Tadalafil Dosage and How Long It Lasts

Understanding tadalafil dosage and duration helps set realistic expectations for treatment. This guide explains available doses, how long tadalafil remains active, what factors affect duration, and why only a doctor can determine appropriate dosing for individual circumstances.

Available Tadalafil Doses

Tadalafil is available in the UK in four main strengths:

• 2.5mg: Lowest strength, typically for daily use
• 5mg: Used for both daily and on-demand treatment
• 10mg: Standard starting dose for on-demand use
• 20mg: Maximum dose for on-demand treatment

Each strength serves different treatment approaches and individual needs.

Daily vs On-Demand Dosing

Daily Low-Dose Regimen

For continuous treatment:

• 2.5mg or 5mg taken once daily
• Same time each day recommended
• Builds up steady levels in the body
• Allows spontaneous sexual activity
• May take several weeks for full effect

On-Demand Higher Doses

For intermittent use:

• 10mg or 20mg taken before sexual activity
• At least 30 minutes before, ideally 1-2 hours
• No more than once per 24 hours
• Effects last up to 36 hours

For detailed information on daily dosing, see our guide on tadalafil 5mg daily treatment.

How Long Does Tadalafil Last?

Duration of Effect

Tadalafil is notable for its long duration compared to other ED medications:

On-Demand Doses (10mg, 20mg):

• Effects can last up to 36 hours
• Sometimes called the “weekend pill”
• Doesn’t mean constant erection for 36 hours
• Means ability to achieve erection within this window when sexually stimulated

Daily Doses (2.5mg, 5mg):

• Maintains steady levels continuously
• Effectiveness doesn’t follow the same time-limited pattern
• Works as long as daily dosing continues

Individual Variation

Duration varies between individuals based on:

• Metabolism speed
• Age
• Liver and kidney function
• Other medications
• Overall health status
• Dose taken

Some men find effects diminish before 36 hours; others may notice effects lasting the full duration or even slightly longer.

Understanding Tadalafil Half-Life

What Is Half-Life?

Half-life refers to the time it takes for half the medication to be eliminated from the body. For tadalafil:

• Half-life is approximately 17.5 hours
• This long half-life explains the extended duration of effect
• Varies based on individual factors

What Half-Life Means Practically

• After 17.5 hours, roughly half the dose remains active
• After 35 hours, roughly a quarter remains
• Complete elimination takes about 5 half-lives (approximately 88 hours)
• This extended presence allows the “up to 36 hours” effectiveness window

Comparison with Other ED Medications

Tadalafil’s half-life is notably longer than:

• Sildenafil (Viagra): approximately 4 hours
• Vardenafil (Levitra): approximately 4-5 hours

This difference explains why tadalafil offers more prolonged effects.

Factors Affecting Tadalafil Duration

Age

• Older individuals may experience longer duration
• Metabolism typically slows with age
• Doctors may adjust dosing accordingly

Liver Function

• Liver processes and eliminates tadalafil
• Reduced liver function extends duration
• May require dose adjustment

Kidney Function

• Kidneys also play a role in elimination
• Impaired kidney function can prolong effects
• Medical assessment determines appropriate dosing

Other Medications

Some medications affect how long tadalafil lasts:

• CYP3A4 inhibitors (some antibiotics, antifungals) can increase tadalafil levels
• CYP3A4 inducers (some seizure medications) can decrease tadalafil levels
• Always inform prescribers of all medications

Food and Alcohol

• Food doesn’t significantly affect tadalafil absorption (unlike some ED medications)
• Heavy, fatty meals might slightly delay effects
• Excessive alcohol may reduce effectiveness

Onset of Action

How Quickly Does Tadalafil Start Working?

On-Demand Doses:

• Effects may begin as early as 16-30 minutes
• Most men notice effects within 30-60 minutes
• Maximum effect typically occurs around 2 hours
• Timing varies individually

Daily Doses:

• Steady-state levels achieved after several days
• Full therapeutic effect may take 4-8 weeks
• Less about specific onset, more about maintaining levels

Factors Affecting Onset

• Empty vs full stomach (minor effect)
• Individual metabolism
• Dose taken
• Sexual stimulation (required for tadalafil to work)

Dosing Frequency Limitations

Maximum Frequency

On-Demand Dosing:

• Maximum one dose per 24 hours
• Typically, 10mg or 20mg every 24 hours at most
• More frequent dosing increases side effect risk

Daily Dosing:

• One 2.5mg or 5mg tablet daily
• Consistent timing preferred
• Don’t double up for missed doses

Why These Limits Exist

• Prevents excessive blood levels
• Reduces side effect risk
• Avoids potential for priapism (prolonged erection)
• Ensures safe blood pressure effects

Who Determines Appropriate Dosage?

