Can I take Sedoxil and Venlafaxine together?
Drug interaction guide
Originally published 25 Jan 2026
Meets Patient’s editorial guidelines
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Taking these two medicines together can make you feel very sleepy, dizzy, or confused. It can also make it harder to concentrate or perform tasks that require alertness, such as driving. In some cases, it may cause breathing to become slower or shallower.
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Why this happens
Both Sedoxil (mexazolam) and venlafaxine have effects on the central nervous system. Sedoxil is a benzodiazepine that slows down brain activity to reduce anxiety, while venlafaxine is an antidepressant that can also have sedative effects. When used together, their calming effects on the brain are added together (an additive effect).
What you should do
Back to contentsYou should use this combination with caution. Avoid driving or operating heavy machinery until you know how these medicines affect you. Do not drink alcohol while taking these medications, as it will make the sleepiness much worse. If you feel excessively drowsy or have trouble breathing, contact your doctor immediately.
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Important precautions
Back to contentsDepression and anxiety disorders
Venlafaxine can cause an increase in suicidal thoughts or self-harm, particularly when first starting treatment or changing doses. Patients and caregivers must monitor for any changes in mood or behaviour.
Drowsiness and coordination
Sedoxil causes significant drowsiness and affects your coordination. Do not drive or operate machinery until you know how it affects you. The effect is much stronger if you drink alcohol.
Dependence and withdrawal
Sedoxil can be addictive if used for more than a few weeks. Do not stop taking it suddenly, as this can cause serious withdrawal symptoms like tremors or seizures.
Severe Respiratory Insufficiency or Sleep Apnoea
Sedoxil is a benzodiazepine that can suppress breathing. It must be avoided if you have severe lung disease, chronic obstructive pulmonary disease (COPD), or sleep apnoea, as it may lead to dangerous respiratory failure.
Serotonin Syndrome
When taken with other serotonergic medicines, venlafaxine can cause serotonin syndrome, a potentially life-threatening condition. Seek immediate medical help if you experience agitation, hallucinations, fast heartbeat, or severe muscle stiffness.
Bleeding disorders
Venlafaxine increases the risk of serious bleeding, especially if you are taking aspirin, NSAIDs (like ibuprofen), or blood thinners (like warfarin). Seek medical advice if you notice unusual bruising or bleeding.
Food and drink warnings
Back to contentsAlcohol
It is best to avoid or strictly limit alcohol while taking these medicines. Combining alcohol with Sedoxil or Venlafaxine can significantly increase drowsiness, dizziness, and the risk of breathing difficulties. It may also worsen the side effects of your medication and impair your coordination.
Grapefruit juice
Avoid drinking grapefruit juice or eating grapefruit while taking Sedoxil. Grapefruit contains compounds that slow down the breakdown of this medicine in your body, which can lead to dangerously high levels of the drug in your bloodstream and increase the risk of side effects.
Caffeine (Coffee, tea, energy drinks)
Limit your intake of caffeine. Caffeine is a stimulant that can counteract the calming effects of Sedoxil. Additionally, both caffeine and Venlafaxine can increase your heart rate and blood pressure; combining them may lead to jitteriness, palpitations, or anxiety.
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Using other medicines
Back to contentsTaking multiple medicines? Our Medicines Interaction Checker helps you check whether your prescriptions, over-the-counter medicines, and supplements are safe to take together. Simply search for your medicines to see potential interactions and what to do about them.
Disclaimer
This information is for general educational purposes only and should not be relied upon as a substitute for professional medical advice. Always consult your GP, pharmacist, or another qualified healthcare professional before making decisions about your medications. Individual circumstances may vary, and only a healthcare professional who knows your medical history can provide personalised guidance.
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Article history
The information on this page is written and peer reviewed by qualified clinicians.
25 Jan 2026 | Originally published

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