Cialis (Tadalafil) — Patient Information (UK)

Cialis contains the active ingredient tadalafil. It is used to treat erectile dysfunction (ED) in men and, in some doses, to treat signs and symptoms of benign prostatic hyperplasia (BPH) (an enlarged prostate). This page explains how Cialis works, how to take it safely, what to expect, and what interactions and precautions to consider.

Always follow the advice of a healthcare professional. If you are unsure whether Cialis is suitable for you, seek medical guidance—especially if you have heart problems or take medicines for blood pressure or angina.

1. Basic product information

2. What Cialis is for (indications)

Cialis is used to treat:

• Erectile dysfunction (ED) — difficulty achieving or maintaining an erection sufficient for sexual activity.
• Benign prostatic hyperplasia (BPH) — symptoms related to an enlarged prostate, such as difficulty starting urination, weak stream, or frequent urination (where licensed and appropriate to the product strength).
• ED with or without urinary symptoms — some people may benefit from daily dosing if both ED and BPH symptoms are present.

3. How Cialis works (mechanism of action)

Tadalafil belongs to a group of medicines called phosphodiesterase type 5 (PDE5) inhibitors. During sexual stimulation, nitric oxide is released in the body. This triggers a chemical pathway that increases levels of cyclic GMP in the smooth muscle of blood vessels in the penis. Higher cyclic GMP helps blood vessels relax and widen, allowing more blood flow and supporting an erection.

Tadalafil works by blocking PDE5, an enzyme that breaks down cyclic GMP. By slowing this breakdown, tadalafil helps maintain cyclic GMP levels, making it easier to achieve and sustain an erection when you are sexually aroused.

Important note: Cialis is not an aphrodisiac. Sexual stimulation is still required for an erection to occur.

4. Pharmacokinetics (how the body processes tadalafil)

Understanding pharmacokinetics can help you plan timing and manage expectations.

• Absorption: Tadalafil is absorbed after oral dosing. Food generally has limited impact on onset, though heavy meals may slightly delay absorption.
• Time to start working: Many people notice effects within about 30 minutes to 1 hour. Some may take longer.
• Peak levels (Tmax): The medicine reaches its highest blood concentration typically within 1 to 2 hours after taking a dose (varies by person).
• Duration: Tadalafil has a long duration of action. For ED, effects may last up to around 36 hours in many individuals.
• Half-life: The elimination half-life is roughly 17 hours, which supports its long-lasting effect.
• Metabolism and excretion: Tadalafil is metabolised primarily in the liver (via CYP3A4 pathways) and eliminated mainly through faeces and urine.

5. Typical use: “as needed” or “daily”

Cialis is available in different dosing regimens. Your choice depends on your needs, how often you expect sexual activity, and whether you also have urinary symptoms.

As-needed dosing (ED)

• Often used before expected sexual activity.
• Common strengths for ED include 10 mg or 20 mg taken prior to sex, as directed.
• Effects can last up to about 36 hours, giving flexibility.

Daily dosing (ED and/or BPH)

• Taken once daily at the same time each day.
• Common strengths include 2.5 mg or 5 mg (where indicated and depending on product and clinician advice).
• Can be suitable if you want more spontaneity or have ongoing ED and/or BPH symptoms.

6. When to take Cialis: timing guidance

Timing affects how quickly you feel effects.

• As-needed: Many people take Cialis about 30 minutes to 1 hour before sexual activity. However, you may still find it helpful later because tadalafil lasts long.
• Daily: Take at roughly the same time every day. If you feel side effects, you may discuss adjusting the time with a healthcare professional.
• Do not exceed the prescribed frequency: Taking more than recommended increases the risk of side effects and interactions.

7. Food interactions: what to eat and avoid

Cialis can be taken with or without food. Food interactions are usually modest:

• Light to moderate meals: Generally no significant effect.
• Heavy or very fatty meals: May delay absorption, which could affect how soon you notice effects.
• Grapefruit or grapefruit juice: While not always strictly prohibited, grapefruit can affect drug metabolism (CYP3A4). If you use it regularly, discuss this with a healthcare professional or pharmacist.

If you notice timing changes, try taking Cialis in a consistent way (same general meal timing) and allow sufficient time before planned activity.

8. Alcohol: effects and safety

Alcohol can affect sexual performance and can also contribute to dizziness, low blood pressure, and reduced ability to achieve an erection. Cialis and alcohol together may increase the risk of:

• Light-headedness or dizziness
• Low blood pressure (particularly if you drink heavily)
• Headache

To reduce risk, consider limiting alcohol, avoid binge drinking, and be careful when standing up if you feel faint.

9. Medicine interactions: important warnings

Do not use with nitrates (serious interaction)

Cialis should not be used with nitrates (such as glyceryl trinitrate/nitroglycerin, isosorbide mononitrate/dinitrate) or “poppers” containing amyl nitrite or similar substances. This combination can cause a dangerous drop in blood pressure.

