Tadalafil and Lisdexamfetamine: Can You Take Them Together?

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Key takeaways

• Tadalafil and lisdexamfetamine have no direct chemical interaction but both affect your heart and blood pressure.
• Your prescriber will check your cardiovascular health before approving tadalafil if you take lisdexamfetamine.
• Report chest pain, dizziness, palpitations, or fainting to a doctor promptly.
• Take each medicine exactly as prescribed and avoid heavy alcohol.
• Cured Pharmacy offers tadalafil from £7.95 after a UK prescriber reviews your consultation.

What is tadalafil and lisdexamfetamine?

Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed to treat erectile dysfunction [3][4]. It works by relaxing blood vessels in the penis, allowing increased blood flow when you are sexually aroused. Tadalafil is available as on-demand tablets (10 mg or 20 mg taken at least 30 minutes before sex, with effects lasting up to 36 hours) or as a daily low dose (2.5 mg or 5 mg) for continuous support [4]. It is the generic form of Cialis and requires a prescription after a clinical assessment.

Lisdexamfetamine (brand name Elvanse in the UK) is a central nervous system stimulant prescribed for attention deficit hyperactivity disorder (ADHD) [12]. It is converted in the body to dexamfetamine, which increases levels of dopamine and noradrenaline in the brain, improving focus and impulse control. Because it is a stimulant, lisdexamfetamine can raise heart rate and blood pressure, and it carries warnings about cardiovascular risk, particularly in people with pre-existing heart conditions [12].

Both medicines are prescription-only. Tadalafil is supplied by Cured Pharmacy after an online consultation reviewed by a UK prescriber; lisdexamfetamine is typically prescribed by a specialist psychiatrist or ADHD clinic and dispensed through your usual pharmacy.

Do tadalafil and lisdexamfetamine interact directly?

There is no major pharmacokinetic interaction between tadalafil and lisdexamfetamine—that is, neither medicine significantly alters how the other is absorbed, broken down, or eliminated from the body [3][4][12]. Lisdexamfetamine does not inhibit or induce the liver enzyme CYP3A4, which metabolises tadalafil, so the blood levels of tadalafil remain predictable when both are taken together.

However, both medicines can affect your cardiovascular system. Tadalafil causes mild vasodilation (widening of blood vessels), which can lower blood pressure slightly [4]. Lisdexamfetamine, as a stimulant, typically increases heart rate and blood pressure [12]. In most people these effects are modest and may even counterbalance each other to some extent, but the combination does place extra demand on the heart and circulation.

For this reason, the key concern is not a direct drug–drug interaction but rather the cumulative cardiovascular load. Your prescriber will need to confirm that your heart and blood vessels are healthy enough to handle both the stimulant effect of lisdexamfetamine and the physical exertion of sexual activity while taking tadalafil [2][4]. This is particularly important if you have any history of high blood pressure, heart disease, stroke, or irregular heartbeat.

Why cardiovascular health matters

Sexual activity itself increases heart rate and blood pressure temporarily, much like moderate exercise [2]. When you add a PDE5 inhibitor such as tadalafil (which can cause a small drop in blood pressure) and a stimulant such as lisdexamfetamine (which can raise blood pressure and heart rate), your cardiovascular system must cope with competing demands [4][12]. Most men tolerate this well, but anyone with underlying heart problems, uncontrolled high blood pressure, or a recent heart attack or stroke should not use PDE5 inhibitors until cleared by a doctor [2][4].

At a glance

What your prescriber will check before approving tadalafil and lisdexamfetamine together

When you request tadalafil through Cured Pharmacy's online consultation, you will be asked to list all your current medicines, including lisdexamfetamine. The prescriber will review your medical history and check several key points before deciding whether tadalafil is safe for you [2][4].

First, they will confirm that you do not have any absolute contraindications to PDE5 inhibitors, such as taking nitrates (GTN spray, isosorbide mononitrate), nicorandil, riociguat, or recreational drugs called poppers (alkyl nitrites) [3][4]. Combining tadalafil with any of these can cause a dangerous drop in blood pressure and is never safe. You must also not be taking another PDE5 inhibitor at the same time.

Second, the prescriber will assess your cardiovascular fitness. They will ask about any history of heart attack, stroke, angina, heart failure, abnormal heart rhythms, or very low blood pressure [2][4]. If you have been prescribed lisdexamfetamine, your ADHD specialist will already have checked your heart before starting the stimulant, but the ED prescriber needs to confirm that your condition remains stable and that sexual activity is not inadvisable for you.

Third, they will check your current blood pressure if known, and whether you take any other blood-pressure medicines (such as ACE inhibitors, calcium-channel blockers, or beta-blockers). These do not rule out tadalafil, but the prescriber may start you on a lower dose to minimise the risk of dizziness [4]. If you also take an alpha-blocker for prostate symptoms (such as tamsulosin or doxazosin), extra caution is needed because the combination with tadalafil can cause postural hypotension (a sudden drop in blood pressure when you stand up) [3][4].

Practical advice for taking tadalafil and lisdexamfetamine safely

If your prescriber approves tadalafil, follow the dosing instructions carefully. For on-demand use, take one 10 mg or 20 mg tablet at least 30 minutes before you plan to have sex; the effect can last up to 36 hours, so you should not take another dose within that window [4]. For daily use, take one 2.5 mg or 5 mg tablet at the same time each day, regardless of when you have sex. Tadalafil requires sexual stimulation to work—it will not cause an erection on its own [4].

