Cialis 40 Mg – Tadalafil 40 Mg Tablets

Last Updated on 09/24/2026 ✔ Medically Reviewed by Dr. Arjun Srivastav

Cialis contains tadalafil, a PDE5 inhibitor used to treat erectile dysfunction and, at specific doses, pulmonary arterial hypertension. A 40 mg tadalafil dose is not a standard as-needed ED dose — lower tadalafil doses are generally used for ED. Tadalafil 40 mg has a specific role in pulmonary arterial hypertension (PAH), where it is taken once daily under medical supervision. A person should not increase their ED dose from 20 mg to 40 mg without medical advice. Higher doses do not automatically produce better results and can increase the risk of side effects.

What Is Cialis 40 mg?

Cialis is a brand-name medicine containing tadalafil, which belongs to the PDE5 inhibitor class of drugs. Tadalafil works by increasing blood flow to specific tissues by inhibiting the PDE5 enzyme, which breaks down a molecule called cGMP that relaxes smooth muscle in blood vessels. For ED, this mechanism increases blood flow to the penis during sexual stimulation. For PAH, the same mechanism relaxes blood vessels in the lungs, reducing pulmonary blood pressure.

The term “Cialis 40 mg” needs clarification because it can mean two very different things depending on context. Cialis as a brand is primarily associated with ED treatment at lower doses. A 40 mg tadalafil regimen, however, is specifically used for PAH and is taken once daily — a fundamentally different treatment approach from on-demand ED use. Confusing the two can lead to dangerous misunderstandings about dosing.

Cialis vs Tadalafil

Cialis is the brand name; tadalafil is the active ingredient. The distinction matters here because a 40 mg tadalafil regimen should not automatically be interpreted as a “40 mg Cialis ED tablet.” Tadalafil 40 mg for PAH is a once-daily treatment prescribed for a specific medical condition, while Cialis for ED uses lower doses taken either on demand or daily. The brand name and the active ingredient are not interchangeable when discussing dose and indication.

Is Cialis 40 mg Used for Erectile Dysfunction?

Standard Tadalafil Doses for ED

Standard clinical guidelines describe tadalafil doses for ED as follows:

• 10 mg: A common on-demand starting dose
• 20 mg: The maximum recommended on-demand dose for ED
• 2.5 mg or 5 mg: Daily low-dose options for men who anticipate frequent sexual activity

On-demand tadalafil is taken before sexual activity, while the daily option is taken every day regardless of timing so that a steady level of medicine supports erectile function at any time. The choice between on-demand and daily treatment depends on individual preference, frequency of sexual activity and medical suitability.

A 40 mg dose is not simply the next step up from 20 mg for ED. The maximum recommended on-demand tadalafil dose for ED is 20 mg. Moving beyond that is not a standard ED dosing decision.

Can You Take 40 mg Tadalafil for ED?

Do not self-increase tadalafil to 40 mg for ED. There are several reasons:

• A higher dose does not automatically mean a better or more reliable erection
• Greater exposure to the medicine increases the risk of adverse effects
• Dose selection depends on individual factors, medical indication and a healthcare professional’s assessment
• If a standard ED dose is not effective, the appropriate response is to consult a doctor — not to increase the dose independently

A clinician may review how the medicine is being used, consider whether another PDE5 inhibitor might suit better, or investigate underlying causes of ED. Simply doubling the dose is not the clinical pathway

What Is Tadalafil 40 mg Used For?

Tadalafil 40 mg for Pulmonary Arterial Hypertension

Pulmonary arterial hypertension (PAH) is a condition characterised by high blood pressure in the arteries of the lungs. The pulmonary arteries become narrowed and thickened, forcing the right side of the heart to work harder to pump blood through the lungs. Over time, this strain can lead to serious complications.

Tadalafil may be prescribed for PAH because the same PDE5 inhibition mechanism that increases penile blood flow for ED also relaxes blood vessels in the lungs. By reducing pulmonary vascular resistance, tadalafil lowers the pressure in the pulmonary arteries and improves blood flow through the lungs.

