Tadalafil Overdose Symptoms: What You Need to Know

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At a glance

What are the symptoms of tadalafil overdose?

The symptoms of tadalafil overdose are usually an intensification of the medicine's known side effects [4]. Common overdose symptoms include severe headache, marked dizziness or light-headedness, fainting or near-fainting episodes, and visual disturbances such as blurred vision or changes in colour perception. Nausea, vomiting, and flushing may also become more pronounced.

One of the most serious tadalafil overdose symptoms is a dangerous drop in blood pressure, which can cause you to feel extremely dizzy, weak, or to lose consciousness [4]. This risk is particularly high if tadalafil is combined with nitrates, nicorandil, or recreational drugs known as 'poppers', which is why these combinations are strictly contraindicated.

Priapism—a painful erection lasting more than four hours—is a medical emergency that can occur with overdose [4]. This condition requires immediate treatment to prevent permanent damage to the penis. If you experience an erection lasting longer than four hours, go to A&E immediately, even if it is not painful.

Other potential overdose symptoms include back pain, muscle aches, nasal congestion, and indigestion, all occurring with greater severity than usual [4]. Rarely, sudden loss of vision in one or both eyes or sudden decrease or loss of hearing may occur, and these require urgent medical assessment.

What is the maximum safe dose of tadalafil?

The maximum recommended dose of tadalafil for erectile dysfunction depends on whether you are using it on-demand or daily [4]. For on-demand use, the maximum single dose is 20mg, taken at least 30 minutes before sexual activity. You should not take more than one dose in a 24-hour period, regardless of the strength.

For daily use, tadalafil is prescribed at a lower dose of 2.5mg or 5mg taken once every day at approximately the same time [4]. The maximum daily dose for continuous use is 5mg. This regimen allows for spontaneity, as the medicine builds up in your system and you do not need to time doses around sexual activity.

Taking more than the maximum recommended dose does not improve effectiveness and significantly increases the risk of side effects and overdose symptoms [4]. The prescriber will determine the appropriate starting dose based on your medical history, other medicines you take, and how well you respond to treatment.

Certain factors require dose adjustments. If you have moderate liver or kidney problems, or if you take medicines that interact with tadalafil (such as some HIV medicines or antifungal drugs), your maximum dose may be lower [4]. Your prescriber will review all your current medicines during the consultation to ensure safe dosing. At Cured Pharmacy, every prescription is reviewed by a UK-registered prescriber before dispensing.

Dose adjustments for specific situations

If you take alpha-blockers for prostate problems or high blood pressure (such as doxazosin or tamsulosin), you should start on the lowest dose of tadalafil and your prescriber must ensure you are stable on the alpha-blocker first [4]. The combination can cause a significant drop in blood pressure, so careful monitoring is essential.

Potent CYP3A4 inhibitors—including ritonavir, cobicistat (found in some HIV medicines and Paxlovid), ketoconazole, itraconazole, and clarithromycin—can raise tadalafil levels in your blood [4]. If you take any of these, your maximum tadalafil dose will be reduced. For on-demand use, the maximum is usually 10mg in 72 hours; daily tadalafil may not be recommended. Never adjust your dose yourself; your prescriber will determine the safe dose based on your complete medication list.

What should you do if you take too much tadalafil?

If you have taken more tadalafil than prescribed, contact NHS 111 for advice immediately, or go to your nearest A&E department if you develop severe symptoms such as fainting, chest pain, or an erection lasting more than four hours [4]. Take the medicine packet or patient information leaflet with you so healthcare professionals know exactly what you have taken and when.

Do not try to 'counteract' the overdose by taking other medicines or substances. In particular, never use nitrates (such as GTN spray), nicorandil, or recreational drugs like poppers, as these can cause a life-threatening drop in blood pressure when combined with tadalafil [4]. Avoid alcohol, as it can worsen low blood pressure and dizziness.

While waiting for medical help, lie down to reduce the risk of fainting from low blood pressure. If you feel dizzy or light-headed, do not stand up quickly. Drink water if you are able to swallow safely, but do not eat or drink anything if you are feeling very unwell or have been told not to by a healthcare professional.

Treatment for tadalafil overdose is supportive, meaning healthcare professionals will monitor your vital signs (blood pressure, heart rate) and treat symptoms as they arise [4]. There is no specific antidote for tadalafil. Because tadalafil has a long half-life and can remain active in your system for up to 36 hours, you may need monitoring for an extended period. Always be honest with healthcare professionals about how much you took and when, as this information is crucial for your safe treatment.

What you need to know

• Tadalafil overdose symptoms include severe headache, dizziness, fainting, prolonged erection, and dangerously low blood pressure
• Maximum dose is 20mg for on-demand use or 5mg daily; never take more than one dose in 24 hours
• Seek urgent help for erection lasting over 4 hours, chest pain, fainting, or sudden vision or hearing loss
• Never combine tadalafil with nitrates, nicorandil, poppers, or another PDE5 inhibitor
• Contact NHS 111 or A&E immediately if you have taken more tadalafil than prescribed

Why do people take more tadalafil than prescribed?

Some men mistakenly believe that taking a higher dose will produce better or faster results, but this is not how tadalafil works [4]. The medicine requires sexual stimulation to be effective, and taking more than prescribed does not enhance erections—it only increases the risk of side effects and overdose symptoms.

Others may take an additional dose if the first one 'did not work', not realising that tadalafil can take up to two hours to reach full effect and that factors like a heavy meal, excessive alcohol, or anxiety can interfere with its effectiveness [4]. It is important to give the medicine adequate time to work and to address any lifestyle factors that may be affecting your response.

