Can You Take Tadalafil and Naltrexone Together?

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At a glance

What is tadalafil and how does it work?

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 the blood vessels in the penis, allowing more blood to flow in when you are sexually aroused [4]. Tadalafil is the active ingredient in branded Cialis and is also available as a lower-cost generic.

Tadalafil is available in two ways: on-demand tablets (10mg or 20mg) taken at least 30 minutes before sexual activity, with effects lasting up to 36 hours, or daily low-dose tablets (2.5mg or 5mg) taken every day [4]. Both options require sexual stimulation to work—tadalafil does not cause an erection by itself.

Common side effects include headache, indigestion, back pain, muscle aches, and flushing [4]. Tadalafil is not suitable for everyone, particularly men taking nitrates for chest pain, those with severe heart problems, or anyone for whom sexual activity is inadvisable. Your prescriber will check your medical history and current medicines before prescribing tadalafil.

What is naltrexone and why is it prescribed?

Naltrexone is a prescription medicine used to help people who are dependent on alcohol or opioids to stay abstinent after they have stopped drinking or using opioids. It works by blocking opioid receptors in the brain, which reduces cravings and the rewarding effects of alcohol or opioids.

Naltrexone is usually prescribed as part of a comprehensive treatment programme that includes counselling and support. It is taken as a tablet (usually 50mg once daily) or as a long-acting injection given once a month. Naltrexone does not treat withdrawal symptoms and should only be started after you have been opioid-free for at least 7–10 days.

Common side effects of naltrexone include nausea, headache, dizziness, tiredness, and trouble sleeping. It is important to tell any healthcare professional that you are taking naltrexone, especially if you need pain relief, because it blocks the effects of opioid painkillers. Naltrexone does not directly affect blood pressure or the blood vessels in the same way that tadalafil does.

Does naltrexone cause erectile dysfunction?

Erectile dysfunction is not a commonly reported side effect of naltrexone itself. However, alcohol dependence and opioid use can both contribute to ED, so some men may experience erection problems as part of their underlying condition rather than as a direct result of naltrexone. If you notice new or worsening ED while taking naltrexone, it is worth discussing with your GP, as treating the underlying cause (such as improving overall health, managing stress, or addressing cardiovascular risk factors) may help [1].

Is there an interaction between tadalafil and naltrexone?

No major interaction between tadalafil and naltrexone is commonly reported in clinical practice or in the British National Formulary [4]. The two medicines work through different mechanisms in the body: tadalafil affects blood flow by inhibiting an enzyme called PDE5, while naltrexone blocks opioid receptors in the brain. Because they do not share the same metabolic pathways or directly interfere with each other's actions, they are generally considered compatible.

However, this does not mean the combination is automatically safe for everyone. Your prescriber will always review your full medical history, current medicines, and any other health conditions during your consultation. For example, if you have liver problems, both medicines may need dose adjustments or closer monitoring, as naltrexone can affect liver function and tadalafil is partly processed by the liver.

It is also important to remember that alcohol can worsen erectile dysfunction and increase the risk of side effects such as dizziness or low blood pressure when taking tadalafil [4]. If you are taking naltrexone as part of treatment for alcohol dependence, reducing or stopping alcohol may actually improve your erectile function over time. Always be honest with your prescriber about your alcohol use and any other medicines or supplements you are taking.

What you need to know

• No major interaction between tadalafil and naltrexone is commonly reported in clinical practice.
• Your prescriber reviews all your medicines and medical history during the online consultation.
• Never take tadalafil with nitrates, nicorandil, riociguat, poppers, or another PDE5 inhibitor.
• Reducing alcohol can improve erectile function and reduce side effects from tadalafil.
• Seek urgent help for erections lasting over four hours or sudden vision or hearing loss.

What does your prescriber check before prescribing tadalafil and naltrexone together?

When you request tadalafil through an online consultation at Cured Pharmacy, a UK-registered prescriber will review your medical questionnaire carefully. They will check for any contraindications to tadalafil, such as use of nitrates (GTN spray, isosorbide mononitrate or dinitrate), nicorandil, riociguat, or recreational drugs known as 'poppers' (amyl or alkyl nitrites), all of which must never be taken with tadalafil because the combination can cause a dangerous drop in blood pressure [4].

