If you take an antidepressant, you might assume that herbal supplements are a safe, natural way to support your wellness. And some of them are. But others can be genuinely dangerous when combined with psychiatric medication – and the risks aren’t always obvious.

The supplement aisle doesn’t come with the same warnings as a pharmacy. Many herbal products interact with SSRIs and SNRIs in ways that can cause serious side effects, reduce your medication’s effectiveness, or even create medical emergencies. Here’s what you need to know before mixing supplements with your antidepressant.

Supplements You Should Avoid

St. John’s Wort is the most important one to know about. It’s completely contraindicated with SSRIs and SNRIs. St. John’s Wort affects the same brain chemicals your antidepressant targets, and combining them can lead to serotonin syndrome – a potentially life-threatening condition caused by too much serotonin activity. Symptoms include agitation, confusion, rapid heart rate, high blood pressure, dilated pupils, muscle twitching, and in severe cases, seizures.

Ma Huang (Ephedra) is a stimulant herb that can raise blood pressure and heart rate. Combined with antidepressants, it increases the risk of cardiovascular side effects and can amplify anxiety symptoms.

Yohimbine is sometimes marketed for energy or sexual health. It can increase norepinephrine levels, and when paired with antidepressants, it may cause dangerous spikes in blood pressure, anxiety, and agitation.

L-Tryptophan is an amino acid precursor to serotonin. Taking it alongside an SSRI is essentially doubling down on serotonin production, which raises the risk of serotonin syndrome.

SAM-e (S-adenosylmethionine) is often sold as a mood supplement. Like L-tryptophan, it increases serotonin activity and should not be combined with SSRIs or SNRIs without medical supervision.

Ginseng can interact with antidepressants by affecting serotonin and other neurotransmitter systems. It may increase the risk of side effects and is generally best avoided while on psychiatric medication.

Supplements That Are Generally Safer

Not all supplements are off-limits. Some have a better safety profile when combined with most antidepressants, though you should still discuss any supplement with your provider before starting:

Valerian is commonly used for sleep and relaxation. It generally has a low interaction risk with antidepressants, though it can enhance sedation.

Melatonin is one of the most widely used sleep supplements and is generally considered safe with most antidepressants.

Lavender (particularly in oral supplement form like Silexan) has shown promise for mild anxiety and has a relatively low interaction profile.

Passionflower is used for anxiety and sleep and is generally well-tolerated alongside SSRIs, though it may increase drowsiness.

Milk thistle is primarily used for liver support and typically doesn’t interact significantly with antidepressants.

Supplements That Increase Bleeding Risk

This is a category many people don’t think about. SSRIs already carry a mild increased risk of bleeding because serotonin plays a role in platelet function. Adding supplements that also thin the blood can compound this risk.

If you take an SSRI and have additional bleeding risk factors – such as taking blood thinners, having a clotting disorder, or undergoing surgery – be especially cautious with ginkgo biloba, garlic supplements, ginger (in high doses), turmeric/curcumin, policosanol, and saw palmetto. These supplements can all increase bleeding risk on their own, and the combination with SSRIs amplifies the concern.

The Bottom Line

“Natural” doesn’t mean “safe with everything.” Your antidepressant is doing important work in your brain, and introducing supplements that affect the same systems can undermine that work or create new risks.

The simplest rule: always tell your prescriber about every supplement you take, and always check before starting something new. A quick conversation can prevent a serious problem.

Your antidepressant is helping you. Make sure your supplements aren’t working against it.