Tadalafil and Lithium: Can They Be Taken Together?
Learn about the interaction, safety checks, and practical advice from UK pharmacists.
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Tadalafil and Lithium: Understanding the Interaction
Published: 22 October 2026
Many men taking lithium for bipolar disorder or other mood conditions wonder whether tadalafil and lithium can be taken together safely. The good news is that no major direct interaction between tadalafil (Cialis) and lithium is commonly reported in clinical practice, and the two medicines are often prescribed together. However, every person's situation is different, and your prescriber will carefully review your full medical history, current medicines, and overall health before confirming that tadalafil is suitable for you.
Always declare all medicines
Even if you think a medicine is unrelated, always list every tablet, capsule, spray, patch, or supplement you use during your consultation. This ensures your prescriber can check for interactions and confirm tadalafil is safe for you.
What is tadalafil and lithium used for?
Tadalafil is a phosphodiesterase type 5 (PDE5) inhibitor licensed in the UK to treat erectile dysfunction (ED) in men [4]. It works by relaxing blood vessels in the penis, allowing increased blood flow when you are sexually aroused. Tadalafil is available as an on-demand treatment (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 tablet (2.5 mg or 5 mg) [4]. It is sold under the brand name Cialis and as generic tadalafil. All forms require sexual stimulation to work and will not cause an erection on their own.
Lithium is a mood stabiliser prescribed for bipolar disorder, severe depression, and sometimes to prevent recurrent mood episodes [12]. It works by affecting the balance of certain chemicals in the brain. Lithium requires regular blood tests to monitor levels, as the therapeutic window is narrow and side effects can occur if levels become too high. Common side effects include thirst, increased urination, tremor, and weight gain. Because lithium affects fluid balance and kidney function, your doctor will monitor you closely while you are taking it.
How do tadalafil and lithium interact in the body?
There is no well-documented pharmacological interaction between tadalafil and lithium. Tadalafil is metabolised mainly by the liver enzyme CYP3A4, while lithium is not broken down by the liver—it is excreted unchanged by the kidneys [4][12]. This means the two medicines do not compete for the same metabolic pathways, and one does not typically alter the blood levels of the other.
However, both medicines can affect blood pressure. Tadalafil causes mild vasodilation (widening of blood vessels), which can lower blood pressure slightly [4]. Lithium itself does not usually lower blood pressure, but dehydration or changes in fluid balance—common with lithium—can indirectly affect cardiovascular stability. If you are also taking other medicines for high blood pressure, heart conditions, or diuretics, the combined effect on blood pressure needs careful consideration. Your prescriber will review all your current medicines during the consultation to ensure the combination is safe for you.
Why your prescriber checks your full medication list
Even though tadalafil and lithium do not directly interact, your prescriber must review every medicine you take, including over-the-counter products and supplements. This is because ED treatments can interact seriously with certain other medicines—particularly nitrates (GTN spray, isosorbide mononitrate), nicorandil, riociguat, and amyl nitrites (poppers)—which must never be taken with tadalafil [4]. Alpha-blockers (such as tamsulosin or doxazosin) and potent CYP3A4 inhibitors (like ritonavir or ketoconazole) also require dose adjustments or special precautions. Your prescriber will also check that your heart and blood pressure are healthy enough for sexual activity, as this is important for anyone considering ED treatment [2].
What does your prescriber check before prescribing tadalafil with lithium?
During your online consultation at Cured Pharmacy, the prescriber will ask about your current medicines, including lithium, the dose you take, and how long you have been on it. They will also ask about your general health, cardiovascular history, blood pressure, kidney function, and any other conditions you have. Because lithium requires regular monitoring, your prescriber may want to know when you last had blood tests and whether your lithium levels are stable.
The prescriber will also check for any contraindications to tadalafil, such as recent heart attack or stroke, unstable angina, severe heart failure, very low blood pressure, or use of nitrates or nicorandil [4]. They will ask about other medicines that might interact, including alpha-blockers, antifungals, HIV medicines, and other blood-pressure treatments. If you are taking multiple medicines or have complex health needs, the prescriber may request further information from your GP or suggest starting on a lower dose of tadalafil to minimise any risk of side effects.
It is essential to be completely honest and thorough when completing your consultation. Do not leave out any medicines, supplements, or health conditions, even if you think they are unrelated. This ensures the prescriber can make a safe, informed decision tailored to your individual circumstances.
What you need to know
- No major direct interaction between tadalafil and lithium is commonly reported.
