Tadalafil and Alendronic Acid: Can You Take Them Together?

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Tadalafil and Alendronic Acid: Understanding the Interaction

Published: 18 October 2026

Many men taking alendronic acid for osteoporosis or bone health wonder whether tadalafil and alendronic acid can be taken together safely. The good news is that no major interaction between these two medicines is commonly reported, and they are often prescribed together. However, every medication combination requires careful assessment by a prescriber, who will review your full medical history and current medicines during a consultation.

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 increased blood flow when you are sexually aroused [4]. Tadalafil does not cause an erection on its own—sexual stimulation is still needed.

Tadalafil is available in two forms: on-demand tablets (usually 10mg or 20mg) taken at least 30 minutes before sexual activity, with effects lasting up to 36 hours, and daily low-dose tablets (2.5mg or 5mg) taken once a day at the same time [4]. The longer duration of action is why tadalafil is sometimes called 'the weekend pill'. At Cured Pharmacy, tadalafil is available after an online consultation reviewed by a UK prescriber, with generic Tadalafil priced at £7.95 (or £6.36 for first orders with code Ednew).

What is Alendronic Acid and Why is It Prescribed?

Alendronic acid (also called alendronate) is a bisphosphonate medicine used to treat and prevent osteoporosis, a condition where bones become weak and fragile. It works by slowing down the cells that break down bone, helping to maintain bone density and reduce the risk of fractures. Alendronic acid is commonly prescribed to postmenopausal women and older men, as well as people taking long-term corticosteroids.

The medicine is usually taken once a week as a 70mg tablet, always on an empty stomach first thing in the morning with a full glass of plain water. You must then stay upright (sitting or standing) for at least 30 minutes and avoid eating, drinking anything other than water, or taking other medicines during this time. This is because alendronic acid can irritate the oesophagus (food pipe) if it does not reach the stomach quickly.

Common Uses of Alendronic Acid

Alendronic acid is prescribed for osteoporosis in postmenopausal women, osteoporosis in men, steroid-induced osteoporosis (when long-term corticosteroid use weakens bones), and Paget's disease of bone. It is an effective treatment that has been shown to reduce the risk of spine and hip fractures when taken correctly over time.

Do Tadalafil and Alendronic Acid Interact?

There is no significant pharmacological interaction between tadalafil and alendronic acid. These medicines work on completely different systems in the body: tadalafil affects blood flow to the penis by inhibiting the PDE5 enzyme, while alendronic acid works on bone cells to slow bone breakdown. They are not known to interfere with each other's effectiveness or increase the risk of side effects when taken together.

However, it is important to understand that 'no major interaction' does not mean you can simply combine medicines without professional advice. Every person's medical situation is unique, and a prescriber will always review your complete medication list, underlying health conditions, and individual risk factors during a consultation. This is why prescription medicines like tadalafil are only supplied after an online assessment by a UK-registered prescriber.

If you are taking alendronic acid and considering tadalafil for erectile dysfunction, you should declare all your current medicines during the consultation. The prescriber will check for any less common interactions, ensure the timing of doses is appropriate, and confirm that tadalafil is suitable for you based on your overall health [2].

What Your Prescriber Checks Before Approving Tadalafil

When you request tadalafil, the prescriber conducts a thorough assessment to ensure it is safe and appropriate for you. They will ask about your cardiovascular health, as erectile dysfunction can be an early warning sign of heart disease or diabetes [1]. If you have not seen a GP about your ED before, you may be advised to do so for a full health check.

The prescriber will specifically check for contraindications—conditions or medicines that mean tadalafil must not be used. These include nitrate medicines (such as GTN spray, isosorbide mononitrate or dinitrate), nicorandil, riociguat, and recreational drugs called 'poppers' (amyl or alkyl nitrites). Taking tadalafil with any of these can cause a dangerous drop in blood pressure [4]. You must never take tadalafil if you use any of these substances.

Other important checks include whether you take alpha-blockers for prostate problems or high blood pressure (such as doxazosin or tamsulosin), as these can also lower blood pressure when combined with tadalafil. If you are stable on an alpha-blocker, tadalafil can usually be prescribed, but you will start on the lowest dose [4]. The prescriber will also review medicines that affect how your body processes tadalafil, such as certain antifungals, antibiotics, or HIV medicines.

Declaring Your Full Medication List

Always provide a complete and accurate list of everything you take, including prescription medicines, over-the-counter products, herbal remedies, and supplements. Even if you think a medicine is unrelated to ED, it may still be relevant to the prescriber's safety assessment. For example, St John's wort (a herbal remedy for low mood) can reduce the effectiveness of tadalafil.

Practical Advice for Taking Tadalafil and Alendronic Acid Together

If you have been prescribed both medicines, the key to success is taking each one correctly according to its instructions. Alendronic acid must be taken first thing in the morning on an empty stomach with a full glass of plain water, and you must remain upright for at least 30 minutes without eating or drinking anything else. This timing is crucial to prevent irritation of the oesophagus and ensure the medicine is absorbed properly.

Tadalafil, on the other hand, can be taken with or without food (though a very heavy, high-fat meal may delay its effect slightly). If you are using on-demand tadalafil, take it at least 30 minutes before sexual activity—this is usually later in the day, well after your morning dose of alendronic acid. If you are taking daily low-dose tadalafil, choose a time that works for you, but make sure it is at least 30 minutes after your alendronic acid dose and morning routine.

There is no need to separate the medicines by many hours, as they do not interact. The main consideration is simply following the specific instructions for alendronic acid. If you experience any unusual symptoms after starting tadalafil, such as persistent indigestion, difficulty swallowing, or new chest pain, contact your GP or pharmacist for advice.

When to Seek Medical Advice About Tadalafil and Alendronic Acid

While tadalafil and alendronic acid can generally be taken together, certain situations require prompt medical attention. If you develop severe or persistent heartburn, difficulty swallowing, or pain when swallowing after taking alendronic acid, stop the medicine and see your GP, as these can be signs of oesophageal irritation. Similarly, if you experience new or worsening bone, joint, or muscle pain while taking alendronic acid, discuss this with your doctor.

For tadalafil, seek urgent help if you have an erection lasting more than four hours (priapism), sudden loss of vision in one or both eyes, or sudden decrease or loss of hearing. These are rare but serious side effects that need immediate medical attention [4]. If you experience chest pain during or after sexual activity, stop and seek urgent medical help—do not take more tadalafil or use a GTN spray, as the combination is dangerous.

If you are unsure whether a new symptom is related to either medicine, or if you need to start a new treatment while taking tadalafil and alendronic acid, speak to your GP or pharmacist. Never stop a prescribed medicine like alendronic acid without professional advice, as this could affect your bone health.

Reporting Side Effects

If you experience side effects from any medicine, you can report them via the Yellow Card Scheme at yellowcard.mhra.gov.uk or by searching for 'Yellow Card' in the Google Play or Apple App Store. Reporting helps improve the safety of medicines for everyone.

Scientific References

1. NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 18 October 2026]
2. National Institute for Health and Care Excellence. (n.d.). Erectile dysfunction. Clinical Knowledge Summaries. https://cks.nice.org.uk/topics/erectile-dysfunction/ [accessed 18 October 2026]
3. Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 18 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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