For PAH, tadalafil 40 mg is taken as a once-daily regimen. This is fundamentally different from ED treatment, where tadalafil is taken on demand before sexual activity (or at a lower daily dose). The 40 mg once-daily PAH regimen is prescribed and monitored by a specialist, and it is not interchangeable with ED dosing.

Why the 40 mg PAH Dose Is Different From ED Dosing

The key difference is the indication and the dosing pattern. ED treatment uses lower doses timed around sexual activity or a low daily dose. PAH treatment uses 40 mg daily as a continuous regimen to manage a chronic cardiovascular condition. The same active ingredient serves very different purposes at very different doses.

Cialis and Tadalafil Dosage in Australia

Tadalafil for Erectile Dysfunction

In Australia, tadalafil for ED is available as both a brand-name product (Cialis) and as a generic medicine. Dosing is determined by a healthcare professional based on the individual’s situation:

• As-needed treatment: 10 mg or 20 mg taken before sexual activity, with a maximum of one dose in 24 hours
• Daily treatment: 2.5 mg or 5 mg taken once daily for men who anticipate frequent sexual activity

Sexual stimulation is required for tadalafil to work for ED. The medicine supports the natural process that begins with stimulation — it does not produce an erection independently.

Tadalafil for BPH/LUTS

Tadalafil can also be used to treat urinary symptoms associated with benign prostatic hyperplasia (BPH), a non-cancerous enlargement of the prostate gland. For this indication, a different dosing regimen applies — typically a low daily dose rather than on-demand use. The mechanism is the same PDE5 inhibition, but the target tissue is the prostate and bladder rather than the penis. BPH treatment with tadalafil is prescribed separately from ED treatment, although some men may have both conditions addressed by a single daily regimen under medical guidance.

Tadalafil 40 mg for PAH

For PAH, the 40 mg once-daily regimen is prescribed by a specialist managing the cardiovascular condition. This is not a dose a person self-selects — it is part of a treatment plan for a serious medical condition, monitored by a healthcare professional.

Why You Shouldn’t Increase Your Dose Yourself

Dose escalation without medical advice is dangerous for several reasons:

• Higher doses increase exposure to the medicine and the risk of side effects
• A dose that seems “too low” may actually be working but being used incorrectly (wrong timing, food interactions, lack of stimulation)
• The underlying cause of ED may need investigation rather than a higher dose
• Combining higher doses with other medicines can lead to serious interactions
• A healthcare professional can identify whether a different medicine or approach is more appropriate

If your current dose is not effective, the correct step is to speak with your doctor or pharmacist — not to take more.

How Does Tadalafil Work?

Tadalafil works through a clear mechanism:

1. Sexual stimulation triggers the release of nitric oxide in the penis
2. Nitric oxide increases levels of cGMP
3. cGMP relaxes the smooth muscle in penile blood vessels
4. Tadalafil inhibits the PDE5 enzyme — the enzyme that breaks down cGMP
5. With PDE5 inhibited, cGMP levels stay higher for longer
6. This allows increased blood flow to the penis, supporting an erection

Tadalafil does not cause an automatic erection. Sexual stimulation is required for its ED effect — the medicine supports the natural process that begins with arousal.

How Long Does Tadalafil Last?

How Long Does Tadalafil Last for ED?

Tadalafil is commonly discussed as having a long duration of effect compared with other PDE5 inhibitors. Its ED effect can last up to 36 hours, which is significantly longer than sildenafil’s 4–6 hour window. This extended duration is one of tadalafil’s main practical distinctions and is the reason it is sometimes called the “weekend pill.”

Does “36 Hours” Mean an Erection Lasts 36 Hours?

No. The 36-hour figure refers to the window during which the medicine remains available to support an erection when sexual stimulation occurs. It does not mean a continuous erection lasting 36 hours. An erection still requires sexual stimulation, and the medicine supports the process during that window. If an erection lasts more than 4 hours, that is a medical emergency (priapism) requiring immediate attention — it is not a sign that the medicine is “working well.”

What Affects How Long Tadalafil Works?

