Tadalafil and Fludrocortisone: Can They Be Taken Together?

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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 phosphodiesterase type 5 (PDE5) inhibitors, which also includes sildenafil (Viagra), vardenafil (Levitra), and avanafil (Spedra) [3][4]. Tadalafil works by relaxing the blood vessels in the penis, allowing more blood to flow in when you are sexually aroused. It does not cause an erection on its own—sexual stimulation is still needed.

Tadalafil is available in two forms: on-demand tablets (usually 10 mg or 20 mg, taken at least 30 minutes before sex, with effects lasting up to 36 hours) and daily low-dose tablets (2.5 mg or 5 mg, taken once a day) [4]. The longer duration of action is why tadalafil is sometimes called the 'weekend pill'. At Cured Pharmacy, tadalafil is available on prescription after an online consultation with a UK-registered prescriber, who will check your medical history and current medicines to ensure it is safe and suitable for you.

What Is Fludrocortisone and Why Is It Prescribed?

Fludrocortisone is a corticosteroid medicine that acts on the kidneys to help the body retain sodium (salt) and water, which increases blood volume and raises blood pressure. It is most commonly prescribed for conditions such as Addison's disease (adrenal insufficiency), postural hypotension (low blood pressure when standing up), and certain salt-losing syndromes. By helping to maintain stable blood pressure, fludrocortisone can reduce symptoms such as dizziness, fainting, and fatigue.

Because fludrocortisone is designed to increase blood pressure, your doctor will monitor you regularly to ensure your blood pressure stays within a safe range. If you are taking fludrocortisone and are considering treatment for erectile dysfunction, it is essential that your prescriber knows about this medicine so they can assess whether a PDE5 inhibitor like tadalafil is appropriate and, if so, at what dose.

How Fludrocortisone Affects Your Body

Fludrocortisone mimics the action of aldosterone, a natural hormone produced by the adrenal glands. It works by increasing the reabsorption of sodium in the kidneys, which in turn causes the body to hold on to more water. This extra fluid increases the volume of blood circulating in your body, which raises your blood pressure. For people with conditions that cause dangerously low blood pressure, this effect is beneficial and can significantly improve quality of life. However, it also means that any additional medicine that affects blood pressure—whether raising or lowering it—needs to be carefully considered.

When to get urgent help

• An erection lasting more than 4 hours (priapism)—go to A&E immediately
• Sudden loss of vision or hearing—seek urgent medical help
• Chest pain during or after sex—call 999; do not take nitrates if you have used tadalafil in the past 48 hours
• Severe dizziness, fainting, or a very fast or slow heartbeat—contact your GP urgently or call 111
• Signs of an 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.

Can You Take Tadalafil and Fludrocortisone Together?

There is no well-documented major direct drug interaction between tadalafil and fludrocortisone, and many men take both medicines together without problems. However, because tadalafil can cause a modest drop in blood pressure (as part of its mechanism of relaxing blood vessels) and fludrocortisone is used to raise blood pressure, your prescriber will want to ensure that the combination does not cause unwanted effects such as dizziness, light-headedness, or fluctuations in blood pressure [3][4].

During your online consultation at Cured Pharmacy, the prescriber will review your full medical history, including why you are taking fludrocortisone, your current blood pressure readings, and any other medicines you are on. If tadalafil is considered safe for you, the prescriber may start you on a lower dose and advise you to monitor how you feel, especially when standing up quickly. It is important never to stop or change the dose of fludrocortisone without speaking to the doctor who prescribed it, as this could affect your underlying condition.

How Tadalafil and Fludrocortisone May Affect Blood Pressure

Tadalafil works by inhibiting an enzyme called PDE5, which leads to relaxation of smooth muscle in blood vessels. This effect is most pronounced in the penis, but it can also cause a small, temporary drop in blood pressure throughout the body [4]. For most men, this drop is mild and does not cause symptoms. However, if you are taking fludrocortisone to manage low blood pressure or postural hypotension, your prescriber will want to be cautious to avoid any risk of dizziness or fainting, particularly when you first start tadalafil or if the dose is increased.