Medical Assessment Required

Only qualified healthcare professionals can prescribe tadalafil dosage because they must consider:

• Complete medical history
• Current health conditions
• All medications and supplements
• Kidney and liver function
• Cardiovascular health
• Previous response to ED treatment
• Individual risk factors

Why Self-Dosing Is Dangerous

Determining your own dose without medical oversight risks:

• Dangerous drug interactions
• Cardiovascular complications
• Excessive side effects
• Inadequate treatment
• Missing underlying serious conditions

Dose Adjustments

Doctors may adjust dosing based on:

• Initial treatment response
• Side effect profile
• Changes in health status
• New medications started
• Patient preference between daily and on-demand

Special Dosing Considerations

Older Adults

• May start on lower doses (5mg or 10mg on-demand)
• Half-life can be slightly longer
• More likely to have conditions affecting dosing
• Require careful medical assessment

Kidney Impairment

• May require dose reduction
• Maximum recommended dose may be lower
• More frequent monitoring needed

Liver Impairment

• Mild to moderate impairment: may use 10mg maximum
• Severe impairment: not recommended
• Individual assessment essential

Concurrent Alpha-Blocker Use

• May require lower initial tadalafil dose
• Gap between medications may be recommended
• Close monitoring for blood pressure effects

Daily vs On-Demand: Duration Considerations

Choosing Based on Sexual Activity Frequency

Daily dosing may suit those who:

• Have sexual activity more than twice weekly
• Prefer spontaneity
• Want continuous treatment

On-demand may suit those who:

• Have less frequent sexual activity
• Prefer not taking daily medication
• Can plan around the medication window

The long 36-hour duration of on-demand tadalafil offers flexibility that some men prefer over daily medication.

Tadalafil for BPH: Different Dosing

When prescribed for benign prostatic hyperplasia (BPH):

• Usually 5mg once daily
• May also address ED if present
• Taken regardless of sexual activity plans
• Requires same medical supervision

What to Do About Missed Doses

Daily Regimen

• Take when remembered, unless nearly time for next dose
• Don’t take two doses to make up for missed dose
• If frequently forgetting, on-demand approach might suit better

On-Demand

• Simply take before next planned sexual activity
• Maintain 24-hour minimum between doses
• Missing an on-demand dose has no continuing effect

Frequently Asked Questions

Why does tadalafil last so much longer than other ED medications?

Tadalafil’s chemical structure gives it a longer half-life (about 17.5 hours) compared to sildenafil or vardenafil (about 4-5 hours). This extended half-life translates to a longer window of effectiveness.

Does tadalafil work better on an empty stomach?

Food has minimal effect on tadalafil absorption, unlike sildenafil which is affected by fatty meals. You can take tadalafil with or without food, though very heavy meals might slightly delay onset.

Can I take a higher dose if it’s been over 36 hours?

Always wait at least 24 hours between on-demand doses, regardless of whether effects have fully worn off. If you feel you need more frequent dosing, discuss daily low-dose treatment with your doctor rather than increasing frequency.

How do I know which tadalafil dose is right for me?

Only a doctor can determine appropriate dosing based on your complete medical profile, health conditions, other medications, and individual response. Don’t try to determine this yourself.

Does tadalafil build up in the system with daily use?

With daily dosing, tadalafil does reach steady-state levels after several days of consistent use. This is intentional and part of how daily treatment works. It’s not harmful accumulation but rather therapeutic levels being maintained.

If tadalafil lasts 36 hours, why do some people take it daily?

Daily low-dose tadalafil (2.5mg or 5mg) maintains steady levels for spontaneity and may suit those with frequent sexual activity. On-demand higher doses (10mg or 20mg) taken intermittently suit those with less frequent sexual activity. Different approaches for different needs.

Related Information

For more context about tadalafil treatment:

• Tadalafil 5mg Daily Overview - Daily treatment approach
• Tadalafil 10mg and 20mg: On-Demand Treatment - Higher-dose intermittent use
• How Does Tadalafil Work? - Mechanism of action
• Tadalafil Side Effects - Safety information