Tadalafil and Gabapentin: Can You Take Them Together?

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Tadalafil and Gabapentin: Understanding the Interaction

Published: 21 October 2026

Many men prescribed gabapentin for nerve pain or epilepsy wonder whether tadalafil and gabapentin can be taken together safely. The good news is that no major direct interaction between these two medicines is commonly reported in clinical practice. However, both medicines can affect blood pressure and cause dizziness, so your prescriber will carefully review your full medication list and medical history during your consultation to ensure tadalafil is appropriate for you.

What Is Tadalafil and How Does It Work?

Tadalafil is a prescription medicine used to treat erectile dysfunction (ED) in men [4]. 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. Tadalafil is the generic version of the branded medicine Cialis and is available in two forms: on-demand tablets (10mg or 20mg taken at least 30 minutes before sex, with effects lasting up to 36 hours) and daily low-dose tablets (2.5mg or 5mg taken once a day) [4].

Unlike some other ED treatments, tadalafil's long duration of action means you don't need to time it as precisely before sexual activity. However, it still requires sexual stimulation to work—it won't cause an erection on its own [1]. Tadalafil is only available on prescription in the UK after a clinical assessment by a registered prescriber, who will check your medical history, current medicines, and whether any conditions make it unsuitable for you [2].

What Is Gabapentin and Why Is It Prescribed?

Gabapentin is a prescription medicine primarily used to treat epilepsy and neuropathic pain (nerve pain caused by conditions such as diabetes, shingles, or spinal cord injury). It works by affecting the way nerves send messages to your brain, helping to reduce pain signals and prevent seizures. Gabapentin is also sometimes prescribed for other conditions, including restless legs syndrome and certain types of anxiety, though these are off-label uses.

Common side effects of gabapentin include dizziness, drowsiness, tiredness, and unsteadiness, particularly when you first start taking it or when the dose is increased. These effects can be more pronounced if you also take other medicines that affect the central nervous system or blood pressure. Gabapentin does not directly affect erectile function, but some men report changes in sexual desire or performance as a side effect, though this is not common.

Can Gabapentin Affect Erectile Function?

While gabapentin is not known to cause erectile dysfunction directly, any medicine that causes drowsiness, dizziness, or fatigue may indirectly affect sexual performance or desire. If you have noticed changes in your erections since starting gabapentin, it is worth discussing this with your GP, as the underlying condition being treated (such as nerve pain or anxiety) may also contribute to ED [1]. Your doctor can review your treatment and explore whether adjustments or additional support, such as ED medication, might help.

Tadalafil and Gabapentin: Is There an Interaction?

No major direct pharmacological interaction between tadalafil and gabapentin is commonly reported in clinical practice or major drug interaction databases. This means that the two medicines do not significantly affect each other's levels in the body or how they work. However, both medicines can cause side effects that may overlap, particularly dizziness and a drop in blood pressure, so caution is still needed [3][4].

Tadalafil can lower blood pressure slightly, especially when you first start taking it or if you are also on other blood-pressure-lowering medicines. Gabapentin can cause dizziness and drowsiness, which may be more noticeable if your blood pressure drops. For this reason, your prescriber will ask about all your current medicines, including gabapentin, during your consultation to assess whether tadalafil is safe and appropriate for you. They may recommend starting on a lower dose of tadalafil or monitoring for side effects more closely.

It is important never to take tadalafil with nitrates (such as GTN spray or isosorbide mononitrate), nicorandil, riociguat, or recreational drugs known as 'poppers', as these combinations can cause a dangerous fall in blood pressure [4]. Gabapentin is not in this category, so the combination with tadalafil is not contraindicated, but individual assessment is essential.

What Your Prescriber Checks Before Approving Tadalafil

When you request tadalafil through Cured Pharmacy, a UK-registered prescriber will review your online consultation to ensure the treatment is safe for you. They will check your full list of current medicines, including gabapentin, to identify any potential interactions or contraindications. They will also ask about your medical history, including heart conditions, blood pressure, liver or kidney problems, and any history of stroke, as these can affect whether tadalafil is suitable [2][4].