- Your prescriber reviews all medicines and health conditions before prescribing tadalafil.
- Continue lithium and regular monitoring as prescribed; stay well hydrated.
- Never take tadalafil with nitrates, nicorandil, riociguat, or poppers.
- Seek urgent help for erections lasting over 4 hours or sudden vision or hearing loss.
Practical advice for taking tadalafil and lithium together
If your prescriber confirms that tadalafil is suitable for you, take it exactly as directed. For on-demand tadalafil (10 mg or 20 mg), take one tablet at least 30 minutes before you plan to have sex; the effect can last up to 36 hours, so you do not need to rush [4]. For daily tadalafil (2.5 mg or 5 mg), take one tablet at the same time each day, with or without food. Do not take more than the prescribed dose, and never take tadalafil more than once in 24 hours.
Continue taking your lithium exactly as prescribed by your doctor. Do not stop or change your lithium dose without medical advice, as this can destabilise your mood. Stay well hydrated, especially if you are taking lithium, as dehydration can raise lithium levels and increase the risk of side effects. Avoid heavy alcohol, as it can worsen erectile dysfunction and add to the blood-pressure-lowering effect of tadalafil [1]. Grapefruit juice can raise tadalafil levels, so it is best avoided or limited.
If you experience dizziness, light-headedness, or fainting after taking tadalafil, sit or lie down and avoid driving or operating machinery. These symptoms may indicate low blood pressure and should be reported to your doctor. If you develop any new side effects or your lithium side effects change after starting tadalafil, contact your GP or pharmacist for advice.
What to do if you start a new medicine
If your doctor prescribes a new medicine while you are taking both lithium and tadalafil, always tell them you are using an ED treatment. Some medicines—particularly nitrates, alpha-blockers, or potent antifungals—can interact with tadalafil and may require a dose change or alternative treatment [4]. Similarly, if you buy any over-the-counter medicines, herbal remedies, or supplements, check with your pharmacist first. Never take recreational drugs, especially amyl nitrites (poppers), as the combination with tadalafil can cause a dangerous drop in blood pressure [4].
Are there any warning signs to watch for with tadalafil and lithium?
Most men taking tadalafil and lithium together tolerate the combination well, but it is important to be aware of potential warning signs. Common side effects of tadalafil include headache, flushing, indigestion, nasal congestion, and back pain [4]. These are usually mild and short-lived. If you experience persistent or severe side effects, contact your pharmacist or GP for advice.
Seek urgent medical help if you develop an erection lasting more than four hours (priapism), as this is a medical emergency that requires immediate treatment to prevent permanent damage [4]. Sudden loss of vision in one or both eyes, or sudden hearing loss or ringing in the ears, are rare but serious side effects—stop taking tadalafil and seek medical attention straight away [4]. If you experience chest pain during or after sex, stop and seek urgent help, as this may indicate a heart problem.
For lithium, watch for signs of lithium toxicity, which can include severe nausea, vomiting, diarrhoea, tremor, confusion, slurred speech, or muscle weakness. These symptoms require urgent medical attention and blood tests to check lithium levels. Dehydration, illness, or starting a new medicine can all affect lithium levels, so stay alert and contact your doctor if you feel unwell or notice any changes.
When to get urgent help
- Erection lasting more than 4 hours (priapism) – go to A&E immediately
- Sudden loss of vision in one or both eyes – stop tadalafil and seek urgent medical help
- Sudden hearing loss or ringing in the ears – stop tadalafil and contact a doctor urgently
- Chest pain during or after sex – stop activity and seek urgent medical attention
- Signs of lithium toxicity (severe nausea, confusion, tremor, slurred speech) – contact your doctor or go to A&E
Call 999 or go to A&E in an emergency, or contact NHS 111 for urgent advice.
Other ED treatments and alternatives if tadalafil is not suitable
If tadalafil is not suitable for you, or if you prefer a different option, there are several other licensed ED treatments available in the UK. Sildenafil (Viagra) is taken about one hour before sex and lasts for around four to six hours [3]. Vardenafil (Levitra) works in 25–60 minutes, and avanafil (Spedra) can work in as little as 15–30 minutes [5][6]. All of these are PDE5 inhibitors and have similar interactions and precautions to tadalafil, so the same checks apply if you are taking lithium or other medicines.
