A Quick Look at Herbal Supplements and Prescription Drug Interactions

 to severe bleeding in several case studies.
  
Patients with HIV regularly used St. John’s wortPatients who regularly take Zoloft or Paxil should stay
to ease depression until just recently when it wasaway from St. John’s wort that is marketed as
found that St. John’s wort dramatically reduceda substitute for prescription antidepressant drugs. 
blood levels of Crixivan.  Crixivan is an important HIVPeople on Xanax or Valium for anxiety should not
drug and protease inhibitor.  At the low levels oftake kava, an herb marketed as a relaxant.
concentration, AIDs patients are likely to become 
resistant to Crixivan.Of course there are arguments from the Herbal
 product makers who say their herbs are extremely
The Food & Drug Administration began to alertsafe and that claims to the contrary are unfounded
doctors and request that Merck, the maker ofand cause unnecessary fears. 
indinavir, add a warning about St. John’s wort to 
the drug’s label.Consumers should realize that herbal supplements
 work much like drugs.  Many people are leary of
There are as many as 40% of adults in the U.S. whotaking drugs prescribed by their doctor and will ask
regularly use herbs, vitamins, and other supplementsprobing questions, then venture onto the local
and about 15 million take prescription drugs at thehealth-food store where a high-school diploma person
same time.  Many of these people never tell theirwill say, “Take this to ease your headaches,”
doctors of the mixtures.and they immediately say “Okay,” and
 purchase the product.  People have the general idea
There are no wide-ranging clinical trials definitely linkingthat if something is labeled as being “natural,”
herbal supplements to interactions with drugs,this means it is a safe product and
however, several case studies from the past 30“prescription” could mean something toxic for
years suggest many interactions may exist.  Leadingthem.
herbal supplements that may interact negatively with 
prescription drugs include:The problems with identifying herb-drug interactions
 include:
- St. John’s wort 
- Melatonin·        There is a general lack of knowledge
- Kavaabout dangerous interactions
- Garlic·        Product labels on herbal supplements
- Garlic extractsusually are not helpful
 ·        The FDA does not push drug
St. John’s wort may also interact with an arraycompanies to investigate herb-drug interactions
of prescription drugs because it is broken down by·        Herbal product makers are not required
an enzyme that also metabolizes about half ofto advertise possible adverse reactions
existing over-the-counter and prescription drugs. ·        Under federal law, herbal products do
There is some evidence that St. John’s wortnot need to prove safety and efficacy
reduces levels of:·        Herbal product makers do not need to
 conform to good manufacturing practices
- Lanoxin (digoxin) a drug that treats congestive 
heart failureThe PDA does plan to establish standards for herbal
- Coumadin (warfarin), a blood thinnerproduct manufacturers.
- Bronchodilator drugs for asthma 
- Tegretol (carbamazepine), an anticonvulsantExperts recommend:
  
In addition to drug interactions, some herbal products- Consumers, particularly those taking prescription
appear to be addictive, which intensifies the effectdrugs for chronic conditions, should consult a doctor,
of certain drugs.  The most worrisome are a fewherbalist, or pharmacist about possible interactions
popular herbal products such as:before taking any kind of supplement
  
- GarlicSource:  Alger A. Dangerous Cocktail: Herbals and
- GinkgoDrugs. Business Week [serial online]. May 08,
 2000;2:E12. Available from: MAS Ultra - School Edition,
The use of garlic and ginkgo appear to increase theIpswich, MA. Accessed August 17, 2008.
effect of the blood thinner Coumadin, which has led