Alpha-blockers for prostate/bladder or blood pressure

Some medicines used for urinary symptoms (alpha-blockers) or high blood pressure can also lower blood pressure. Cialis may amplify this effect. The interaction risk depends on:

• Which alpha-blocker you take
• Your current dose
• Whether you are stable on the medication

Your healthcare professional may recommend starting with a lower tadalafil dose and careful timing.

Other blood pressure medicines

Cialis can lower blood pressure slightly in some people. If you take antihypertensives, you may need monitoring for dizziness or faintness.

CYP3A4 inhibitors (can increase tadalafil levels)

Certain medicines slow tadalafil breakdown, which can increase tadalafil exposure and side effects. Examples include:

• Some antifungals (e.g., ketoconazole, itraconazole)
• Some antibiotics (e.g., clarithromycin)
• Some antiviral medicines
• Some HIV protease inhibitors

If you take strong CYP3A4 inhibitors, you may need dose adjustments and extra caution.

CYP3A4 inducers (can reduce effectiveness)

Other medicines may speed up tadalafil metabolism and reduce its effect. Examples include:

• Rifampicin
• Some anti-epileptics (e.g., carbamazepine, phenytoin, phenobarbital)
• St John’s wort (hypericum)

Other ED treatments

Do not combine Cialis with other PDE5 inhibitors (such as sildenafil or vardenafil) or with similar “erection” products unless a clinician specifically advises it. This increases the risk of adverse effects without adding clear benefit.

Riociguat (pulmonary hypertension)

Cialis must not be used with riociguat (used in some lung/blood pressure conditions) because of the risk of significant blood pressure changes.

10. Dosing: how Cialis is commonly taken

The right dose depends on your condition, response, and tolerability. The information below is general and should be aligned with the product strength and clinician advice.

ED — as-needed

• Typical starting dose: 10 mg
• Adjustment: may be increased or decreased depending on effect and side effects
• Maximum frequency: do not take more often than recommended in the product instructions

ED — once daily

• Typical starting dose: 2.5 mg once daily or sometimes 5 mg once daily
• When to take: same time each day for steadier effect
• Maximum: follow the labelled maximum daily dose and clinician guidance

BPH — once daily

• Typical starting dose: often 5 mg once daily for BPH symptoms (strengths vary by product)
• Ongoing use: may need continued daily treatment for sustained symptom relief

Missed dose: If taking daily, take it when you remember unless it’s close to the next dose. Don’t double the dose to catch up.

11. Practical use tips for best results

• Allow enough time: Give yourself at least 30 minutes (and often up to 1 hour) before planned sexual activity, even though effects may last longer.
• Use sexual stimulation: Cialis helps the body respond—arousal is still required.
• Stay aware of side effects: If you feel dizzy or flushed, avoid driving and consider resting until you feel normal.
• Be consistent with timing/food: If a heavy meal delays onset, plan accordingly next time.
• Don’t “stack” doses: More is not better; it increases risk. If the effect isn’t enough, discuss dose adjustments with a healthcare professional.
• Manage expectations: ED can be influenced by stress, cardiovascular health, smoking, alcohol, and other medications. Cialis can help, but it may not overcome all causes.

12. Safety profile: common and serious side effects

Common side effects

Many side effects are mild and may improve as your body adjusts. Commonly reported effects include:

• Headache
• Flushing (warmth/redness)
• Indigestion or stomach discomfort
• Back pain or muscle aches
• Nasal congestion (blocked nose)
• Dizziness

Seek urgent medical help if you experience these

• Chest pain or symptoms suggesting heart problems, especially if you’ve taken any nitrate medicines.
• Sudden vision changes (including loss of vision) or severe eye pain.
• Sudden hearing changes (including ringing in the ears or hearing loss).
• Priapism: an erection lasting 4 hours or more (unrelated to sexual stimulation). This is an emergency.
• Severe allergic reaction: swelling of the face/lips, difficulty breathing, or widespread rash.

Who should be extra cautious

Discuss suitability with a healthcare professional if you have:

• Heart disease, a recent heart attack or stroke, or unstable angina
• Low blood pressure (or fainting episodes)
• Severe liver or kidney problems
• Certain eye conditions (e.g., non-arteritic anterior ischaemic optic neuropathy in the past)
• Blood disorders that increase the risk of priapism
• Anatomical penile conditions (e.g., Peyronie’s disease)

If Cialis is not safe for you, your clinician may recommend another treatment approach.

13. Alcohol and medicine interactions: practical “at-a-glance” safety

14. Alternative options

If Cialis isn’t suitable or doesn’t work well enough, there are several alternative approaches. The best option depends on your health, preferences, and the cause of ED.

Other PDE5 inhibitors

• Sildenafil (e.g., Viagra) — typically shorter acting than tadalafil.
• Vardenafil — similar class with differing timing and onset.
• Avanafil — often a shorter “as-needed” option with faster onset for some people.

