St John’s Wort for PMDD


St. John’s Wort

St John’s Wort or as it is known by its latin name, Hypericum Perforatum, is a plant native to North America and has been used in herbal medicine traditionally  for a variety of ailments but often thought of as a treatment for mood conditions like anxiety or depression. 

Mechanism of Action

The difference in looking into herbal medicine vs pharmaceutical medicine is that when a drug is developed, we know exactly what is in the drug. It is generally formulated to work on a specific pathway in the body. With herbal medicine we are looking at a whole plant. A plant that can have literally thousands of constituents and active ingredients. Some that we understand how they work, and others that we may not understand. So we need to look at research studies with caution when they are looking at plant medicine. Have they extracted what they ‘think’ is the active ingredient from that plant and studied just that part? Are they looking at the plant as a whole? The complexity of plants lends to the synergy in which they work in the body, but it can make studying them with our Western approaches to analysis, very difficult.

Holistic View of St John’s Wort

St John’s Wort has been used for thousands of years for a variety of conditions. With respect to PMDD, St John’s Wort holds interest because we know that the plant affects the way mood balancing neurotransmitters like serotonin, dopamine and adrenaline are used in the brain. In animal trials we are also seeing that other phytochemicals found in St John’s wort affect the calming pathways in the brain (GABA pathways). And recently we are seeing that St John’s Wort can activate different genes involved in mood regulation. 

This is very exciting when we consider that PMDD is thought to be a condition where serotonin and dopamine utilization are affected. We also know that stress worsens PMDD symptoms. So balancing adrenaline and stress response would be a benefit to treat PMDD.


In most studies, St. John's wort extract was standardized to 0.3% hypericin content and used at doses of 300 mg 3 times daily. Some studies have used St. John's wort extract standardized to 0.2% hypericin at doses of 250 mg twice daily. St. John's wort extract standardized to 5% hyperforin has been used at doses of 300 mg 3 times daily.

Work with a certified practitioner to determine what dosage is best for you.

Preliminary Trials

Preliminary trials of using St John’s Wort in treating PMDD and the early results have been positive. The trials that were done were small and not over a long period of time, knowing that St John’s Wort may have the ability to shift how genes are being expressed, these changes will take some time to fully take effect. More research and longer trials are needed to see more potential benefits.


St John’s Wort is very well tolerated, and tends to have a smaller side effect profile then other pharmaceuticals. St John’s Wort interact with other medications because of the effect it has on the liver. This means that you need to talk to a health care professional before starting St. John’s Wort if you’re taking any medication or prior to starting medication if you’re taking St. John’s Wort.

St John’s Wort may reduce the effectiveness of other medications you are taking (including the birth control pill, which is often used to treat PMDD), which is why it is always best to have a health care team to work with so that you can be guided through the process of discovering what will work best for you.

So this summer, keep your eye out for this beautiful yellow flowered plant, it is powerful medicine!

Katie Bigras