Welcome to Bad Science on the Internet! Here, we highlight some of the crazy  and sometime dangerous stuff people post online, then give you the facts.  

The Bad Science: St. John’s Wort as a treatment for Depression

What do they claim? Suggested uses include the treatment of depression, anxiety, boosting the immune system to fight infections, among many other potential indications

Are they trying to sell you something? A bottle of supplements will cost you about ten dollars.

Is any of this true? St. John’s Wort is an extract of Hypericum perforatum. A typical extract contains over 150 different chemicals isolated from the plant, most of which aren’t known to do anything for humans. Any potential activity of this extract is believed to come from a few classes of compounds (the naphthodianthrones, the phloroglucinols, and the chemical hypericin) which make up a very small percent of the total dose of the extract. St John’s Wort has a long history of use as an herbal remedy, mainly for depression and anxiety. There is ample literature demonstrating some degree of anti-depressive and anti-inflammatory actions. For depression, the evidence is spotty – some studies have shown benefit, while others have shown none or less than standard anti-depressant drugs.  In truth, St. John’s Wort might have had a future as a first line option for mild forms of depression had it not been for…

Is any of this dangerous? This is where things get tricky.

St. John’s Wort is not particularly toxic.  It can cause gastrointestinal effects (abdominal pain or diarrhea) and dizziness or headaches, but these are pretty rare and minor.  It’s actually fairly toxic to grazing animals (cattle, sheep, etc), but if you’re reading this blog, I’m guessing you are not a horse.

The main issue with St. John’s Wort is how it interacts with other medications. St. John’s Wort induces (increases the production and activity of) several enzymes in your body whose job it is to metabolize drugs. There are a lot of things that can induce these enzymes, but St. John’s Wort is a particularly strong inducer and induces specific subtypes (mainly cytochrome P450 3A4, 2D2 and 2C19 and p-glycoprotein) that are responsible for metabolizing many important drugs. What effects could this have? It can almost completely inhibit the effects of warfarin, a common anti-coagulant used to prevent heart attacks and strokes. It will inactivate digoxin, which is used to treat congestive heart failure in very sick patients, and will also basically render that statins (commonly used to reduce cholesterol) useless. It also interferes with the metabolism of oral contraceptives, making them much less effective (yikes!). St. John’s Wort will compromise the efficacy of many heartburn medications (proton pump inhibitors), numerous pain killers and anesthetics (including ibuprofen and opiates), some antibiotics and anti-virals, blood pressure medications, and a number of anti-cancer agents, among many others.

But wait, there is more! Most of the promising research on St. John’s Wort is for the treatment of depression, and here it can cause significant drug interactions too. It can interact with serotonin re-uptake inhibitors (SSRIs) to cause severe adverse reactions. It can inhibit the effects of benzodiazepines (like Xanax),  tricyclic anti-depressants, and clozapine as well. Depression is a difficult disease to treat, and many patients will take a combination of these types of drugs – all of which may be effected by St. John’s Wort. By interfering with the activity of these medications,  St. John’s Wort may lead to a dangerous lack of efficacy or potential side effects.

What’s the bottom line?  Taking St. John’s Wort isn’t nearly as unusual as some of the other topics we’ve covered – Ozone therapy for example. But while the benefits are debatable, the real problem is that most people don’t know the potential risks of using St. John’s Wort in combination with other treatments. Drug interactions can be very serious. If you are taking St. John’s Wort, or thinking of doing so, please talk to your doctor if you are currently on any other medications. The ones on the list above are just examples, and there are many more that could be affected by this supplement. St. John’s Wort is not an approved treatment for depression, but if you still want to give it a try, you may not want to do so without first consulting your doctor, especially if you’re taking other medications.

Some references:

http://umm.edu/health/medical/altmed/herb/st-johns-wort

http://onlinelibrary.wiley.com/doi/10.1002/ptr.5050/abstract