Several factors influence how long tadalafil remains effective:

• Individual response: People metabolise the medicine at different rates
• Dose: Higher doses may extend the duration, but this is a clinical decision, not a self-adjustment
• Other medicines: Some medicines affect how the body processes tadalafil
• Health conditions: Kidney and liver function can affect how long the medicine stays in the body

Cialis 20 mg vs Tadalafil 40 mg

Is 40 mg Twice as Strong as 20 mg?

No. Dose strength should not be interpreted as a simple “twice the effectiveness” relationship. A 40 mg dose does not produce twice the erectile effect of a 20 mg dose. Higher exposure increases the amount of medicine in the body, which raises the risk of side effects, but it does not translate to proportionally better results. The relationship between dose and effect is not linear in this way, which is why dose selection is a clinical decision rather than a simple arithmetic step.

Cialis 40 mg Side Effects

Like other medicines containing tadalafil, Cialis may cause side effects. The likelihood can depend on the dose, medical condition and individual response. For additional information about potential adverse effects and precautions, see our detailed article on Cialis side effects and precautions.

When Should You Seek Urgent Medical Attention?

Seek emergency medical help immediately if you experience:

• An erection lasting more than 4 hours
• Sudden vision loss or major vision changes
• Sudden hearing loss or hearing changes
• Chest pain, irregular heartbeat or fainting
• Severe allergic reaction symptoms
• Any severe or rapidly worsening symptom after taking tadalafil

Cialis 40 mg Drug Interactions

Nitrate Medicines

Tadalafil must not be taken with nitrate medicines. The combination can cause a dangerous, potentially life-threatening drop in blood pressure. Nitrates include nitroglycerin, isosorbide mononitrate, isosorbide dinitrate and amyl nitrate or nitrites (“poppers”). If you take any nitrate medicine, tadalafil is contraindicated — this is the most critical interaction to be aware of.

Alpha-Blockers and Blood Pressure Medicines

Alpha-blockers, used to treat high blood pressure and prostate conditions, can interact with tadalafil and increase the risk of low blood pressure and dizziness. If both medicines are prescribed, a healthcare professional may adjust the timing or dose and monitor the combination. Other blood pressure medicines may also require review, as tadalafil itself has a blood-pressure-lowering effect.

Other PDE5 Inhibitors

Do not combine tadalafil with other PDE5 inhibitors such as sildenafil, vardenafil or avanafil. Using more than one ED medicine at the same time increases the risk of side effects without improving results.

Alcohol

Excessive alcohol can affect erectile function independently and worsen dizziness and low blood pressure when combined with tadalafil. Both alcohol and tadalafil lower blood pressure, so combining them increases the risk of symptomatic hypotension. Discuss alcohol use with your healthcare professional rather than assuming the combination is risk-free.

Other Medicines and Supplements

Always provide your healthcare professional or pharmacist with a complete list of all medicines you take, including prescription, over-the-counter and herbal products. Some medicines can affect how tadalafil is processed by the body, and some supplements may interact in ways that are not immediately obvious.

Who Should Talk to a Doctor Before Taking Tadalafil?

Speak with a healthcare professional before taking tadalafil if you have or have had any of the following:

• Cardiovascular disease: Including recent heart attack, stroke, unstable angina or other serious heart conditions
• Blood-pressure problems: Very low or poorly controlled blood pressure
• Kidney disease: Renal impairment affects how the body clears tadalafil and may require dose adjustment
• Liver disease: Hepatic impairment affects metabolism and may require dose adjustment or avoidance
• Previous serious cardiovascular events: A history of significant heart or vascular events requires assessment
• Other medications: Any prescription, over-the-counter or herbal medicines, particularly nitrates and alpha-blockers
• Older adults: People over 65 metabolise medicines more slowly and should initiate treatment cautiously
• Anyone already using PDE5 inhibitors: Do not start tadalafil if you are already taking another ED medicine

A healthcare professional must assess your suitability before you start taking tadalafil. This is not a formality — it is a clinical safety assessment based on your full health picture.

Cialis 40 mg in Australia: Prescription & Regulatory Information

Is Cialis Prescription-Only in Australia?

