Many animal experiments show that Prunella vulgaris can cause adverse reactions. The ethanol extract of Prunella vulgaris can inhibit the cellular and humoral immune responses in mice. Subcutaneous injection can obviously reduce thymus and spleen and increase adrenal gland. Intraperitoneal injection can significantly increase the plasma cortisol level and reduce the number of peripheral blood lymphocytes. All these indicate that Prunella vulgaris may be an immunosuppressant, and long-term or large-scale administration will inhibit the immune function of the body.
In addition, taking the water extract of Prunella vulgaris can significantly increase the values of serum alanine aminotransferase and serum asparagine aminotransferase in mice, indicating that Prunella vulgaris also has hepatotoxicity. Clinically, it has been reported that children died of acute severe hepatitis after taking Chinese herbal medicines containing Xanthium sibiricum, Prunella vulgaris and Endothelium Corneum Gigeriae Galli for 3 months, and it has also been reported that taking Prunella vulgaris caused allergies, manifested as itchy skin, papules and even fainting due to anaphylactic shock.
Some experts have studied Prunella vulgaris and published a paper devoted to the pharmacological problems of Prunella vulgaris. The article does mention that Prunella vulgaris has anti-inflammatory and immunosuppressive effects. However, it should be noted that this is the pharmacological action of Prunella vulgaris, not an adverse reaction. It cannot be simply considered that its immunosuppressive effect is equivalent to "long-term or large-scale administration can inhibit the immune function of the body", and there is no necessary connection between the two.
Moreover, some doctors have also conducted animal experiments on the toxicity of Prunella vulgaris, and found that the use of Prunella vulgaris in mice is ten times more than the normal amount, and no obvious adverse reactions have been found.
So there is no definite evidence that Prunella vulgaris is "toxic". Of course, there are reports that Prunella vulgaris can cause allergies and liver damage, but there is no definite evidence to prove that the statement that Prunella vulgaris is toxic is far-fetched.
Be sure to pay attention to the weight when using Prunella vulgaris. If we can't handle it ourselves, we should ask the doctor and use it according to the doctor's advice, so as to use it correctly and avoid adverse effects on our health.