Tadalafil and Diazepam: Can You Take Them Together?

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Key takeaways

• Tadalafil and diazepam can usually be taken together safely with no major direct interaction
• Both medicines can lower blood pressure and cause dizziness, so prescribers assess your individual risk
• Always declare all current medicines during your consultation, including diazepam
• Limit alcohol, stand up slowly, and contact your GP if you experience severe dizziness or other side effects
• Prescription treatments are only supplied after a clinical assessment by a UK-registered prescriber

What is tadalafil and how does it work?

Tadalafil is a prescription medicine used to treat erectile dysfunction (ED) in men. It belongs to a group of medicines called PDE5 inhibitors, which work by relaxing blood vessels in the penis, allowing increased blood flow when you are sexually aroused [4]. Tadalafil is the active ingredient in branded Cialis and is also available as a generic medicine.

Tadalafil can be taken in two ways: on-demand (10 mg or 20 mg taken at least 30 minutes before sexual activity, with effects lasting up to 36 hours) or daily (2.5 mg or 5 mg taken once a day at the same time, allowing for spontaneity) [4]. It only works when you are sexually stimulated and does not increase sexual desire on its own.

Common side effects include headache, indigestion, back pain, muscle aches, flushing, and nasal congestion [4]. These are usually mild and temporary. Tadalafil is not suitable for everyone, particularly men taking nitrates, nicorandil, riociguat, or those with certain heart conditions [1][4].

What is diazepam and what is it used for?

Diazepam is a benzodiazepine medicine prescribed for short-term relief of severe anxiety, muscle spasms, seizures (fits), or to help with alcohol withdrawal symptoms. It works by enhancing the effect of a natural calming chemical in the brain called GABA (gamma-aminobutyric acid), which reduces excessive activity in the nervous system.

Diazepam is usually prescribed for short periods (typically 2–4 weeks for anxiety) because it can cause dependence if used for longer. Common side effects include drowsiness, tiredness, muscle weakness, dizziness, and confusion, especially in older adults. It can also slow your reactions and impair your ability to drive or operate machinery safely.

Because diazepam affects the central nervous system and can cause drowsiness and low blood pressure, it is important that your prescriber knows you are taking it before starting any new medicine, including treatments for erectile dysfunction. Never stop diazepam suddenly without medical advice, as this can cause withdrawal symptoms.

Why men with anxiety may experience ED

Anxiety and erectile dysfunction often occur together. Performance anxiety, stress, and worry can interfere with sexual arousal and make it difficult to achieve or maintain an erection [1][10]. Some men are prescribed diazepam or other benzodiazepines to manage anxiety symptoms, but these medicines themselves can sometimes contribute to sexual difficulties, including reduced libido or delayed ejaculation.

If you are experiencing both anxiety and ED, it is important to discuss both concerns with your GP or prescriber. Treating the underlying anxiety—through talking therapies, lifestyle changes, or medication—can often improve erectile function. Your prescriber will consider the best approach for your individual situation.

At a glance

Can you take tadalafil and diazepam together?

Yes, tadalafil and diazepam can usually be taken together, as there is no major direct drug interaction between them. However, both medicines can cause side effects that may add together, particularly dizziness, drowsiness, and a drop in blood pressure [3][4]. This means you may feel more light-headed or unsteady than you would with either medicine alone.

Your prescriber will assess your full medical history, current medicines, and overall health before approving the combination. They will consider factors such as your blood pressure, heart health, kidney and liver function, and whether you are taking any other medicines that might interact. It is essential to declare all medicines you are taking—including over-the-counter medicines, herbal remedies, and recreational drugs—during your consultation.

If your prescriber approves the combination, they may recommend starting tadalafil at a lower dose to minimise the risk of side effects. You should avoid drinking large amounts of alcohol, as this can worsen dizziness and make erectile dysfunction worse [1][4]. If you experience severe dizziness, fainting, or any other concerning symptoms, contact your GP or pharmacist for advice.

How tadalafil and diazepam may affect blood pressure

Both tadalafil and diazepam can lower blood pressure, although they do so through different mechanisms. Tadalafil relaxes blood vessels throughout the body (not just in the penis), which can cause a mild drop in blood pressure [4]. Diazepam, by calming the nervous system, can also reduce blood pressure and cause dizziness, particularly when you stand up quickly (orthostatic hypotension).