Yes. Tadalafil, whether as the brand Cialis or as a generic, is a prescription-only medicine in Australia. This means it can only be obtained with a valid prescription from a qualified healthcare professional. It is not available over the counter.

How Australian Dosing Differs by Medical Condition

In Australia, tadalafil dosing follows the same principles as international clinical guidelines:

• ED (on demand): 10 mg or 20 mg before sexual activity
• ED (daily): 2.5 mg or 5 mg once daily
• BPH/LUTS: Condition-specific dose, typically 5 mg daily
• PAH: 40 mg once daily under specialist supervision

The dose is tied to the medical condition being treated. A prescription for one indication does not automatically transfer to another.

Why TGA/Healthdirect Information Matters

The Therapeutic Goods Administration (TGA) regulates medicines in Australia and provides authoritative information about approved medicines, their indications and their safe use. Healthdirect, the Australian government-funded health information service, offers consumer-friendly guidance on tadalafil and other medicines. For anyone in Australia seeking reliable information about tadalafil dosing, safety and regulatory status, the TGA and Healthdirect are the primary authoritative sources. Always refer to these sources for the most current Australian-specific guidance.

Can Cialis 40 mg Be Taken With Food?

Tadalafil can be taken with or without food. Unlike sildenafil, where a high-fat meal can delay absorption, food does not significantly affect tadalafil’s absorption or onset. This means tadalafil can be taken with a meal without materially changing how quickly it works.

The food question is distinct from the alcohol question. While food has minimal impact on tadalafil, alcohol can interact meaningfully — both tadalafil and alcohol lower blood pressure, and combining them increases the risk of dizziness and symptomatic hypotension. Food and alcohol are not the same consideration and should be treated separately.

What Happens If You Take Too Much Tadalafil?

Taking more than the prescribed dose does not improve results and increases the risk of adverse effects. Signs of excessive tadalafil exposure can include:

• Severe dizziness
• Fainting
• Prolonged or painful erection
• Severe headache
• Nausea
• Vision or hearing changes

If you suspect you have taken too much tadalafil, seek medical advice or contact the Poisons Information Centre (13 11 26 in Australia) immediately. For severe symptoms such as chest pain, prolonged erection or fainting, go to an emergency department. Do not wait for symptoms to resolve on their own.

Cialis 40 mg Storage and Disposal

How to Store Tadalafil

Store tadalafil at room temperature in a cool, dry place away from direct sunlight and moisture. Keep the medicine in its original packaging until needed. Keep out of reach of children.

Expiry Date

Do not take tadalafil after the expiry date printed on the packaging. Expired medicine may not work as intended and can be less predictable. If you have expired tadalafil, dispose of it appropriately rather than taking it.

Disposal in Australia

In Australia, unused or expired medicines should not be thrown in the household bin or flushed down the toilet. Return them to a pharmacy, where they can be disposed of safely through the Return Unwanted Medicines program. This is a free, nationwide service available at most Australian pharmacies.

Cialis 40 mg vs Other Tadalafil Strengths

This table reflects standard clinical dosing. Products marketed as “Cialis 60 mg” or “Cialis 80 mg” are not official Cialis strengths and do not correspond to standard tadalafil dosing for any approved indication. Do not treat non-standard strengths as legitimate dose options without medical advice.

Key Takeaways

• Cialis contains tadalafil, a PDE5 inhibitor used for ED and, at specific doses, PAH
• 40 mg is not the standard ED dose — the maximum recommended on-demand ED dose is 20 mg
• Tadalafil 40 mg has a specific role in PAH treatment as a once-daily regimen
• Never increase tadalafil dosage without medical advice — higher doses increase risk without guaranteeing better results
• Nitrates must not be combined with tadalafil under any circumstances

Medical disclaimer: This information is for educational purposes only and does not replace professional medical advice, diagnosis or treatment. Always consult a qualified healthcare professional before starting, stopping or changing any medication. Never self-prescribe or alter your dose without medical supervision.

Sources & medical references: Therapeutic Goods Administration (TGA); Healthdirect Australia; Australian Product Information and Consumer Medicines Information (CMI) where applicable; European Association of Urology (EAU) Guidelines; American Urological Association (AUA) Guidelines.