How quickly does Cialis (tadalafil) start working?
Reviewed by the glpzoom Editorial Team against primary clinical sources — FDA labeling, peer-reviewed trials, and specialty-society guidelines.
Content current as of June 2026; updated when guidance or availability changes.
Tadalafil (brand name Cialis) typically begins working within 30 minutes of taking an as-needed dose (10-20mg), with peak blood level around 2 hours after dosing. The clinical effect lasts up to 36 hours — substantially longer than sildenafil's 4-6 hours. Food does not significantly affect tadalafil absorption (unlike sildenafil, which a high-fat meal can slow). The long duration means tadalafil can be taken in the morning for activity later in the day or evening without needing to time precisely. For daily low-dose tadalafil (2.5-5mg), continuous blood levels mean no specific 'onset' — the medication is always active. Side effects (headache, facial flushing, indigestion, muscle aches) typically appear within the same window as the therapeutic effect. As with all PDE5 inhibitors, response requires sexual stimulation — tadalafil does not cause an erection without arousal.
Where to start
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Hims
from $13/mo- Best for cash-pay
- Best for speed
Hims ED — generic sildenafil from $13/mo
Ro
from $2/mo- Best for clinical oversight
Ro — original online ED brand, sildenafil & tadalafil
Drugs referenced
Related questions
Sildenafil vs tadalafil: which is better?
Sildenafil and tadalafil are both PDE5 inhibitors with similar efficacy but different pharmacokinetics. Sildenafil onset is 30-60 minutes with a 4-6 hour duration — useful for planned activity. Tadalafil onset is similar but duration is much longer at up to 36 hours, which is why it's marketed as 'the weekend pill.' Tadalafil also has a daily low-dose formul