jiao and bring about symptoms and signs such as fullness in the chest, distension in the hypochondriac region and abdomen, a poor appetite, a sticky sensation in the mouth, nausea, vomiting, diarrhea or difficult defecation and heaviness of the body. Patients may have a thick, sticky, white or slightly yellow tongue coating and a moderate pulse.

In clinical practice, these herbs are usually used for Excessive syndromes—for example, Dampness invading the Middle Jiao caused by bad eating habits or consumption of unhygienic food, especially during a humid and hot summer. This syndrome can be seen in acute gastroenteritis, dysentery, hepatitis and gastric influenza. These herbs can also be used in Spleen-Qi deficiency syndrome such as in chronic hepatitis, hepatocirrhosis, cholecystitis and uremia, if combined with herbs that tonify the Spleen-Qi and regulate it.

There are many methods and herbs for treating Dampness: some herbs can drain out Dampness by promoting urination, some can dry Dampness directly and some can regulate the Qi to transform Dampness. The aromatic herbs that enter the Spleen and Stomach meridians can penetrate into turbid Dampness, wake up the Spleen which has been covered by Dampness, and stimulate the Spleen-Qi to transform Dampness as well as activating the Qi movement and therefore accelerating the process of transforming Dampness.

Huo Xiang and Pei Lan both are pungent and aromatic, and enter the Spleen and Stomach meridians. Both are able to transform Dampness in the Middle Jiao, revive the Spleen, improve the appetite and reduce fullness in the Stomach. They are especially often used to treat gastritis, hepatitis, cholecystitis and gastric influenza in the summer when the weather is humid and hot and the functions of Spleen and Stomach become weak.

Huo Xiang is slightly warm, aromatic and pungent. It can penetrate the turbidity and scatter the accumulation of Dampness and Heat. Its action is strong but not harsh and is particularly effective for regulating the Qi in the Middle Jiao, soothing the Stomach-Qi and treating nausea, vomiting and poor appetite.

Pei Lan is a neutral and gentle herb. Its light and fragrant smell can particularly separate the clean from the turbid in the Middle Jiao and revive the Spleen. It is effective for treating a sweet and sticky sensation in the mouth, or foul smell in the mouth, fullness in the chest, heavy limbs and a heavy sensation in the head. In Chinese, ‘ Pei’ means ‘wear’ or ‘ornament’; ‘ Lan’ means ‘orchid’. As Pei Lan has a nice smell, in ancient times it was often put in a small bag and carried by people under their clothes, like people use perfume nowadays.

These four herbs are aromatic and pungent and are able to expel Wind, Dampness and Summer-Heat, as well as transforming Dampness in the Middle Jiao. They are often used for treating abdominal influenza, acute gastritis and hepatitis accompanied by symptoms and signs such as fever, chills, headache and a heavy sensation in the head, fullness in the chest, gastric and hypochondriac regions, reduced appetite, nausea, vomiting, a thick and white tongue coating and a superficial and moderate pulse.

Of these four herbs, Xiang Ru is the warmest. It is able to induce sweating, disperse Wind and Dampness and release the Exterior. It is especially useful when fever, general pain and heaviness of the body are present but there is no sweating. This herb is also called Summer Ma Huang because it has a similar effect to Ma Huang ( Herba ephedrae) in inducing sweating, but is gentler. Xiang Ru is more suitable for use in the summer, when the pores are not closed so tightly as in winter. It has also the function of transforming Dampness in the Middle Jiao and treating abdominal pain, vomiting, diarrhea and edema, but its action is not as strong as that of the other three herbs.

Zi Su Ye is a light and aromatic herb. Since it is less warm and pungent than Xiang Ru, it is not able to induce sweating and disperse Dampness. However, it can gently disperse and expel Wind-Cold in the superficial layer of the body and release the Exterior. It can also stop nausea by soothing the Stomach-Qi. It is an ideal herb for alleviating morning sickness and uneasy sensations in the body during early pregnancy because it can harmonize the Qi in the Nutritive and Defensive levels of the body and soothe the Stomach-Qi, and its action is limited to the Upper Jiao and Middle Jiao.