Other ED treatments

• Daily lifestyle support: reduce smoking, manage weight, increase activity, limit alcohol, and improve sleep.
• Psychosexual support: stress and anxiety can contribute; counselling may help.
• Vacuum erection devices (pump systems) — can be effective and non-systemic.
• Intra-cavernosal therapies (injection medicines) — used under clinical guidance.
• Intra-urethral alprostadil — option for some people.
• Surgery (penile implants) — for selected cases when other treatments fail.

BPH symptom options

If you are using tadalafil for urinary symptoms, alternatives for BPH may include alpha-blockers, 5-alpha-reductase inhibitors, or other treatments depending on your profile—your clinician can guide you.

15. UK market and legal/regulatory context (pharmacy and safety)

In the United Kingdom, tadalafil products are regulated as medicines. Online medicine supply should only come from legitimate, authorised sources. Reputable pharmacies follow UK rules for medicine supply and patient safety, including appropriate checks to reduce risks from interactions and unsuitable medicines.

Cialis/tadalafil products must meet UK regulatory standards for quality, safety and supply. If you are considering an online purchase, look for signs of a properly licensed pharmacy and clear information about the product, strength, and delivery.

16. Recent guidance and clinical considerations (what to know now)

Guidance and best practice in the UK continue to emphasise:

• Safety screening for cardiovascular risk, especially for ED treatments.
• Interaction checks, particularly with nitrates, riociguat, and certain blood pressure medicines.
• Recognising red flags such as priapism or sudden vision/hearing problems.
• Choosing an appropriate regimen (as-needed vs daily) based on your pattern of sexual activity and symptoms.

If you have had heart problems or take multiple medicines, it’s wise to review your medicine list with a healthcare professional or pharmacist before starting tadalafil.

17. Delivery and availability in the UK

Availability of specific Cialis strengths can vary. When ordering through a UK online pharmacy, delivery times typically depend on stock availability and the courier service used. Many pharmacies offer tracked delivery options and provide dispatch updates.

• Check product strength: ensure you select the correct dose (e.g., 2.5 mg, 5 mg, 10 mg, 20 mg).
• Packaging: medicines are usually supplied in original packaging to maintain traceability and safe storage.
• Cold/heat considerations: store at room temperature and keep away from excessive heat and moisture.

If you need your medicine quickly for a specific date, check estimated dispatch and delivery times at checkout.

18. Storage and handling

• Keep out of sight and reach of children.
• Store according to the label instructions on the pack (usually at room temperature).
• Do not use after the expiry date.
• Return any unused tablets to a pharmacist for safe disposal (follow local guidance).

19. FAQ

How long does Cialis last?

For erectile dysfunction, tadalafil commonly provides effects for up to about 36 hours. Individual response varies, so plan based on your own experience.

How quickly will Cialis work?

Many people notice it within 30 minutes to 1 hour. Some may take longer. Because tadalafil lasts long, you can still get benefit later, but it’s best to follow recommended timing.

Can I take Cialis with food?

Yes. Cialis can be taken with or without food. Very heavy meals may delay onset slightly, so timing may feel different if you eat a large meal.

Is it safe to drink alcohol while taking Cialis?

Moderate alcohol may be tolerated by some people, but alcohol can worsen dizziness and low blood pressure and affect sexual performance. Avoid heavy drinking and be cautious if you feel light-headed.

Can I take Cialis with nitrates?

No. Cialis must not be used with nitrates (or “poppers”) because it can cause a dangerous fall in blood pressure.

What if it doesn’t work for me?

ED can have many causes. Consider:

• Using the correct dose and giving enough time before sex
• Avoiding heavy meals close to dosing if onset feels delayed
• Reviewing other medicines that may interfere
• Addressing lifestyle factors and stress

If Cialis is consistently ineffective, discuss options with a healthcare professional.

Can women take Cialis?

Cialis is generally indicated for men for ED and for certain BPH-related symptoms. Women should not take Cialis unless specifically advised by a healthcare professional for an appropriate indication.

What should I do if I get side effects?

Mild headaches, flushing, indigestion, or back pain may improve. If side effects are severe, persistent, or you feel faint, seek medical advice promptly. Stop using and seek urgent care for serious symptoms such as priapism (erection lasting 4 hours or more) or sudden vision/hearing changes.

Is it okay to drive after taking Cialis?

If you experience dizziness or low blood pressure, avoid driving. Many people can drive safely, but always check how you personally respond to tadalafil—especially after your first dose.

Can I take Cialis every day?

Daily dosing may be appropriate for some people with ED and/or urinary symptoms. Use the dose and frequency stated for the product and your healthcare advice.

How do I store Cialis?

Store in a safe place at room temperature, away from moisture and direct sunlight, and keep out of reach of children. Use before the expiry date on the pack.

Final reminder

Cialis (tadalafil) can be a convenient treatment for ED and, for some people, for BPH symptoms. For best results, use the right dose and timing, avoid unsafe interactions (especially nitrates), and seek medical advice if you have cardiovascular disease, severe liver/kidney problems, or experience warning symptoms such as priapism or sudden changes in vision or hearing.