Valerian is often presented as a “natural sleep aid” for mild anxiety and sleep disorders. However, “natural” does not mean “risk-free”: valerian does have side effects, and certain combinations (alcohol, sedatives, some medications) can increase drowsiness or cause problems. In this guide, you will understand what adverse effects are possible, who should avoid valerian, and how to use it more safely (dosage, duration, driving, surgery, interactions).

What are the side effects of valerian?

Most common side effects (and what to expect)

At usual doses, valerian is often well tolerated, but side effects may occur, including:

• Drowsiness (sometimes a “hangover” in the morning, especially at high doses)
• Headaches (cephalalgia)
• Digestive problems : stomach aches, nausea , abdominal pain
• Dizziness
• Less commonly: heart problems/ palpitations , confusion, agitation, paradoxical insomnia in some people

A “paradoxical” effect: when valerian stimulates instead of calming

Although it may seem counterintuitive, some people report:

• agitation, nervousness,
• insomnia,
• excitement.

This “paradoxical” profile is described among the reported effects.

Drowsiness and decreased alertness: the key safety point

This is the effect to take most seriously on a daily basis: valerian can decrease attention, especially:

• if you increase the dose,
• if you combine it with alcohol/sedatives,
• if you are sensitive.

Consequence: avoid driving or operating machinery after taking it.

Valerian: dangers and contraindications (who should avoid it?)

Pregnancy and breastfeeding: maximum caution

As a precaution, use is not recommended during:

• pregnancy,
• breastfeeding.

Children

Valerian is generally not recommended for young children .

Liver: caution if there is a history of or treatment with hepatotoxic substances

• In case of liver problems, or if you are taking substances that may be toxic to the liver, extra caution is advised.
• Liver toxicity has been observed in some reported cases.

Safety advice : If you have liver disease, high transaminases, or are undergoing "heavy" liver treatment, avoid self-medication and seek medical advice.

Drug interactions: what should not be combined with valerian?

The main mechanism: additive sedative effects

Valerian may prolong or enhance the effects of other central nervous system depressants, with a risk of:

• significant drowsiness,
• decreased reflexes,
• confusion,
• accidents (driving).

Table: High-risk interactions (most important)

Plants and supplements: cumulative sedative and/or hepatic effect

Valerian can increase the effects of other sedative plants and also increase the toxic effects on the liver of certain plants.

Examples: St. John's wort , kava , etc.

Valerian and surgery/anesthesia: when to stop?

Valerian may increase sedation when used with anesthetics.

Recommendations for stopping before intervention:

• Stop 2 weeks before surgery (according to some recommendations).
• or at least one week before surgery (according to other recommendations).

Practical approach : if an operation is planned, inform the anesthesiologist and aim for a stoppage in advance ( 1 to 2 weeks ) depending on the context.

Duration of use, habituation and stopping: what you need to know

Short-term use: the safest rule

The reported uses and recommendations converge towards short courses of treatment :

• often 2 to 6 weeks ,
• Prolonged use beyond 6 weeks may cause insomnia.
• Avoid exceeding 1 month without medical supervision.

Withdrawal/symptoms upon discontinuation (if used for a long time)

Withdrawal symptoms have been described with prolonged use, including:

• tachycardia, irritability, anxiety,
• palpitations , agitation, delirium.

Tip : if you have been taking it for a long time, prefer a gradual stop rather than an abrupt stop (and get it checked if you are taking any other medication).

How to limit side effects: a checklist for “safe” use

7 simple (pragmatic) rules

1. Start low (minimum dose of the product) and observe for 2–3 nights.
2. Avoid alcohol on the evening of taking it.
3. Do not combine with sedatives/anxiolytics/sleeping pills without advice.
4. No driving/machinery if drowsy (including the next day).
5. Limit the duration (short course of treatment).
6. If symptoms persist, do not "increase the doses" indefinitely: consult a doctor.
7. Before surgery, stop and inform the team.

Warning signs: stop and seek advice quickly

• “Unmanageable” drowsiness or confusion
• severe dizziness / falls
• unusual palpitations
• worsening of insomnia
• Signs suggesting a liver problem (unusual severe fatigue, dark urine, jaundice) → medical emergency

Valerian side effects FAQ

Can valerian cause drowsiness the next day?

Yes. Some people feel drowsy in the morning , especially at high doses .

What are the most common side effects of valerian?

The most commonly reported side effects include headaches , stomach aches/nausea , dizziness , and sometimes drowsiness or insomnia in some people.

Which medication should not be taken with valerian?

sedative medications (sleeping pills, tranquilizers, certain antidepressants, antiepileptics, neuroleptics, opioids, H1 antihistamines), as the risk of drowsiness increases.

Is it safe to drink alcohol while taking valerian?

This is not recommended: alcohol can increase sedation and decrease alertness.

Is valerian not recommended during pregnancy?

Yes, as a precaution it is not recommended during pregnancy and breastfeeding .

Should valerian be stopped before an operation?

Yes: it can increase sedation with anesthesia. Some recommendations suggest stopping it 1 to 2 weeks before surgery, depending on the case.

Conclusion

The side effects of valerian are usually mild (drowsiness, headaches, digestive problems, dizziness), but the risks increase significantly when combined with alcohol or sedatives , as well as in the context of surgery or liver problems. For safe and effective use, remember: short course , minimum effective dose , no alcohol , and consultation with a pharmacist/doctor if you are currently taking other medications or have underlying health conditions.