If you take gabapentin, the prescriber will pay particular attention to whether you experience dizziness or low blood pressure, as these side effects may be more noticeable when combined with tadalafil. They may recommend starting with a lower dose of tadalafil (such as 10mg on-demand or 2.5mg daily) and advising you to monitor how you feel, especially when standing up quickly. If you are also taking other medicines that lower blood pressure, such as alpha-blockers or antihypertensives, the prescriber will assess the overall risk and may adjust your treatment plan accordingly [3][4].

Declaring All Your Medicines

It is essential to list every medicine you take during your consultation, including prescription medicines, over-the-counter treatments, herbal remedies, and supplements. Even if you think a medicine is unrelated to ED, it may interact with tadalafil or affect your suitability for treatment. For example, potent CYP3A4 inhibitors (such as ritonavir, ketoconazole, or clarithromycin) can raise tadalafil levels in your blood, requiring dose adjustments, while CYP3A4 inducers (such as rifampicin or St John's wort) can make tadalafil less effective [4]. Your prescriber will check every medicine you declare to ensure your safety.

Practical Advice for Taking Tadalafil and Gabapentin Together

If your prescriber approves tadalafil while you are taking gabapentin, there are a few practical steps you can take to minimise the risk of side effects. First, take tadalafil exactly as prescribed—do not take more than the recommended dose or take it more frequently than once a day (for on-demand tablets) or once a day (for daily tablets). If you are starting tadalafil for the first time, your prescriber may suggest a lower dose initially to see how you tolerate it [4].

Be aware of the potential for dizziness, especially when standing up quickly or after drinking alcohol. Both tadalafil and gabapentin can contribute to this, so take your time when getting up from sitting or lying down, and avoid heavy alcohol consumption, which can worsen dizziness and make ED worse [1]. If you feel dizzy, lightheaded, or unwell after taking tadalafil, sit or lie down until the feeling passes, and contact your GP or pharmacist if it persists.

Do not stop or change your gabapentin dose without speaking to your doctor, even if you experience side effects. Gabapentin must be reduced gradually to avoid withdrawal symptoms or seizures if you take it for epilepsy. If you have concerns about how your medicines are working together, contact your prescriber or GP for advice rather than making changes on your own.

When to Seek Urgent Medical Help

While serious side effects from tadalafil are rare, you should seek urgent medical help if you experience an erection lasting more than four hours (priapism), as this can cause permanent damage if not treated promptly [4]. You should also seek immediate help if you have sudden loss of vision or hearing, severe chest pain during sex, or symptoms of a severe allergic reaction (such as swelling of the face, lips, or throat, or difficulty breathing).

If you feel very dizzy, faint, or unwell after taking tadalafil, especially if you are also taking gabapentin or other medicines that affect blood pressure, stop what you are doing, sit or lie down, and seek medical advice. If you are unsure whether your symptoms are serious, contact NHS 111 for guidance or call 999 if you feel your condition is life-threatening. Always keep your prescriber or GP informed of any new or worsening symptoms, as they can review your treatment and make adjustments if needed [2].

Reporting Side Effects

If you experience side effects from tadalafil or gabapentin, you can report them to your prescriber, GP, or pharmacist. You can also report side effects directly to the Medicines and Healthcare products Regulatory Agency (MHRA) via the Yellow Card scheme at www.mhra.gov.uk/yellowcard. Reporting side effects helps regulators monitor the safety of medicines and improve patient care.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 21 October 2026]
2. National Institute for Health and Care Excellence. (n.d.). Erectile dysfunction. Clinical Knowledge Summaries. https://cks.nice.org.uk/topics/erectile-dysfunction/ [accessed 21 October 2026]
3. Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 21 October 2026]
4. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 21 October 2026]

Information on this page is for educational purposes only and is not medical advice. Prescription treatments require clinical assessment by a UK-registered prescriber. Always consult a qualified healthcare professional before starting or changing any medication.