Tadalafil and Memantine: Can They Be Taken Together?
Learn whether these medicines interact and what your prescriber checks during a UK pharmacist-led consultation.
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Tadalafil and Memantine: Understanding the Interaction
Published: 23 October 2026
If you're taking memantine for dementia and considering tadalafil for erectile dysfunction, you may wonder whether tadalafil and memantine can be taken together safely. The good news is that no major interaction is commonly reported between these two medicines, but your prescriber will still need to review your full medical history and current medications during a consultation. This page explains what each medicine does, what checks are needed, and practical advice for using tadalafil alongside memantine.
At a glance
What is tadalafil and memantine used for?
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 [3][4]. Tadalafil is available as the branded medicine Cialis or as a generic version, and it can be taken either on-demand (10mg or 20mg at least 30 minutes before sexual activity, with effects lasting up to 36 hours) or as a daily low-dose tablet (2.5mg or 5mg) [4].
Memantine is a prescription medicine used to treat moderate to severe Alzheimer's disease and other forms of dementia. It works by regulating the activity of glutamate, a chemical messenger in the brain involved in learning and memory. Memantine does not cure dementia but may help slow the worsening of symptoms and improve daily functioning in some people. It is usually started at a low dose and gradually increased over several weeks.
Both medicines are taken by mouth, and many men with dementia also experience erectile dysfunction—either as part of ageing, underlying health conditions such as diabetes or heart disease, or as a side effect of other medications. Understanding how tadalafil and memantine work together is important for safe and effective treatment.
Is there an interaction between tadalafil and memantine?
No major interaction is commonly reported between tadalafil and memantine. These two medicines work through different mechanisms in different parts of the body: tadalafil acts on blood vessels (primarily in the penis), while memantine acts on receptors in the brain. They are not known to interfere with each other's effectiveness or to cause a significant increase in side effects when used together [3][4].
However, it is still essential that your prescriber knows about all the medicines you take, including memantine, before prescribing tadalafil. This is because erectile dysfunction treatment requires a full review of your cardiovascular health, blood pressure, and any other conditions or medications that might affect the safety of PDE5 inhibitors. Memantine itself does not make tadalafil unsafe, but the underlying condition (dementia) and any other medicines you take for related health problems must be considered.
Your prescriber will check that tadalafil is suitable for you and that sexual activity is safe given your overall health. If you have any concerns about taking tadalafil and memantine together, discuss them openly during your consultation—your prescriber is there to ensure the combination is right for you.
How the combination is assessed
During your online consultation at Cured Pharmacy, you will be asked about all your current medicines, including memantine, and any medical conditions you have. The prescriber will review whether tadalafil is safe for you, paying particular attention to your heart health, blood pressure, and any medicines that are known to interact dangerously with PDE5 inhibitors (such as nitrates, nicorandil, or riociguat). Because memantine does not fall into any of these high-risk categories, the focus will be on your overall suitability for ED treatment rather than a specific concern about the memantine itself.
What your prescriber checks before prescribing tadalafil
Before tadalafil can be prescribed, your doctor or pharmacist prescriber will assess whether it is safe and appropriate for you. This includes checking your cardiovascular health, because sexual activity itself places demands on the heart, and tadalafil can lower blood pressure slightly [4]. You will be asked about any history of heart attack, stroke, angina, heart failure, abnormal heart rhythms, very low or very high blood pressure, and whether you have been advised to avoid sexual activity.
You will also be asked about all the medicines you currently take. Tadalafil must never be taken with nitrates (such as GTN spray, isosorbide mononitrate, or isosorbide dinitrate), nicorandil, riociguat, or recreational drugs known as 'poppers' (amyl or alkyl nitrites), because the combination can cause a dangerous drop in blood pressure [3][4]. If you take alpha-blockers for an enlarged prostate or high blood pressure (such as tamsulosin or doxazosin), you may still be able to use tadalafil, but you must be stable on the alpha-blocker and will usually start on the lowest dose of the ED medicine.
Other medicines that can affect tadalafil levels include potent CYP3A4 inhibitors (such as ritonavir, ketoconazole, itraconazole, or clarithromycin), which may require a lower dose of tadalafil, and CYP3A4 inducers (such as rifampicin, carbamazepine, phenytoin, or St John's wort), which can make tadalafil less effective [4]. Your prescriber will review all these factors, including memantine, to ensure the treatment is safe for you.
