In spring, when Yang energy rises and growth is abundant, paediatric infectious diseases characterized by exuberance of water and dampness—such as varicella (chickenpox)—become more prevalent.

Varicella is a highly contagious viral illness, primarily transmitted via airborne droplets, but also through direct contact with contaminated clothing or utensils bearing vesicular fluid. Infected children typically experience an acute onset with fever, malaise, reduced appetite, and sometimes upper respiratory symptoms. On the second day of illness, a characteristic rash develops, progressing rapidly from erythematous macules to papules, and then to vesicles and crusts, appearing in successive crops. The vesicles are often oval, variable in size, and surrounded by erythematous halos. Initially, the fluid is clear, later becoming cloudy. In the absence of bacterial superinfection, pustule formation is uncommon. Since lesions do not invade the dermal layer, healing generally occurs without scarring. Pruritus is common at rash onset. With more extensive rash, fever may increase. The entire course typically lasts 4 to 6 days, with a favorable prognosis and the development of lifelong immunity.

Chinese Medicine Etiology and Pathogenesis

In Traditional Chinese Medicine (TCM), varicella is attributed to invasion of externally-contracted epidemic toxin (時行邪毒) in a child with delicate constitution. The pathogen enters via the mouth and nose, accumulating in the lung and spleen systems. The lung governs the skin and exterior, and when its dispersing and descending functions are impaired by pathogenic invasion, symptoms like fever, cough, nasal discharge occur. The spleen governs the muscles, and when toxin combines with internal dampness, it manifests as skin eruptions on the head, face, trunk, and limbs.TCM classifies varicella as a mild pattern of wind-heat with externally contracted toxin, and considers that clearing and venting the pathogen suffices. Clinical observation shows that in most uncomplicated pediatric cases, the disease is self-limiting. Thus, treatment is differentiated into:

🔹 1. Wind-Heat Predominant Pattern (風熱輕證)

Clinical features:

• Mild fever
• Vesicles with red base and clear fluid
• Mild systemic symptoms, calm demeanor

Treatment principle: Disperse wind-heat, clear toxic heat

Recommended formula: Yin Qiao San (銀翹散)
Modified formula:

Administration: Decoction, orally, 1 dose per day.

🔹 2. Heat-Toxin Predominant Pattern (熱毒重證)

Clinical features:

• Dense varicelliform eruption
• Vesicles with turbid fluid and pronounced erythema at the base
• High fever
• Irritability and restlessness

Treatment principle: Clear heat, resolve toxin, protect Yin, and vent eruptions

Recommended formula: Xiao Wei Jie Du Tang (消胃解毒湯)
Modified formula:

If secondary bacterial infection is present (vesicle fluid becomes purulent, rash dark red), add:

• Radix Arnebiae (or Lithospermum) – 紫草 – 5g
• Flos Mume Viride – 綠萼梅 – 6g

Dosage: For children aged 2 to 6 years.
Infants: Use half the dosage.

In Hong Kong, it is common to administer cooling herbal drinks prepared from:

• 紅蘿蔔 (carrot, Daucus carota)
• 竹蔗 (sugarcane stem, Saccharum officinarum)
• 茅根 (rhizoma Imperatae)

These beverages are believed to aid in clearing heat and serve as adjuvant therapy during the febrile phase.