When taken together, these effects may add up, increasing the risk of feeling dizzy, light-headed, or faint, especially when moving from sitting or lying down to standing. This is usually manageable, but it is important to be aware of the possibility. If you are also taking other medicines that lower blood pressure—such as antihypertensives, alpha-blockers, or nitrates—the risk is higher, and some combinations are not safe [3][4].

To reduce the risk of dizziness, stand up slowly from sitting or lying positions, avoid sudden movements, and limit alcohol intake. If you feel faint or experience a significant drop in blood pressure, sit or lie down immediately and seek medical advice if symptoms do not improve quickly.

What your prescriber will check

During your online consultation at Cured Pharmacy, the prescriber will review your current medicines, including diazepam, and check for any contraindications or interactions. They will ask about your blood pressure, heart health, kidney and liver function, and any other medical conditions. They will also confirm that you are not taking nitrates, nicorandil, riociguat, or recreational drugs such as poppers, as these are dangerous when combined with tadalafil [3][4].

The prescriber may recommend a lower starting dose of tadalafil if you are taking diazepam or other medicines that affect blood pressure. They will also provide personalised advice on timing, alcohol, and what to do if you experience side effects. This careful assessment ensures that the combination is as safe as possible for you.

Practical advice for taking tadalafil and diazepam safely

If your prescriber approves the combination of tadalafil and diazepam, follow their instructions carefully. Take each medicine exactly as prescribed, and do not increase the dose without consulting your prescriber. If you are taking tadalafil on-demand, plan ahead and take it at least 30 minutes before sexual activity; if you are on daily tadalafil, take it at the same time each day [4].

Be cautious with alcohol, as it can worsen dizziness and make erectile dysfunction worse. Heavy drinking also increases the risk of side effects from both medicines [1][4]. Avoid grapefruit juice, as it can raise tadalafil levels in your blood and increase the risk of side effects. Do not take tadalafil with any other erectile dysfunction medicine or with nitrates, nicorandil, riociguat, or poppers [3][4].

If you experience dizziness, stand up slowly and avoid sudden movements. If you develop a severe headache, chest pain during sex, an erection lasting more than four hours, or sudden loss of vision or hearing, seek urgent medical help. Keep all your medicines in their original packaging, store them safely, and never share them with others. If you have any questions or concerns, contact the Cured Pharmacy team or your GP for advice.

When to see your GP about erectile dysfunction and anxiety

If you are experiencing erectile dysfunction for the first time, it is important to see your GP for a full assessment. ED can be an early warning sign of underlying health conditions such as heart disease, diabetes, or high blood pressure [1][2]. Your GP can arrange blood tests, check your cardiovascular health, and discuss treatment options, including lifestyle changes, talking therapies, and prescription medicines.

If you are taking diazepam for anxiety and are also experiencing ED, talk to your GP about both concerns. Anxiety and ED often occur together, and treating the underlying anxiety can sometimes improve erectile function [1][10]. Your GP may recommend cognitive behavioural therapy (CBT), counselling, or other psychological support alongside or instead of medication.

At Cured Pharmacy, our online consultation is designed to assess your suitability for tadalafil and other ED treatments, but it is not a substitute for a full GP assessment, especially if you have new or worsening symptoms. Our UK-registered prescribers will review your medical history and current medicines, including diazepam, to ensure that tadalafil is safe and appropriate for you. All prescription medicines are only supplied after a clinical assessment by a qualified prescriber.

Getting help from Cured Pharmacy

Cured Pharmacy is a GPhC-registered online pharmacy (GPhC 9012511) offering discreet, convenient access to erectile dysfunction treatments. Our online consultation is reviewed by a UK-registered prescriber, who will check your medical history, current medicines (including diazepam), and overall health to ensure that tadalafil or another ED medicine is safe for you.

We offer a range of ED treatments, including generic and branded options, at transparent prices. Your medicine is dispensed by our UK-based pharmacy team and delivered discreetly to your door. If you have any questions about tadalafil and diazepam or any other aspect of your treatment, our pharmacists are here to help.

When to get urgent help

• An erection lasting more than 4 hours (priapism)—go to A&E immediately
• Sudden loss of vision or hearing—stop tadalafil and seek urgent medical help
• Severe dizziness, fainting, or chest pain during sex—call 999 or go to A&E
• Allergic reaction (swelling of face, lips, tongue, or throat, difficulty breathing)—call 999 immediately

Call 999 or go to A&E in an emergency, or contact NHS 111 for urgent advice.

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