How to Safely Stop Cialis (Tadalafil): A Clinician-Backed Discontinuation Protocol

Do you need to taper off Cialis?

The Cialis label gives these regimens: 10 mg before sexual activity as needed, adjusted to 5 or 20 mg by response and tolerability, or 2.5 mg once daily for ED (increased to 5 mg), or 5 mg once daily for BPH and for ED with BPH [1]. It gives no step-down schedule for stopping any of them.

Tadalafil's mean terminal half-life is 17.5 hours in healthy subjects — roughly four times sildenafil's half-life of about 4 hours [1]. Once-daily dosing reaches steady state within 5 days, with exposure about 1.6 times that of a single dose [1]. With a 17.5-hour half-life, blood levels halve roughly every 17.5 hours after the last tablet, so five half-lives is about 87 hours, or roughly three and a half days.

What happens after the last dose

The label's measure of duration is functional: a dose improves erectile function compared with placebo for up to 36 hours, which does not mean a continuous erection, because sexual stimulation is still required [1]. The label says once-daily Cialis provides continuous plasma tadalafil levels and that physicians should consider this when evaluating interactions with nitrates, alpha-blockers, antihypertensives, potent CYP3A4 inhibitors and substantial alcohol [1].

Stopping Cialis for ED

In an integrated analysis of five 12-week placebo-controlled trials in 1,112 men, tadalafil 20 mg as needed improved the erectile function domain of the IIEF by a mean 7.9 points, 75% of intercourse attempts were successful and 81% of men reported improved erections versus 35% on placebo [3]. Those results were measured during treatment.

The REACTT trial randomized 423 men aged 68 or younger after nerve-sparing prostate surgery to tadalafil 5 mg once daily, tadalafil 20 mg on demand or placebo for 9 months, followed by a 6-week drug-free washout. After the washout, 20.9%, 16.9% and 19.1% of the three groups had an erectile function domain score of 22 or higher; the odds ratios versus placebo were 1.1 for once daily and 0.9 for on demand, neither significant [4]. That is a post-surgery population and does not describe men stopping Cialis for other reasons.

Daily Cialis for BPH

Cialis 5 mg once daily is approved for the signs and symptoms of BPH and for ED with BPH [1]. In a 12-week trial of 161 men on tadalafil 5 mg and 164 on placebo, total IPSS fell 5.6 points versus 3.6, a difference apparent at week 1 and significant by week 4, while peak urine flow and post-void residual did not improve significantly [5]. A larger dose-finding study of 1,058 men found IPSS falls of 4.9 points with 5 mg versus 2.3 with placebo [6].

If Cialis is started together with finasteride for BPH, the label recommends that combination for up to 26 weeks, because the extra benefit of Cialis shrinks from week 4 to week 26 and beyond 26 weeks is unknown [1]. In the trial behind that limit, IPSS fell 5.5 points with tadalafil plus finasteride versus 4.5 with placebo plus finasteride at 26 weeks [7].

Side effects that prompt people to stop

The label's discontinuation figures: 3.1% of men on as-needed tadalafil 10 or 20 mg for ED stopped for adverse events versus 1.4% on placebo [1]. For once-daily tadalafil for ED it was 4.1% versus 2.8% [1]. In the BPH and ED/BPH trials it was 3.6% versus 1.6%, with headache, upper abdominal pain and myalgia the reactions that led at least two men on tadalafil to stop [1]. In those BPH trials, headache was reported by 4.1% on tadalafil 5 mg versus 2.3% on placebo, and dyspepsia by 2.4% versus 0.2% [1].

Back pain and myalgia have a characteristic timing: they generally began 12 to 24 hours after a dose and typically resolved within 48 hours, and about 0.5% of men taking as-needed tadalafil stopped because of back pain or myalgia [1].

Nitrates and other interactions

Nitrates are contraindicated with Cialis, taken regularly or intermittently [1]. The 48-hour figure in the label is an emergency rule, not a routine washout: where a nitrate is medically necessary in a life-threatening situation, at least 48 hours should pass after the last Cialis dose, and the nitrate should still be given only under close medical supervision with hemodynamic monitoring [1].

A crossover study of 150 men looked at the time course: they took tadalafil 20 mg or placebo daily for 7 days and then sublingual nitroglycerin 0.4 mg. Standing systolic blood pressure fell below 85 mm Hg in more men on tadalafil at 4, 8 and 24 hours, with no difference at 48, 72 and 96 hours [8]. The authors concluded the interaction lasted about 24 hours and that tadalafil should not be combined with organic nitrates [8].

CYP3A4 inhibitors raise tadalafil exposure: ketoconazole 400 mg daily raised tadalafil 20 mg AUC by 312% [1]. With a potent inhibitor the label caps as-needed Cialis at 10 mg every 72 hours and once-daily Cialis at 2.5 mg [1].

Vision and hearing changes

Two label instructions are stop-and-seek-care instructions. The label says patients should stop Cialis and seek medical attention for a sudden loss of vision in one or both eyes, which may be non-arteritic anterior ischemic optic neuropathy (NAION) [1], and should stop and seek prompt medical attention for a sudden decrease or loss of hearing, which may come with tinnitus and dizziness [1].

NAION has been reported rarely after marketing with all PDE5 inhibitors, and two observational case-crossover studies suggested roughly a twofold risk (estimates 2.15, 95% CI 1.06 to 4.34, and 2.27, 95% CI 0.99 to 5.20); the label states that neither the reports nor these studies establish a causal relationship [1]. The label also gives NAION's background annual incidence, 2.5 to 11.8 cases per 100,000 in men aged 50 and older [1]. For hearing, a cross-sectional survey of 11,525 US men aged 40 and older found self-reported hearing impairment associated with sildenafil use (OR 2.05, 95% CI 1.23 to 3.43) but not with tadalafil (OR 1.40, 95% CI 0.49 to 4.04) [9].

Adcirca is a different product

Adcirca is a separate tadalafil product for pulmonary arterial hypertension, sold as 20 mg tablets [2]. Cialis also has a 20 mg tablet, but its indications and dosing differ [1][2]. A person should not take both, since both are tadalafil [1][2]. The taper question on this page is about Cialis doses for ED and BPH.