Tadalafil and Clobazam: Can They Be Taken Together?

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What Is Tadalafil and How Does It Work?

Tadalafil is a prescription medicine used to treat erectile dysfunction (ED) in men [3][4]. It belongs to a group of medicines called phosphodiesterase type 5 (PDE5) inhibitors, which also includes sildenafil (Viagra), vardenafil (Levitra), and avanafil (Spedra). Tadalafil works by relaxing the blood vessels in the penis, allowing more blood to flow in when you are sexually aroused. It does not cause an erection on its own—sexual stimulation is still needed [1][4].

Tadalafil is available in two forms: on-demand tablets (usually 10 mg or 20 mg taken at least 30 minutes before sex, with effects lasting up to 36 hours) and daily low-dose tablets (2.5 mg or 5 mg taken every day) [4]. Because tadalafil can lower blood pressure slightly, it is important to tell your prescriber about all other medicines you take, including those for epilepsy, anxiety, or other long-term conditions [4][12].

What Is Clobazam and Why Is It Prescribed?

Clobazam is a benzodiazepine medicine licensed in the UK to treat epilepsy, usually as an add-on treatment to help control seizures [12]. Unlike many other benzodiazepines (such as diazepam or lorazepam), clobazam is used primarily for its anti-epileptic properties rather than for anxiety or sedation, although it can still cause drowsiness and affect coordination.

Clobazam works by enhancing the calming effect of a natural brain chemical called GABA (gamma-aminobutyric acid), which helps to reduce the abnormal electrical activity that causes seizures. Common side effects include drowsiness, dizziness, unsteadiness, and tiredness, especially when you first start taking it or if the dose is increased [12]. Because clobazam can make you feel sleepy or dizzy, it is important to be cautious when combining it with other medicines that may have similar effects.

When to get urgent help

• Erection lasting more than 4 hours (priapism)—go to A&E immediately
• Sudden loss of vision or hearing—seek urgent medical help
• Chest pain during or after sex—call 999
• Severe dizziness, fainting, or collapse—call 999 or go to A&E
• Sudden increase in seizure frequency or severity—contact your epilepsy specialist or GP urgently

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

How Tadalafil and Clobazam May Interact

There is no well-documented major direct interaction between tadalafil and clobazam, and many men take both medicines together without problems. However, both can cause dizziness or light-headedness, and using them at the same time may add to these effects [4][12]. Tadalafil lowers blood pressure slightly, and clobazam can cause drowsiness and unsteadiness; together, this may increase your risk of feeling faint, especially when standing up quickly.

Additionally, clobazam is broken down in the liver by enzymes including CYP3A4, the same enzyme system involved in metabolising tadalafil [4][12]. In theory, clobazam could slightly alter tadalafil levels, though this is not usually clinically significant. Your prescriber will review both medicines during your consultation to ensure the combination is appropriate for you and may advise starting on a lower dose of tadalafil if needed.

What This Means in Plain English

In simple terms, tadalafil and clobazam do not have a dangerous interaction like the one seen with nitrates (which must never be taken with tadalafil). The main concern is that both medicines can make you feel dizzy or unsteady, so you should be careful when moving from sitting to standing, avoid heavy alcohol, and watch for any unusual symptoms. Always declare clobazam (and any other medicines) during your online consultation so the prescriber can tailor the safest treatment plan for you.

What Your Prescriber Will Check Before Approving Tadalafil and Clobazam Together

When you request tadalafil through Cured Pharmacy's online consultation, a UK-registered prescriber will review your full medical history and current medicines, including clobazam [2][4]. They will check that you are not taking any medicines that are absolutely contraindicated with tadalafil, such as nitrates (GTN spray, isosorbide mononitrate), nicorandil, riociguat, or recreational drugs known as 'poppers' [3][4]. These combinations can cause a dangerous drop in blood pressure and must be avoided.

The prescriber will also assess your epilepsy control, any recent changes to your clobazam dose, and whether you experience significant dizziness or drowsiness. If you take other medicines that lower blood pressure (such as alpha-blockers like tamsulosin or doxazosin, or other antihypertensives), the prescriber may recommend starting on the lowest effective dose of tadalafil and monitoring how you feel [4][12]. You should never stop or adjust your clobazam without speaking to the doctor who prescribed it, as this could affect your seizure control.

At a glance

Practical Advice for Using Tadalafil and Clobazam Safely

If your prescriber approves tadalafil while you are taking clobazam, follow these practical steps to minimise any risk. Take tadalafil exactly as prescribed—do not take more than one dose in 24 hours, and do not combine it with another PDE5 inhibitor [4]. Be especially cautious when standing up from sitting or lying down, as the combination may increase dizziness; take your time and hold onto something stable if needed.

Avoid drinking large amounts of alcohol, as this can worsen both erectile dysfunction and dizziness, and may make side effects more likely [1][4]. Grapefruit juice can raise tadalafil levels in the blood, so it is best avoided or limited. If you feel unusually dizzy, faint, or unwell after taking tadalafil, sit or lie down and contact your GP or NHS 111 for advice. Keep both medicines in their original packaging, store them safely out of reach of children, and never share your prescription with anyone else.

When to Seek Medical Advice

Seek urgent medical help (call 999 or go to A&E) if you develop an erection lasting more than four hours (priapism), sudden loss of vision or hearing, or chest pain during sex [3][4]. Contact your GP or epilepsy specialist promptly if you notice any change in your seizure pattern or frequency after starting tadalafil, or if you experience severe dizziness, fainting, or any other concerning symptoms. Do not stop taking clobazam suddenly without medical advice, as this can trigger seizures.

Other Medicines and Lifestyle Factors to Consider with Tadalafil and Clobazam

Beyond clobazam, it is important to tell your prescriber about every medicine you take, including over-the-counter products, herbal remedies, and supplements. St John's wort, a herbal remedy sometimes used for low mood, can reduce tadalafil levels and make it less effective [4]. If you take other anti-epileptic drugs (such as carbamazepine, phenytoin, or phenobarbital), these can also lower tadalafil levels, and your prescriber may need to adjust your dose [4][12].

Lifestyle factors also play an important role in erectile dysfunction and overall health. Smoking, excessive alcohol, lack of exercise, obesity, and poorly controlled diabetes or high blood pressure can all contribute to ED [1][2]. If you have not seen your GP recently about your erectile difficulties, it is a good idea to book an appointment, as ED can sometimes be an early warning sign of heart disease or diabetes [1][2]. Managing these underlying conditions, alongside safe use of tadalafil, offers the best chance of improving your sexual health and quality of life.

Cured Pharmacy's Prescriber-Led Service

At Cured Pharmacy, every prescription for tadalafil (or any other ED treatment) is issued only after a thorough online consultation reviewed by a UK-registered prescriber. You will be asked about your medical history, current medicines including clobazam, and any other health conditions. This ensures that tadalafil is safe and appropriate for you, and that any potential interactions are identified and managed. If you have any questions or your circumstances change, our pharmacy team is here to help—simply contact us for advice.

In summary

• No major direct interaction is reported between tadalafil and clobazam, and many men use both safely.
• Both medicines can cause dizziness; be cautious when standing and avoid heavy alcohol.
• Always declare clobazam and all other medicines during your online consultation.
• Never take tadalafil with nitrates, nicorandil, riociguat, or poppers—this is dangerous.
• Contact your GP if you notice any change in seizure control or severe dizziness.

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