According to TCM theory, infectious diseases are associated with external pathogens attacking the inner body (entering the nutrient and blood stages), individuals may have high fever, a red tongue, bleeding under the skin, or vomiting blood or nose bleeding. Rehmannia root can be used along with figwort root, peony root bark, red peony root and gardenia fruit in the remedies. An overheated digestive track may lead to pass bloody stool, which can be treated with rehmannia root along with golden thread rhizome, garden burnet root, and pagoda tree flower. Bloody urine may be due to damp-heat in the lower burner, which can be treated with rehmannia root combining with couch grass rhizome and field thistle herb. Uterine bleeding can also be a heat sign, in which rehmannia root can be used with baical skullcap root and cattail pollen. In addition, modern TCM often uses rehmannia root in the treatment of low blood platelet count.

After feverish conditions, some individuals may remain a persistent low fever that typically experienced in the evening, a disharmony named as yin deficiency in TCM. Physicians like to prescribe rehmannia root along with sweet wormwood herb, soft-shelled turtle carapace and anemarrhena rhizome for relief. When the individual has constipation or hard stools, then the herb can be used with dwarf lily-turf tuber and figwort root to smooth and lubricate the bowel movements; when there are poor appetite and mouth dryness, the herb can be used with coastal glehnia root, fragrant Solomonseal rhizome and germinated barley to promote the digestive secretions and functions.

Yin deficiency is a common presentation in immune disorders, such as SLE, Sjogren’s syndrome, rheumatoid arthritis, rheumatic fever, erythema nodosum, myocarditis, anaphylactod purpura, IgA nephropathy, urticarial, allergic dermatitis, psoriasis and eczema, which are categorized as consumptive conditions. Other chronic diseases such as hypertension, diabetes, diabetes insipidus, nephritis, hepatitis and asthma are also put in this category. Since individuals usually develop a depleted state, rehmannia root is often prescribed with cornus fruit, Chinese yam, poria, peony root bark, oriental water-plantain rhizome, snakegourd root, Chinese wolfberry, and astragalus root to supplement the body, relieve symptoms, enhance overall functioning and assist the routine treatments.

Fresh rehmannia root is colder in nature that has similar actions as the dried rehmannia root, its yin nourishing actions are weaker, but it has stronger abilities in clearing heat, cooling blood, stop bleeding and promoting body fluid production..