What you need to know
- No major interaction is commonly reported between tadalafil and memantine—they can usually be taken together safely.
- Your prescriber will review all your medicines and health conditions to ensure tadalafil is suitable for you.
- Never take tadalafil with nitrates, nicorandil, riociguat, or poppers—this combination is dangerous.
- Seek urgent help for an erection lasting over 4 hours, sudden vision or hearing loss, or chest pain during sex.
- Cured Pharmacy offers tadalafil from £7.95 (£6.36 first order with code Ednew) after an online consultation.
Practical advice for taking tadalafil with memantine
If your prescriber approves tadalafil, you can take it alongside memantine without needing to separate the doses or adjust the timing of either medicine. Tadalafil can be taken with or without food, though a very large or high-fat meal may delay how quickly it works. Memantine is usually taken once or twice a day, and you can continue your usual schedule.
Keep in mind that tadalafil only works when you are sexually aroused—it does not cause an automatic erection. On-demand tadalafil (10mg or 20mg) should be taken at least 30 minutes before sexual activity, and its effects can last up to 36 hours, giving you flexibility. Daily tadalafil (2.5mg or 5mg) is taken at the same time each day and allows for spontaneity without needing to plan ahead [4].
Avoid drinking large amounts of alcohol when using tadalafil, as alcohol can make erectile dysfunction worse and increase the risk of dizziness or low blood pressure. Grapefruit juice can raise tadalafil levels in the blood and should be avoided. If you experience any new or unusual symptoms after starting tadalafil—such as dizziness, chest pain, or changes in vision—stop taking the medicine and seek medical advice. Do not stop or change your memantine dose without speaking to your doctor, as this is an important treatment for your dementia.
Monitoring and follow-up
Once you start tadalafil, pay attention to how you feel, especially in the first few doses. If you notice any side effects such as headache, indigestion, back pain, or flushing, these are usually mild and temporary. If side effects are troublesome or do not settle, contact your prescriber—they may suggest a lower dose or a different ED medicine. Continue to attend regular reviews with your GP or specialist for your dementia and any other health conditions, and always mention that you are using tadalafil so that your overall treatment plan can be coordinated.
Side effects and warning signs with tadalafil and memantine
Tadalafil is generally well tolerated, but common side effects include headache, indigestion, back pain, muscle aches, flushing, and a blocked or runny nose [4]. These effects are usually mild and go away on their own. Memantine can cause side effects such as dizziness, headache, constipation, drowsiness, or confusion, though many people tolerate it well. When taking both medicines, be aware of how you feel overall, particularly if you experience dizziness, as both medicines can occasionally affect balance or alertness.
Seek urgent medical help (call 999 or go to A&E) if you experience an erection lasting more than four hours (priapism), sudden loss of vision in one or both eyes, sudden decrease or loss of hearing, or chest pain during or after sexual activity. These are rare but serious side effects that require immediate attention [3][4]. If you develop chest pain during sex, do not take nitrate medicines (such as GTN spray) to relieve it if you have used tadalafil in the past 48 hours, as this combination is dangerous—call 999 instead.
If you notice any worsening of your dementia symptoms, increased confusion, or any other new symptoms after starting tadalafil, speak to your GP or specialist. While tadalafil and memantine are not known to interact, any change in your health should be reviewed by a healthcare professional to ensure your treatment remains safe and appropriate.
When to get urgent help
- An erection lasting more than 4 hours (priapism)—call 999 or go to A&E immediately
- Sudden loss of vision in one or both eyes—stop tadalafil and seek urgent medical help
- Sudden decrease or loss of hearing, sometimes with ringing in the ears or dizziness—stop tadalafil and see a doctor urgently
- Chest pain during or after sexual activity—call 999; do not take nitrate medicines if you have used tadalafil in the past 48 hours
- Severe dizziness, fainting, or signs of a severe allergic reaction (swelling of face, lips, or throat, difficulty breathing)—call 999
Call 999 or go to A&E in an emergency, or contact NHS 111 for urgent advice.
