Valerian and medicine interactions: what to know

Yes, valerian can interact with certain medicines, but the evidence is weak and, in most cases, the risk is theoretical. There are no robust studies confirming serious interactions, but there are reasons for caution, especially with sedatives, anxiolytics, and anticoagulants. If you take any medication regularly, the safest option is to talk to your doctor or pharmacist before using valerian. This article explains what is known, what is speculation, and where the limits of current knowledge lie.

What is valerian and how does it work?

Valerian (Valeriana officinalis) is a plant used for centuries to promote sleep and relieve tension. Its active compounds, such as valerenic acid and valepotriates, appear to interact with gamma-aminobutyric acid (GABA) in the brain. GABA is the main inhibitory neurotransmitter, and increasing its activity tends to calm the nervous system. That is why valerian is often compared to mild sedative medications.

But be careful: the way valerian works is not fully understood. Some studies suggest it increases GABA availability, others point to effects on specific receptors. What is certain is that the effect is generally mild and may take a few weeks to appear, if it appears at all. Clinical evidence for insomnia is mixed, and many trials show no difference from placebo. This matters for interactions: if the effect is uncertain, the risk is also difficult to predict.

Which interactions are most concerning?

The most frequently cited interactions involve medications that also act on the GABA system or have a sedative effect. The logic is simple: if two compounds depress the central nervous system, the combined effect can be additive, causing excessive drowsiness, dizziness, or difficulty concentrating. However, clinical evidence for these interactions is scarce. There are no large-scale documented cases, but the theoretical risk exists.

Sedatives and anxiolytics (benzodiazepines, zolpidem, etc.)

Medicines such as diazepam, lorazepam, alprazolam, or zolpidem are used for anxiety and insomnia. Combining them with valerian may potentiate the sedative effect. Some case reports describe excessive sedation when they are combined, but there are no controlled trials. If you already take a sedative, adding valerian without supervision is not a good idea. Your doctor can adjust doses if necessary.

Antidepressants

Selective serotonin reuptake inhibitors (SSRIs), such as fluoxetine or sertraline, are widely prescribed. The interaction with valerian is poorly studied. Some experts warn of a theoretical risk of serotonin syndrome, but there are no confirmed cases. Other antidepressants, such as tricyclics, may also have a sedative effect, and the sum with valerian could increase drowsiness. Again, prudence recommends talking to your doctor.

Blood pressure medications

Valerian may have a slight hypotensive effect, meaning it can lower blood pressure. In theory, combined with antihypertensives, it could cause drops in blood pressure, with dizziness or fainting. But the evidence is anecdotal. If you take blood pressure medication, monitor your blood pressure and inform your doctor.

Anticoagulants and antiplatelet agents

Here the risk is more serious. Valerian may interfere with blood clotting, although the mechanisms are not clear. There are reports of increased effect of anticoagulants such as warfarin, which could lead to bleeding. If you take warfarin, apixaban, clopidogrel, or high-dose aspirin, do not use valerian without medical advice. This is one of the interactions with the greatest potential for real harm.

What about medicines metabolised in the liver?

Many medicines are processed by liver enzymes, especially cytochrome P450. Valerian may inhibit or induce some of these enzymes, altering the concentration of the medicine in the blood. For example, valerian may inhibit CYP3A4, which metabolises numerous drugs, including some statins, antifungals, and immunosuppressants. If the medicine stays in the body longer, the risk of side effects increases. But again, studies are limited and results are contradictory. Do not assume it is safe just because you have not seen warnings on the label.

Can you take valerian with medicines? What the evidence says

We do not know for certain. The evidence is weak and based on few studies and case reports. For most medicines, the risk of a clinically relevant interaction is probably low. But "probably low" is not "zero". And there are exceptions, such as anticoagulants, where the risk may be higher. If you take chronic medication, especially for heart, blood pressure, clotting, or mental health, valerian is not a harmless product you can add on your own.

What to do if you want to take valerian while on medication

Do not stop any medication on your own initiative. Do not start valerian without first asking your doctor or pharmacist. Take a list of your medicines, including over-the-counter and supplements, and ask specifically about valerian. The professional can check for any known contraindications and advise on dose and duration. If you already take valerian and are about to start a new medicine, tell the doctor about the plant.

If you experience excessive drowsiness, dizziness, irregular heartbeat, or any unusual symptom after taking valerian with another medicine, seek medical help. Better still: avoid the combination until you have professional advice.

At-risk groups: pregnant women, the elderly, and children

Pregnant or breastfeeding women should not use valerian, as there are no safety data. Older people are more sensitive to sedative effects and the risk of falls, and often take multiple medicines; interaction may be more likely. Children should not take valerian without paediatric advice. In these groups, the recommendation is clear: do not use without medical supervision.

What valerian does not do (and why that matters)

Some people seek valerian to replace medicines for anxiety or insomnia. That is not advisable. Valerian is not a potent anxiolytic, nor does it have an effect comparable to benzodiazepines. If you have a mental health problem, treatment should be decided by a professional. Using valerian to "wean off" a medicine can be dangerous. And do not expect valerian to resolve chronic insomnia; the effect, when it exists, is modest. If your goal is better sleep, there are other approaches with more evidence, such as sleep hygiene.

Interactions with alcohol and other substances

Alcohol is a central nervous system depressant. Combining valerian with alcohol can increase drowsiness and impair coordination. The same applies to other supplements with a sedative effect, such as melatonin or passionflower. Although there are no specific studies, prudence suggests avoiding these combinations, especially if you are going to drive or operate machinery.

What studies actually show

There are no large-scale clinical trials on valerian interactions. What exists are case reports, animal studies, and limited pharmacokinetic analyses. For example, one study in healthy volunteers showed that valerian did not significantly affect the metabolism of a test drug, but the results are not generalisable. Other studies suggest possible enzyme inhibition, but with contradictory data. In short, the evidence base is insufficient to state safety or danger. This means the decision should be conservative: when you do not know, assume the risk.

Frequently asked questions about valerian and medicines

Can I take valerian with paracetamol or ibuprofen?

There are no known interactions with common painkillers. The risk is low, but if you take these medicines regularly, it is a sign that you have a condition that deserves medical attention, and valerian should not be your priority.

What about antibiotics?

There are no documented interactions. However, some antibiotics affect the gut flora, and valerian may have gastrointestinal effects. If you feel discomfort, talk to your pharmacist.

Can I take valerian with the contraceptive pill?

There is no evidence of interaction. But if you are on the pill, you are probably young and healthy; there is no reason for concern, but keep the rule of informing your doctor about all supplements.

Does valerian interact with thyroid medicines?

There are no data. The thyroid is sensitive to various substances, and the medicines have a narrow therapeutic margin. If you take levothyroxine, for example, it is prudent to separate the valerian dose by a few hours, although there is no official recommendation. Talk to your doctor.

What to do now: a simple plan

If you want to try valerian, do it with information. First, check whether you have any health condition that contraindicates its use. Second, make a list of your medicines and supplements. Third, take that list to your doctor or pharmacist and ask directly: "Can I take valerian with these medicines?" If the professional says there is no problem, start with a low dose and observe how you feel. If you feel any strange effect, stop and talk to them. Remember that valerian is not a magic solution for sleep; it is a plant with modest and uncertain effects. Your health is more important than a supplement. And if your goal is better sleep, consider lifestyle changes first, such as regular schedules, less screen time at night, and a comfortable sleeping environment. These measures have more evidence than any plant.