St. John’s Wort is a highly popular herbal remedy for anxiety and depression but it isn’t without side effects or contraindications. Often taken internally as a tea, tincture, or in pill form, herbalists use it for a great deal of ailments because of the numerous healing benefits. While St. John’s Wort is an effective tool, it does tend to interact with a large number of Western medications. In most cases, St. John’s wort drug interactions decreases the effectiveness of the medication which can cause serious health issues. In other cases however, St. John’s wort may increase the effects of a medication which can lead to severe issues or even possibly death.
The contraindications of St. John’s Wort makes it very important for you to know what you can and can not take if you plan on taking the herb.
Medications
If you are taking any of the following medications, you should not use St. John’s Wort. (Please note that this may not be a complete list and you should follow up with a properly trained professional.)
If you are presently taking antidepressants, St. John’s Wort may possibly interact with these medications, increasing side effects that can lead to a very dangerous condition called serotonin syndrome. These medications would include:
- Tricyclic antidepressants including Amitriptyline (Elavil), nortryptyline (Pamelor), or imipramine (Tofranil)
- SSRIs, and monoamine oxidase inhibitors (MAOIs) including Phenelzine, (Nardil), or tranylcypromine (Parnate)
- Citalopram (Celexa)
- escitalopram (Lexapro)
- fluvoxamine (Luvox) paroxetine (Paxil), fluoxetine (Prozac), sertraline (Zoloft)
If you take medication for allergies and take prescriptions antihistamines, St. John’s wort may reduce the levels of these drugs in the body making them less effective. It is important not to take antihistamines with St. John’s Wort herb including:
- Loratadine (Claritin)
- Cetirizine (Zyrtec)
- Fexofenadine (Allegra)
Digoxin, which is taken as a heart medication, is not to be used with St. John’s wort as the St. John’s wort may decrease levels of the Digoxin and reduce its effectiveness.
St. John’s wort can reduces the effectiveness of immuno suppressing medications. When these medicines are taken after an organ transplant or to control autoimmune diseases, it is important not to interfere with the drugs effectiveness. There have been reports of certain blood levels dropping and the transplanted organ being rejected by the body. The popular immuno suppressant drugs are below, but others could be prescribed.
- Adalimumab (Humira)
- Azathioprine (Imuran)
- Cyclosporine
- Etanercept (Enbrel)
- Tacrolimus (Prograf)
St. John’s Wort herb seems to interact with at least two kinds of medicati

ons that are used to treat HIV and AIDS patients. Drugs that are used to fight HIV, and AIDS are called protease inhibitors and non-nucleoside reverse transcriptase inhibitors. When HIV infects a CD4 cell in the body, it copies its own genetic code into the cell’s DNA. The cell is then creates new copies of HIV virus. NNRTIs, also known as “non-nucleosides” or “non-nukes” for short, attach themselves to reverse the process and prevent the enzyme from converting RNA to DNA. This prevents the HIV virus genetic code from getting into the healthy genetic material of the cell and helps stop the cell from producing a new virus. These drugs help to keep the immune system in balance. It is best not to use St. John’s Wort with any antiretroviral medications.
Stay clear of St. John’s Wort if you taking any form of birth control. There have been reports of women having breakthrough bleeding while using the herb. It may be possible that the herb interferes with the effectiveness of the birth control pills leading to unwanted or unplanned pregnancies.
Animal studies have shown that St. John’s Wort can interfere with the high blood pressure medications such as Reserpine. The herb can cause a decrease in the way the body uses these medications, and can cause health issues, and other unwanted side effects. Stay clear of St. John’s if you taking medicine for high blood pressure.
If you are taking other sedative medications, for either anxiety or stress, St. John’s wort may increase the effect of drugs that have a sedating effect. Medications such as barbiturates, Benzodiazepines such as alprazolam (Xanax), and diazepam (Valium) should not be used in conjunction with St. John’s Wort.
Drugs to treat insomnia such as zolpidem (Ambien), zaleplon (Sonata), eszopiclone (Lunesta), and ramelteon (Rozerem) should also not be used while taking St. John’s wort. St. John’s Wort increases the effect of the medication, and an overdose can occur.
If you are taking anticonvulsant medications such as phenytoin (Dilantin) and valproic acid (Depakote) for seizures, it is best to stay clear of the herb St. John’s Wort. The herb interacts and can make the medicine less effective causing harmful health issues.
For those who suffer from asthma, emphysema, chronic bronchitis or other COPD disorder, and are taking theophylline, you should not take St. John’s Wort. The herb can reduce levels of this medication in the blood causing severe health issues.
Medications to treat migraines called Triptans, should not be taken if using St. John’s wort. The herb can increase the risk of the side effects of the medication, including serotonin syndrome. These migraine medications include drugs such as:
- Naratriptan (Amerge)
- Rizatriptan (Maxalt)
- Sumatriptan (Imitrex)
- Zolmitriptan (Zomig)
If you are taking blood thinning medications, such as Warfarin (an anticoagulant drug), St. John’s wort will reduce it’s effectiveness. By taking both the herb and the drug this would increase the chance of sudden heart attack, stroke, or death.
St. John’s wort is broken down by certain liver enzymes. Due to this fact, it may interact with other drugs that are broken down by the same liver enzymes. Those drugs may include:
Drugs that are used as antifungal medications such as ketoconazole (Nizoral), itraconazole (Sporanox), fluconazole (Diflucan)
Statins, a famous drug that is used to lower cholesterol is also broken down by the liver. Other medications that are broken down by the liver are calcium channel blockers, used to lower blood pressure. Users of these types of medication should also avoid St. John’s Wort.
If you are taking any medications, including to but not limited to the ones that are listed here, it is best to talk to your health care provider before taking St. John’s Wort. Many doctors don’t understand herbs and all their components, so finding a herbalist, or someone well versed in herbs may also be helpful in your health care decisions.
Other St. John’s Wort Interactions
Alcohol – Do not take drink alcoholic beverages when using St. John’s Wort.
Certainly do your homework regarding your lifestyle including diet and herbal teas to see if St. John’s Wort will interact. Whether you choose to use St. John’s Wort internally for anxiety and depression, or externally for aches and pains, the side effects would be the same. Remember, the skin is our largest organ, and if you are applying St. John’s Wort Oil to you skin, it is being absorbed into your body. Continue to check as new research is always happening and results are published. St. John’s Wort is a very powerful and effective herb when used correctly and as you’ve read, potentially disastrous when used carelessly.