Non-tablet options include Viagra Connect (sildenafil 50 mg) and Cialis Together (tadalafil 10 mg), which are available from pharmacies after a consultation with a pharmacist, for men aged 18 and over [1]. Eroxon is a topical gel medical device that can be bought without a prescription. For men who cannot use PDE5 inhibitors, prescription-only treatments such as Vitaros (alprostadil cream) or Caverject (alprostadil injection) may be considered [7].
It is also important to address any underlying causes of erectile dysfunction. ED can be an early warning sign of heart disease, diabetes, or other health conditions, so if you have not already done so, see your GP for a full health check [1][2]. Lifestyle changes—such as losing weight, exercising regularly, stopping smoking, and reducing alcohol—can all improve erectile function and overall health [1]. Psychological factors, such as stress, anxiety, or relationship issues, can also contribute to ED, and talking therapies or counselling may help.
How Cured Pharmacy can help
Cured Pharmacy is a GPhC-registered online pharmacy (GPhC 9012511) offering discreet, convenient access to ED treatments after a consultation with a UK-registered prescriber. We stock a range of options, including generic and branded tadalafil, sildenafil, vardenafil, and avanafil, all at transparent prices. Your consultation is reviewed by a qualified prescriber who will check your medical history, current medicines (including lithium), and overall health to ensure the treatment is safe and suitable for you. If you have any questions or concerns, our pharmacist-led team is here to provide clear, evidence-based advice and support.
Scientific References
- NHS. (n.d.). Erectile dysfunction (impotence). NHS website. https://www.nhs.uk/conditions/erection-problems-erectile-dysfunction/ [accessed 22 October 2026]
- National Institute for Health and Care Excellence. (n.d.). Erectile dysfunction. Clinical Knowledge Summaries. https://cks.nice.org.uk/topics/erectile-dysfunction/ [accessed 22 October 2026]
- Joint Formulary Committee. (n.d.). Sildenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/sildenafil/ [accessed 22 October 2026]
- Joint Formulary Committee. (n.d.). Tadalafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/tadalafil/ [accessed 22 October 2026]
- Joint Formulary Committee. (n.d.). Vardenafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/vardenafil/ [accessed 22 October 2026]
- Joint Formulary Committee. (n.d.). Avanafil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/avanafil/ [accessed 22 October 2026]
- Joint Formulary Committee. (n.d.). Alprostadil. British National Formulary. NICE. https://bnf.nice.org.uk/drugs/alprostadil/ [accessed 22 October 2026]
- Electronic Medicines Compendium. (n.d.). Summaries of Product Characteristics and Patient Information Leaflets. https://www.medicines.org.uk/emc/ [accessed 22 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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Your Questions Answered
Can I take tadalafil if I am on lithium?
Yes, in most cases tadalafil and lithium can be taken together safely, as no major direct interaction is commonly reported. Your prescriber will review your full medical history and all current medicines during the consultation to confirm it is suitable for you.
Will tadalafil affect my lithium levels?
Tadalafil does not directly affect lithium levels, as the two medicines are processed differently in the body. However, always continue your regular lithium blood tests and monitoring as advised by your doctor.
Do I need to tell my psychiatrist I am taking tadalafil?
Yes, it is good practice to inform all your doctors about every medicine you take, including ED treatments. This ensures coordinated care and helps avoid any potential issues.
Can lithium cause erectile dysfunction?
Lithium itself is not commonly associated with causing erectile dysfunction, but mental health conditions, other medicines, and general health can all contribute to ED. Speak to your GP if you have concerns.
What should I do if I feel dizzy after taking tadalafil?
Sit or lie down until the dizziness passes, and avoid driving or operating machinery. Dizziness can indicate low blood pressure; if it persists or is severe, contact your doctor or pharmacist for advice.
Can I drink alcohol while taking tadalafil and lithium?
Heavy alcohol can worsen erectile dysfunction and add to the blood-pressure-lowering effect of tadalafil. Moderate alcohol is usually acceptable, but it is best to limit intake for optimal results and safety.
Are there any medicines I must not take with tadalafil?
Yes, never take tadalafil with nitrates (GTN spray, isosorbide), nicorandil, riociguat, or amyl nitrites (poppers), as this can cause a dangerous drop in blood pressure. Always declare all medicines during your consultation.
How quickly does tadalafil work if I am taking lithium?
Tadalafil works in the same way whether or not you take lithium. On-demand tablets (10 mg or 20 mg) work in about 30 minutes, and the effect can last up to 36 hours. Daily tablets (2.5 mg or 5 mg) build up over a few days.
Medically reviewed by
Tarun Kumar, Superintendent Pharmacist (GPhC 2233073)