by Chris Westerley

Created on: March 02, 2010

Interactions between herbal and other medicines can kill. Millions in the USA live with this silent threat. This article reviews the ways in which herbal remedies interact with other medicines and considers three popular remedies in more detail: St John’s wort, ginkgo biloba and ginseng.  

=Herbal remedies are widely used=

A review (February 2010) by

Mayo Clinic cardiologists claims Americans consult alternative health practitioners more frequently than their primary care physicians and spend $30 billion/year on alternative therapies, with herbal remedies accounting for a significant proportion. Wallace Sampson, Stanford University, estimates up to 30% of Americans use herbal remedies and similar preparations.

Herbal remedies are classed by the FDA as dietary supplements and are freely available for self-medication. Many think herbs are “natural” and therefore gentler than conventional medicines. Nevertheless, many herbs have potent activity, which can affect  other medicines .

=Interactions: examples=

Additive:  Valerian is used to help sleep.  If taken with other sedatives, the overall sedative effect is increased. Over-sedation can slow down breathing dangerously. Valerian should not be used with sleeping pills, benzodiazepines, barbiturates and anticonvulsants. It also increase effects of anesthesia and should not be taken near to surgery.

Opposing:  Echinacea stimulates immunity. It antagonizes medicines, such as azathioprine and methotrexate, given to suppress the immune response. This may cause symptoms of autoimmune diseases such as lupus to be insufficiently controlled. Transplant recipients, who have to take immunosuppressants for life, risk the transplant being rejected if immunosuppression decreases.

Increased susceptibility: Evening primrose makes it easier for seizures to be triggered. Phenothiazines used in schizophrenia are associated with a risk of seizures. Evening primrose increases this risk. Epileptics may find their usual dose of medication no longer prevents seizures.

Complex metabolic interactions: Some unchanged drugs are active, others must form active metabolites. Herbal remedies can affect metabolism by:

- inducing enzyme activity, resulting in faster drug metabolism;

-inhibiting enzyme activity, resulting in slower drug metabolism;

-competing for an enzyme, making less available to metabolize a drug.

Depending on the properties of the other medicine, active drug levels in the body can be:

• 1
• 2
• Next Page >>