Getting tadalafil from Cured Pharmacy
Cured Pharmacy is a GPhC-registered online pharmacy (GPhC 9012511) offering a range of erectile dysfunction treatments, including tadalafil, following an online consultation with a UK-registered prescriber. You will be asked about your medical history, current medicines (including memantine), and any conditions that might affect the safety of ED treatment. If tadalafil is suitable for you, your prescription will be dispensed by our pharmacy team and delivered discreetly to your door.
We offer both generic and branded tadalafil at transparent prices. Generic tadalafil is available from £7.95 (or £6.36 for your first order with code Ednew), Tadalafil 20mg (Teva) from £9.99 (£7.99 with code Ednew), Avarante (tadalafil) 10mg from £11.49 (£9.19 with code Ednew), and branded Cialis from £12.00 (£9.60 with code Ednew). All prices include the consultation, prescription, and delivery. You can also choose from other ED medicines such as sildenafil, vardenafil, or avanafil if they are more suitable for you.
If you have any questions about taking tadalafil with memantine or any other aspect of your treatment, our pharmacy team is here to help. Erectile dysfunction is common and treatable, and we are committed to providing safe, effective, and confidential care. If you have not seen a GP about your erectile dysfunction before, we encourage you to do so, as ED can sometimes be an early sign of underlying health problems such as heart disease or diabetes [1][2].
Why choose Cured Pharmacy?
Cured Pharmacy combines the convenience of online ordering with the expertise of UK-registered pharmacists and prescribers. Every prescription is reviewed individually to ensure it is safe and appropriate for you, taking into account all your medicines and health conditions. We offer clear pricing, fast delivery, and ongoing support, so you can access the treatment you need with confidence and discretion.
Taking both medicines together
You do not need to separate tadalafil and memantine—take them at whatever times suit you. Always tell your prescriber about all your medicines, including memantine, so they can ensure tadalafil is safe for you.
Scientific References
- NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 23 October 2026]
- National Institute for Health and Care Excellence. (n.d.). Erectile dysfunction. Clinical Knowledge Summaries. https://cks.nice.org.uk/topics/erectile-dysfunction/ [accessed 23 October 2026]
- Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 23 October 2026]
- Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 23 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.
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Your Questions Answered
Can I take tadalafil if I'm on memantine for Alzheimer's disease?
Yes, no major interaction is commonly reported between tadalafil and memantine, but you must complete an online consultation so a prescriber can review your full medical history and all current medicines to ensure tadalafil is safe for you.
Do I need to take tadalafil and memantine at different times of day?
No, you do not need to separate the doses. You can take tadalafil and memantine at whatever times suit you, as they do not interfere with each other.
Will memantine make tadalafil less effective?
No, memantine is not known to reduce the effectiveness of tadalafil. The two medicines work through different mechanisms and do not interfere with each other's action.
What should I tell my prescriber if I'm taking memantine?
Tell your prescriber that you take memantine, what dose you are on, and list all your other medicines and medical conditions. This helps them assess whether tadalafil is safe and suitable for you.
Are there any medicines I must not take with tadalafil?
Yes, do not take tadalafil with nitrates (GTN spray, isosorbide mononitrate/dinitrate), nicorandil, riociguat, or poppers (amyl/alkyl nitrites), as the combination can cause a dangerous drop in blood pressure.
Can tadalafil cause confusion or affect my memory?
Tadalafil is not known to cause confusion or memory problems. If you notice any worsening of your dementia symptoms or increased confusion after starting tadalafil, speak to your GP or specialist.
How long does tadalafil last, and how should I take it?
On-demand tadalafil (10mg or 20mg) lasts up to 36 hours and should be taken at least 30 minutes before sexual activity. Daily tadalafil (2.5mg or 5mg) is taken once a day at the same time and allows for spontaneity.
What should I do if I get side effects from tadalafil?
Common side effects like headache or indigestion are usually mild and temporary. If side effects are troublesome, contact your prescriber—they may suggest a lower dose or a different ED medicine. Seek urgent help for an erection lasting over 4 hours, sudden vision or hearing loss, or chest pain.
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Medically reviewed by
Tarun Kumar, Superintendent Pharmacist (GPhC 2233073)