Your prescriber will also ask about other medicines you are taking, including naltrexone, to ensure there are no interactions that could affect safety or effectiveness. They will review your cardiovascular health, blood pressure, liver and kidney function, and whether you have any conditions that make sexual activity inadvisable, such as recent heart attack or stroke, unstable angina, or severe heart failure [2][4].

If you are taking alpha-blockers (such as doxazosin or tamsulosin for prostate symptoms), your prescriber will ensure you are stable on that medicine and may start you on a lower dose of tadalafil to reduce the risk of dizziness or low blood pressure [4]. If you are taking potent CYP3A4 inhibitors (such as ritonavir, ketoconazole, or clarithromycin), your tadalafil dose may need to be reduced. Your prescriber will also check for any other medicines that could interact with tadalafil or affect your suitability for treatment.

What information should you provide in your consultation?

Be open and accurate when completing your online consultation. List all prescription medicines, over-the-counter medicines, herbal remedies (such as St John's wort), and recreational drugs you use. Mention any heart problems, high or low blood pressure, liver or kidney disease, diabetes, or previous allergic reactions. If you have ever experienced sudden vision or hearing loss, or an erection lasting more than four hours, tell your prescriber. This information helps ensure tadalafil is safe and appropriate for you.

Practical advice for taking tadalafil and naltrexone safely

If your prescriber approves the combination of tadalafil and naltrexone, take each medicine exactly as directed. Tadalafil on-demand tablets (10mg or 20mg) should be taken at least 30 minutes before sexual activity, and you should not take more than one dose in 24 hours [4]. Daily tadalafil (2.5mg or 5mg) should be taken at the same time each day, whether or not you plan to have sex. Naltrexone is usually taken once daily, and you should continue it as prescribed by your GP or specialist.

Avoid drinking large amounts of alcohol, as this can make erectile dysfunction worse, increase the risk of side effects such as dizziness, and may undermine your treatment for alcohol dependence [4]. Grapefruit juice can increase tadalafil levels in your blood, so it is best to avoid it. If you experience common side effects such as headache, indigestion, or back pain, these are usually mild and temporary; however, if they are severe or persistent, contact your prescriber or pharmacist for advice.

Do not take tadalafil if you are also using another PDE5 inhibitor (such as sildenafil or vardenafil) or any medicine containing nitrates, nicorandil, riociguat, or poppers, as this can cause a dangerous drop in blood pressure [4]. If you are prescribed a new medicine by your GP or another healthcare professional, always tell them you are taking tadalafil and naltrexone. Never stop or change your naltrexone without discussing it with the doctor who prescribed it, as this could affect your recovery.

When to get urgent help

• Erection lasting longer than four hours (priapism)—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
• Chest pain during or after sex—call 999 and tell them you have taken tadalafil (do not use nitrate sprays)
• Severe dizziness, fainting, or signs of allergic reaction (swelling of face, lips, throat, or difficulty breathing)

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

When to seek medical help and warning signs to watch for

Most men take tadalafil and naltrexone together without problems, but you should know the warning signs that require urgent medical attention. If you develop an erection that lasts longer than four hours (priapism), go to A&E immediately, as this can cause permanent damage to the penis [4]. 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 assessment—stop taking tadalafil and seek help straight away [4].

If you experience chest pain during or after sexual activity, do not use nitrate medicines (such as GTN spray) to relieve it, as the combination with tadalafil can be dangerous. Instead, call 999 or go to A&E and tell the medical team you have taken tadalafil [4]. Severe dizziness, fainting, or signs of an allergic reaction (such as swelling of the face, lips, or throat, or difficulty breathing) also require emergency help.

If you develop signs of liver problems while taking naltrexone (such as yellowing of the skin or eyes, dark urine, severe tiredness, or persistent nausea), contact your GP urgently. If you notice new or worsening erectile dysfunction, it is worth seeing your GP for a review, as ED can be an early sign of underlying health problems such as diabetes or cardiovascular disease [1][2]. Your GP can check for treatable causes and refer you to a specialist if needed.

Can you get tadalafil through Cured Pharmacy if you take naltrexone?

Yes, you can request tadalafil through Cured Pharmacy's online consultation service if you are taking naltrexone, provided the prescriber assesses the combination as safe and appropriate for you. During the consultation, you will be asked about all your current medicines, including naltrexone, and your medical history. A UK-registered prescriber will review your answers and, if suitable, approve your prescription. Tadalafil will then be dispensed by our GPhC-registered pharmacy and delivered discreetly to your door. If you have any questions, our pharmacist-led team is here to help.

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