Fludrocortisone, on the other hand, raises blood pressure by increasing fluid retention. In theory, the blood-pressure-lowering effect of tadalafil and the blood-pressure-raising effect of fludrocortisone could partially counteract each other. In practice, this is usually not a problem, but it does mean that your prescriber will take extra care to ensure your blood pressure remains stable and that you do not experience symptoms such as dizziness, headache, or feeling faint. If you notice any of these symptoms after starting tadalafil, contact your GP or the prescribing service promptly.

What Your Prescriber Will Check

Before prescribing tadalafil, the clinician will ask about your current blood pressure, any history of heart or blood vessel problems, and all the medicines you are taking, including fludrocortisone. They may also ask whether you experience dizziness or fainting, especially when standing up. If you have recently had your blood pressure checked by your GP, it can be helpful to have those readings to hand. The prescriber may recommend starting on a lower dose of tadalafil (for example, 10 mg rather than 20 mg) and reviewing how you get on before considering any increase. This cautious approach helps to minimise the risk of side effects while still providing effective treatment for erectile dysfunction.

At a glance

Practical Advice for Taking Tadalafil and Fludrocortisone Safely

If you are prescribed tadalafil while taking fludrocortisone, there are a few practical steps you can take to use both medicines safely. First, always take each medicine exactly as prescribed—do not adjust the dose or timing without speaking to your doctor or pharmacist. Take tadalafil at least 30 minutes before sexual activity (or daily if you are on the low-dose regimen), and continue taking fludrocortisone as directed by your GP. If you are on the on-demand form of tadalafil, avoid taking it more than once in 24 hours.

Be mindful of how you feel, especially in the first few days after starting tadalafil. Stand up slowly from sitting or lying down to reduce the risk of dizziness. Avoid drinking large amounts of alcohol, as this can add to the blood-pressure-lowering effect and make erectile dysfunction worse [1]. If you experience persistent dizziness, light-headedness, or any new symptoms, contact your GP or the prescribing service. Keep all your regular appointments for blood pressure monitoring, and let your doctor know if you start or stop any new medicines, including over-the-counter products or herbal supplements.

When Tadalafil Should Not Be Used

While tadalafil and fludrocortisone can often be taken together, there are some situations where tadalafil must not be used at all. Do not take tadalafil if you are using nitrate medicines (such as GTN spray, isosorbide mononitrate, or isosorbide dinitrate), nicorandil, riociguat, or recreational drugs known as 'poppers' (amyl or alkyl nitrites). The combination can cause a dangerous, potentially life-threatening drop in blood pressure [3][4]. Never take tadalafil alongside another PDE5 inhibitor (such as sildenafil, vardenafil, or avanafil).

Tadalafil is also 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 sudden vision loss (non-arteritic anterior ischaemic optic neuropathy, or NAION) [4]. If you have any of these conditions, your prescriber will discuss alternative treatments for erectile dysfunction. Always be honest and thorough when completing your online consultation, as this information is essential for your safety.

Other Medicines That May Interact with Tadalafil

In addition to the absolute contraindications listed above, tadalafil can interact with several other types of medicine. Alpha-blockers (such as doxazosin, tamsulosin, or alfuzosin, often used for prostate problems) can add to the blood-pressure-lowering effect of tadalafil, so you should be stable on the alpha-blocker before starting a PDE5 inhibitor, and the lowest dose of tadalafil should be used initially [3][4]. Potent CYP3A4 inhibitors (such as ritonavir, ketoconazole, itraconazole, or clarithromycin) can raise tadalafil levels in the blood, requiring dose adjustments. Conversely, CYP3A4 inducers (such as rifampicin, carbamazepine, or St John's wort) can reduce tadalafil's effectiveness. Your prescriber will review all your current medicines during the consultation to identify any potential interactions.

In summary

• No major direct interaction is commonly reported between tadalafil and fludrocortisone.
• Both medicines affect blood pressure in opposite ways, so your prescriber will review your history carefully.
• You may be started on a lower dose of tadalafil and monitored for dizziness or light-headedness.
• Never take tadalafil with nitrates, nicorandil, riociguat, poppers, or another PDE5 inhibitor.
• Always declare all your current medicines during your online consultation for safe prescribing.

Frequently Asked Questions