St John’s Wort Side Effects: 8 Reactions and Who Must Avoid It

An Overview of St John’s Wort Side Effects

St John’s wort is generally well tolerated in short-term studies, and its reactions are usually milder than those of older antidepressants. Still, St John’s wort side effects do happen, and some groups of people should not take it at all. Here are 8 reactions to know and clear rules on when to stop.

Common St John’s Wort Side Effects

1. Sun sensitivity

Hypericin can make the skin and eyes more sensitive to sunlight, causing a rash or burns more easily, especially in fair-skinned people and at high doses. In Egypt’s strong sun, use sunscreen, wear a hat and sunglasses, and avoid tanning beds. The Solaray and Nature’s Way labels both warn against prolonged sun or UV exposure.

2. Stomach upset

Nausea, indigestion or loose stools can occur. Taking the capsules with a meal, as the Solaray label suggests, often helps.

3. Dry mouth

Mild dry mouth is reported. Drink water regularly through the day.

4. Dizziness

Some people feel light-headed, so be careful when driving until you know how you react.

5. Insomnia, restlessness and anxiety

The herb can be stimulating. Take the last dose in the afternoon rather than at bedtime.

6. Headache and tiredness

These usually ease after the first weeks. If they persist, stop and ask your doctor.

Serious St John’s Wort Side Effects

7. Mania in bipolar disorder

In people with bipolar disorder, the herb may trigger mania or hypomania: very little sleep, racing thoughts and risky behaviour. It should not be used by anyone with a personal or family history of bipolar disorder without a psychiatrist.

8. Drug interaction effects

The most dangerous problems come from interactions, such as serotonin syndrome with antidepressants or contraceptive failure. These are explained in full in St John’s wort interactions.

Who Must Avoid It?

• Pregnant and breastfeeding women, as safety has not been established.
• Children and teenagers.
• People with bipolar disorder or severe depression.
• Anyone on prescription medicines, especially MAO inhibitors, unless a doctor approves.
• People scheduled for surgery: stop at least two weeks beforehand, since it can interact with anaesthetic drugs.

When to Stop and Seek Help

• A widespread rash or blistering after sun exposure.
• Agitation, fever, sweating and tremor (possible serotonin syndrome).
• Very elevated mood, no need for sleep or racing thoughts.
• Worsening low mood or any thoughts of self-harm, which need urgent medical or emergency care.

Never treat depression on your own. Read our depression and anxiety guide to recognise warning signs.

How to Reduce St John’s Wort Side Effects

• Follow the label dose: Solaray St. John’s Wort 325 mg 180 and Solaray 325 mg 100 are 1 capsule three times daily with a meal or water.
• Nature’s Way St. John’s Wort 700 mg is 2 capsules twice daily, used for at least two months for best results.
• Do not take more than the label says; higher doses raise sun sensitivity.
• Take doses with food and earlier in the day.
• Protect your skin from the sun.

Stopping suddenly after long use can occasionally cause mild dizziness or irritability, so ask your doctor about tapering. To understand what it may and may not do, read St John’s wort benefits.

Frequently Asked Questions About St John’s Wort Side Effects

Does it cause weight gain?

Weight gain is not a typical reaction, unlike some prescription antidepressants.

Does it affect sexual function?

Sexual side effects seem less common than with SSRIs, but they have been reported.

Are St John’s wort side effects worse with long use?

Long-term safety data are limited, so regular review with your doctor is wise.

Do St John’s wort side effects go away after stopping?

Most mild reactions such as stomach upset, dry mouth or sun sensitivity fade within days of stopping, but the effect on other medicines can last about two weeks.

Can I reduce St John’s wort side effects by taking a lower dose?

Sometimes, but do not adjust the dose without advice, and never use the herb to treat depression on your own.

Is it safe for older adults?

Older adults usually take several medicines, so the interaction risk is higher. Always ask a pharmacist first.

Conclusion

Most St John’s wort side effects are mild: sun sensitivity, stomach upset, dry mouth, dizziness, insomnia and headache. The serious risks are mania in bipolar disorder and drug interactions. It is not for pregnancy, nursing, children or the weeks before surgery. If your doctor agrees, Solaray 180, Solaray 100 and Nature’s Way 700 mg are available at No Style Like Pharmacy.

This article was reviewed by the No Style Like pharmacy content team. It is for general awareness only and does not replace advice from your doctor or pharmacist.

Stop the product and contact your doctor if you notice any unusual reaction. For more information see the NCCIH St. John’s wort page.