Cialis 40 Mg – Tadalafil 40 Mg Tablets

Last Updated on 10/28/2026 ✔ 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

Is 40 mg of Cialis Safe?

Taking 40 mg of Cialis (tadalafil) for erectile dysfunction (ED) is not recommended, as it may increase the risk of serious side effects, including a sudden drop in blood pressure and priapism (a prolonged erection). The usual as-needed dose for ED is 10 mg, while the recommended daily dose is 2.5 mg or 5 mg. The maximum recommended dose for as-needed ED treatment is generally 20 mg within 24 hours.

For certain conditions, such as pulmonary arterial hypertension (PAH), tadalafil may be prescribed at a total dose of 40 mg per day, typically as two 20 mg doses or according to the prescribed regimen. However, this is a different treatment indication from ED, and the dosage should only be taken under appropriate medical supervision.

How Cialis Can Affect Other Parts of the Body

Cialis works by inhibiting the phosphodiesterase type 5 (PDE5) enzyme, helping relax blood vessels and improve blood flow to the penis during sexual stimulation. However, PDE5 is also present in other parts of the body, including the lungs, kidneys, liver, brain, and platelets. This means tadalafil can have effects beyond erectile function.

Tadalafil can also inhibit phosphodiesterase type 11 (PDE11), an enzyme found in several tissues, including:

• Heart
• Pancreas
• Pituitary gland
• Skeletal muscles
• Testes
• Corpus cavernosum: One of the two columns of spongy tissue inside the penis that fill with blood during an erection.

Because tadalafil affects enzymes and blood vessels in different parts of the body, taking more than the recommended dose may increase the risk of adverse effects. Always consult a qualified healthcare professional before changing your dosage.

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.

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.

Antifungals (ketoconazole, itraconazole) and antibiotics (rifampin) – these can affect how the body processes tadalafil, either raising or lowering its levels. Your dose may need adjustment.

HIV protease inhibitors (ritonavir) — can increase tadalafil levels in the body; a dose reduction may be necessary.

Always give your doctor and pharmacist a complete list of everything you take prescription, over-the-counter and herbal, so they can check for interactions before you start tadalafil.

Cialis vs. Viagra

Cialis (tadalafil) and Viagra (sildenafil) are both PDE5 inhibitors used to treat erectile dysfunction, but they differ in several practical ways that can influence which one suits a particular person.

Both medicines work through the same PDE5 inhibition mechanism and have similar overall effectiveness. The main practical difference is duration: tadalafil’s long window allows more spontaneity, while sildenafil’s shorter window requires closer timing to sexual activity. Sildenafil is more affected by food, so it is usually taken on an empty stomach, whereas tadalafil can be taken with a meal without materially changing how quickly it works. Side-effect profiles overlap — headache, flushing, indigestion and nasal congestion are common to both — but sildenafil is more associated with temporary visual disturbances, while tadalafil is more associated with back pain and muscle aches. The choice between them is a clinical one based on your health, preferences and other medications.

Cialis vs. Vardenafil

Vardenafil (formerly sold as Levitra) is another PDE5 inhibitor for ED. Like sildenafil, it has a relatively short duration of action compared with tadalafil.

Tadalafil and vardenafil share the same mechanism of action, but tadalafil’s much longer half-life gives it a far longer window of effectiveness. Vardenafil, like sildenafil, is best taken on an empty stomach because fatty food can delay its absorption, while tadalafil can be taken with or without food. Both are effective for ED; the main difference is how long the effect lasts and how much flexibility that gives you around the timing of sexual activity. Vardenafil has been reported to have a slightly greater effect on the QT interval (a heart-rhythm measurement) than tadalafil, which may be relevant for men with certain heart conditions — something to discuss with a doctor.

Cialis and Alcohol

Both tadalafil and alcohol lower blood pressure. When taken together, their blood-pressure-lowering effects can add up, increasing the risk of dizziness, lightheadedness, fainting and symptomatic hypotension. Excessive alcohol can also independently worsen erectile function, which works against the reason you are taking tadalafil in the first place.

A small amount of alcohol is not an absolute contraindication, but the safest approach is to limit alcohol intake while taking tadalafil. Heavy or binge drinking should be avoided. If you have questions about how much is safe for you specifically, ask your healthcare professional — the answer depends on your overall health, other medications and individual risk factors. Food and alcohol are not the same consideration with tadalafil: food has minimal impact on how the medicine works, but alcohol can interact meaningfully.

Alternatives to Cialis

Cialis is not the only treatment option for ED. Alternatives fall into several categories:

Other PDE5 inhibitors:

• Sildenafil (Viagra) — the original ED pill, with a shorter 4–6 hour window and lower cost as a generic
• Vardenafil (Levitra) — similar to sildenafil in duration and effect
• Avanafil (Stendra) — a newer option with a faster onset (15–30 minutes) and a 6–12 hour duration

Non-medication options:

• Vacuum erection devices — a mechanical pump that draws blood into the penis
• Penile injections — medication injected directly to produce an erection
• Penile implants — a surgical option for men who do not respond to other treatments
• Testosterone therapy — only appropriate if low testosterone is an underlying cause

Lifestyle and underlying-cause approaches:

• Addressing cardiovascular risk factors (blood pressure, cholesterol, weight, smoking)
• Managing diabetes, which is a common contributor to ED
• Reducing alcohol and recreational drug use
• Counselling or therapy when psychological factors play a role

The right alternative depends on the cause of ED, your overall health and your preferences. A healthcare professional can help identify the underlying reason and recommend the most suitable option.

Cost

The cost of tadalafil varies depending on whether you choose the brand-name product (Cialis) or a generic, the dose, the quantity and the pharmacy. In general:

• Generic tadalafil is significantly cheaper than brand-name Cialis, as the patent has expired in many markets including Australia.
• Daily low-dose tadalafil (2.5–5 mg) may cost less per tablet than on-demand doses (10–20 mg) because the tablets are lower strength, though daily use means taking it every day.
• Larger pack sizes typically reduce the per-unit cost, but only buy what you will use before the expiry date.

In Australia, tadalafil is a prescription-only medicine, so pricing also depends on whether a particular product is listed on the Pharmaceutical Benefits Scheme (PBS) for your indication. ED treatment is not always a PBS-subsidised benefit, so out-of-pocket costs can vary. Check with your pharmacist for current pricing and any subsidy that may apply to your situation. The prices shown in the dosage table above are indicative only and may change.

Pregnancy

Cialis (tadalafil) is not indicated for use in women. There are no adequate and well-controlled studies of tadalafil use in pregnant women. Animal reproduction studies did not show evidence of fetal harm, but the absence of human data means tadalafil should not be used during pregnancy. If you are pregnant, planning to become pregnant, or think you may be pregnant, speak with a healthcare professional before taking any medication — not just tadalafil.

Birth Control Needs

Tadalafil does not prevent pregnancy and does not act as a form of contraception. It also does not protect against sexually transmitted infections, including HIV. If you are sexually active and need to prevent pregnancy or protect against STIs, you must use appropriate contraception and barrier methods independently of tadalafil. Discuss your contraceptive needs with a healthcare professional.

Breastfeeding

Tadalafil is not indicated for use in women, and there are no data on the presence of tadalafil and/or its metabolites in human breast milk. Animal studies have shown that tadalafil and/or its metabolites are present in the milk of lactating rats at concentrations higher than in maternal plasma. Because a drug present in animal milk is likely to be present in human milk, and the effects on a nursing infant are unknown, tadalafil should not be used while breastfeeding. If you are breastfeeding or planning to breastfeed, speak with your healthcare professional before taking any medication.

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.