Continue taking your lisdexamfetamine exactly as prescribed by your ADHD specialist. Do not stop or change the dose without their advice. Lisdexamfetamine is usually taken once in the morning; taking it later in the day can interfere with sleep [12]. There is no need to time your tadalafil dose around your lisdexamfetamine—just take each medicine as directed.

Monitor how you feel, especially when you first start the combination. If you experience dizziness, light-headedness, chest pain, palpitations (a racing or irregular heartbeat), or shortness of breath, stop sexual activity and seek medical advice promptly [2][4]. These symptoms may indicate that your blood pressure or heart rate is not stable. Avoid heavy alcohol, which can worsen erectile dysfunction and add to the blood-pressure-lowering effect of tadalafil [4].

Stay well hydrated and avoid overheating, as both lisdexamfetamine and sexual activity can raise your core temperature. If you develop an erection lasting more than four hours (priapism), go to A&E immediately, as this is a medical emergency that requires urgent treatment to prevent permanent damage [3][4].

When to contact your doctor

If you notice any new or worsening symptoms after starting tadalafil—such as chest discomfort during sex, unexplained breathlessness, fainting, or severe headaches—contact your GP or ADHD specialist the same day [2][4]. Your lisdexamfetamine dose or cardiovascular monitoring may need to be reviewed. Never take more tadalafil than prescribed in an attempt to improve the effect; higher doses increase the risk of side effects without necessarily improving erections [4].

Are there alternative ED treatments if tadalafil and lisdexamfetamine are not suitable together?

If your prescriber has concerns about your cardiovascular health, they may suggest starting with a lower dose of tadalafil (such as 10 mg on-demand or 2.5 mg daily) and reviewing how you tolerate it before increasing the dose [4]. Alternatively, they may recommend a different PDE5 inhibitor. Sildenafil (Viagra) has a shorter duration of action (about four to six hours) and may be preferred if you want more control over timing [3]. Vardenafil and avanafil are other options, though all PDE5 inhibitors carry similar cardiovascular considerations [5][6].

If PDE5 inhibitors are not suitable or not effective, other prescription treatments are available. Alprostadil is a medicine that can be applied as a cream (Vitaros) to the tip of the penis or injected directly into the penis (Caverject) [7]. These work by a different mechanism and do not rely on sexual stimulation, but they require careful instruction and are usually reserved for men who cannot use tablets [7].

Non-drug options include vacuum erection devices (pumps) and, in some cases, penile implants fitted by a urologist [2]. Psychological support, such as cognitive behavioural therapy or sex therapy, can be very helpful if anxiety or relationship issues are contributing to erectile dysfunction [2]. Your GP can refer you to specialist services if needed.

Lifestyle changes also play an important role. Regular exercise, a healthy weight, stopping smoking, and reducing alcohol can all improve erectile function and cardiovascular health, which is particularly important if you are taking lisdexamfetamine [1][2]. Discuss any concerns with your ADHD specialist or GP, who can coordinate your care and ensure all your treatments work safely together.

How to order tadalafil from Cured Pharmacy if you take lisdexamfetamine

Cured Pharmacy is a GPhC-registered online pharmacy (GPhC 9012511) offering a convenient, confidential service for erectile dysfunction treatment. To request tadalafil, complete a short online consultation form that asks about your medical history, current medicines (including lisdexamfetamine), and any heart or blood-pressure conditions [2][4]. A UK-registered prescriber will review your answers and decide whether tadalafil is safe and appropriate for you.

If approved, your medicine is dispensed by our pharmacy team and delivered discreetly to your home. We stock a range of tadalafil options, including generic Tadalafil at £7.95 for four tablets (£6.36 with first-order code Ednew), Tadalafil 20 mg (Teva) at £9.99 (£7.99 with code Ednew), Avarante 10 mg at £11.49 (£9.19 with code Ednew), and branded Cialis at £12.00 (£9.60 with code Ednew). All prices include the prescriber review and delivery.

If the prescriber has any concerns about the combination of tadalafil and lisdexamfetamine in your case, they may ask for more information, suggest a lower starting dose, or recommend that you speak to your GP or ADHD specialist before proceeding [2][4]. This is a safety measure to protect your health, and we encourage you to follow their advice. You can update your consultation answers at any time if your medical situation changes.

Remember, erectile dysfunction can be an early warning sign of heart disease or diabetes, so if this is a new problem for you, it is important to see your GP for a full check-up [1][2]. Treating ED is not just about restoring sexual function—it is also an opportunity to improve your overall health and reduce your risk of serious cardiovascular events in the future.

Why choose Cured Pharmacy?

Cured Pharmacy combines clinical expertise with convenience. Every prescription is reviewed by a UK-registered prescriber, and our pharmacists are available to answer questions about your treatment. We offer clear, honest pricing with no hidden fees, fast delivery, and the reassurance that your care meets the same standards as your local high-street pharmacy. If you have any concerns about taking tadalafil and lisdexamfetamine together, our team is here to help you make an informed decision.

When to get urgent help

• Chest pain or discomfort during or after sex—call 999 or go to A&E immediately
• Erection lasting more than four hours (priapism)—go to A&E for urgent treatment
• Sudden loss of vision or hearing—stop tadalafil and seek emergency medical help
• Severe dizziness, fainting, or palpitations—contact your GP urgently or call 111
• Shortness of breath or swelling of the face, lips, or throat—call 999, as this may be an allergic reaction

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

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