Occasionally, accidental overdose occurs when someone forgets they have already taken a dose and takes another, particularly with daily tadalafil where the routine may be disrupted [4]. Using a pill organiser or setting a daily reminder can help prevent this. If you do accidentally take a double dose of daily tadalafil (for example, 5mg twice in one day), skip the next day's dose and resume your normal schedule the following day, but contact NHS 111 or your prescriber for advice.

Some men obtain tadalafil from unregulated sources without proper medical assessment, which can lead to inappropriate dosing and dangerous interactions with other medicines [4]. Always obtain tadalafil through a legitimate pharmacy after a consultation with a qualified prescriber. At Cured Pharmacy, a UK-registered prescriber reviews every request to ensure the medicine and dose are safe and appropriate for you.

The importance of proper medical assessment

Erectile dysfunction can be an early warning sign of underlying health conditions such as cardiovascular disease, diabetes, or hormonal imbalances [1][2]. This is why it is important to see your GP for new or worsening ED, even if you also use an online service for treatment. Your GP can arrange tests to identify any underlying causes that need specific treatment.

A proper medical assessment also identifies contraindications and interactions that make tadalafil unsafe for some men [4]. For example, tadalafil is not suitable if you have recently had a heart attack or stroke, have unstable angina, severe heart failure, very low blood pressure, or a history of non-arteritic anterior ischaemic optic neuropathy (sudden vision loss). Your prescriber needs accurate information about your health and all medicines you take to prescribe safely.

How can you use tadalafil safely to avoid overdose symptoms?

Always take tadalafil exactly as prescribed by your doctor or prescriber [4]. Do not take more than one on-demand dose in 24 hours, and do not exceed the maximum dose recommended for your individual circumstances. If you feel the prescribed dose is not effective, speak to your prescriber about adjusting your treatment rather than increasing the dose yourself.

Keep a clear record of when you take tadalafil, especially if you use the on-demand formulation. Because tadalafil can remain active in your system for up to 36 hours, you must wait at least 24 hours before taking another dose [4]. Setting a reminder on your phone can help ensure you do not accidentally take doses too close together.

Store tadalafil safely out of reach of children and other household members. Keep the tablets in their original packaging with the patient information leaflet, so you always have dosing instructions to hand. Do not share your tadalafil with others, even if they have similar symptoms, as the medicine may not be safe for them.

Avoid drinking excessive alcohol when taking tadalafil, as alcohol can increase the risk of side effects such as dizziness, headache, and low blood pressure [4]. Grapefruit juice can also raise tadalafil levels in your blood, so it is best avoided. If you develop any new symptoms or side effects, contact your prescriber or pharmacist for advice rather than stopping the medicine abruptly or changing your dose.

When to get urgent help

• Erection lasting more than 4 hours (priapism), even if not painful—go to A&E immediately
• Chest pain during or after sex, especially with shortness of breath or sweating—call 999
• Sudden loss of vision in one or both eyes—stop tadalafil and seek urgent medical help
• Severe dizziness, fainting, or feeling faint—contact NHS 111 or go to A&E
• Sudden decrease or loss of hearing, possibly with ringing or dizziness—seek urgent medical assessment

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

When should you seek urgent help for tadalafil overdose symptoms?

Seek immediate medical help by calling 999 or going to A&E if you experience an erection lasting more than four hours (priapism), even if it is not painful [4]. This is a medical emergency that requires urgent treatment to prevent permanent damage to the erectile tissue. Do not delay seeking help out of embarrassment—healthcare professionals are experienced in treating this condition discreetly and professionally.

Call 999 or go to A&E immediately if you develop chest pain during or after sexual activity, especially if it spreads to your arms, neck, or jaw, or is accompanied by shortness of breath, nausea, or sweating [4]. These could be signs of a heart problem that needs urgent assessment. Do not take nitrate medicines (such as GTN spray) if you have taken tadalafil within the past 48 hours, as the combination can cause a dangerous drop in blood pressure.

Sudden loss of vision in one or both eyes, or sudden decrease or loss of hearing (sometimes with ringing in the ears or dizziness), requires urgent medical attention [4]. Stop taking tadalafil and contact a doctor immediately if you experience these symptoms. While rare, these events have been reported with PDE5 inhibitors and need prompt assessment.

Severe dizziness, fainting, or feeling like you are about to faint are signs of very low blood pressure and require urgent medical assessment, especially if you have also taken other medicines that lower blood pressure [4]. Contact NHS 111 for advice if you develop severe side effects that are not emergencies but are concerning, such as severe headache, prolonged nausea or vomiting, or visual disturbances. Always mention that you have taken tadalafil and how much.

Interactions that increase overdose risk

Never take tadalafil if you use nitrates (GTN spray, isosorbide mononitrate or dinitrate), nicorandil, riociguat, or recreational drugs known as 'poppers' (amyl or alkyl nitrites) [4]. The combination can cause a severe and potentially life-threatening drop in blood pressure. This applies even if you only use nitrates occasionally, such as GTN spray for angina. If you develop chest pain while taking tadalafil, do not use your GTN spray—call 999 immediately.

Some medicines can significantly raise tadalafil levels in your blood, increasing the risk of overdose symptoms even at normal doses [4]. These include potent CYP3A4 inhibitors such as ritonavir, cobicistat, ketoconazole, itraconazole, and clarithromycin. Your prescriber must know about all medicines you take, including those prescribed by different doctors, over-the-counter medicines, and herbal supplements. Never start a new medicine without checking with your prescriber or pharmacist that it is safe to take with tadalafil.