Tadalafil Side Effects: Common, Serious and Long-Term

The Cialis label's side effect tables by dose and schedule, the delayed back pain pattern, and what is known about vision, hearing and two years of daily use.

The most common tadalafil side effects in the Cialis label's trials are headache, indigestion (dyspepsia), back pain, muscle aches, nasal congestion and flushing, and they are dose-related: in as-needed ED trials headache was reported by 15% of men on 20 mg, 11% on 10 mg and 5% on placebo.¹ Serious problems are rare but real: an erection lasting more than four hours needs emergency care, and sudden loss of vision or hearing means stopping and getting medical help at once.¹ This article reads the label's tables and the long-term and eye-safety studies so the common and the serious effects can be told apart.

What are the most common side effects of tadalafil?

The label reports adverse reactions in 2% or more of men and more frequent than on placebo. Rates depend on the dose and the schedule, so the table separates them.¹

These came from eight 12-week placebo-controlled studies in men with a mean age of 59. The discontinuation rate due to adverse events was 3.1% on 10 or 20 mg, compared with 1.4% on placebo.¹ Most men in these trials did not stop the drug for side effects. See our pages on tadalafil 10 mg and tadalafil 20 mg for the dose limits behind these rows.

Are the side effects different on daily tadalafil?

The once-daily doses (2.5 mg or 5 mg) have their own tables. In three 12-week placebo-controlled trials (mean age 58), 6% of men on 5 mg reported headache and 5% dyspepsia, versus 5% and 2% on placebo, and 3% reported flushing versus 1%. The discontinuation rate was 4.1% versus 2.8% on placebo.¹ In the label's prostate trials (mean age 63), headache was reported by 4.1% on 5 mg versus 2.3% on placebo, dyspepsia 2.4% versus 0.2%, and back pain 2.4% versus 1.4%.¹ Our article on tadalafil 5 mg covers that schedule.

Why does tadalafil cause headaches, and how long do they last?

Headache is the most common tadalafil side effect in the Cialis label, and it is dose-related: 15% of men on 20 mg, 11% on 10 mg and 5% on placebo in as-needed ED trials.¹ Taken every day, the rates are lower: 3% on 2.5 mg and 6% on 5 mg, against 5% on placebo, in the label's once-daily ED trials, and 4.1% on 5 mg against 2.3% on placebo in its prostate trials.¹ The label does not explain why headache happens, so any mechanism offered elsewhere is not from this source.

On timing, the patient information says the common side effects, headache included, usually go away after a few hours. That is different from tadalafil back pain, which the label places 12 to 24 hours after a dose.¹ Headache was also among the reactions that led at least two men in the prostate trials to stop the drug, so it can be bothersome enough to matter.¹ Alcohol can add to it: the label says drinking too much with tadalafil can raise the chance of a headache or dizziness.¹ A headache that is severe, sudden or comes with vision or hearing changes is not the ordinary pattern and needs medical attention. A man troubled by routine headaches can ask the prescriber about a lower dose, as the label's dose table shows the rate falls with dose.

Why does tadalafil cause back pain and muscle aches?

The label does not give a mechanism, but it describes the pattern. Back pain or myalgia generally occurred 12 to 24 hours after dosing in pharmacology trials and typically resolved within 48 hours. It was characterized by diffuse lower back, buttock, thigh or trunk muscle discomfort that was worse lying down, was usually mild or moderate, and resolved without medical treatment.¹ This delayed onset is a useful clue: a man who feels it the day after a dose may link it to tadalafil.

What serious side effects can tadalafil cause?

The label lists several warnings that are uncommon but need action.¹

• Prolonged erection and priapism. Rare reports of erections lasting more than 4 hours and priapism (painful erections over 6 hours). An erection beyond 4 hours, painful or not, needs emergency medical attention, because priapism can cause irreversible damage to erectile tissue.¹
• Sudden vision loss. Stop the drug and seek care if vision suddenly drops in one or both eyes; it may be non-arteritic anterior ischemic optic neuropathy (NAION). The label states that neither the rare reports nor the observational studies establish that PDE5 inhibitors cause NAION.¹
• Sudden hearing loss. Reported, sometimes with tinnitus and dizziness, in temporal association with PDE5 inhibitors; the label says it cannot determine whether the drug is the cause.¹
• Low blood pressure and fainting. Possible with alpha-blockers and other blood pressure medicines, and with heavy alcohol use.¹
• Heart events. Heart attack, sudden cardiac death, stroke and chest pain have been reported after marketing in men, most of whom had existing cardiovascular risk factors. The label says it is not possible to tell whether the drug, sexual activity or the underlying disease caused them.¹

Does tadalafil raise the risk of NAION?

The evidence is mixed and observational. The label cites an annual NAION incidence of 2.5 to 11.8 cases per 100,000 men aged 50 or older and two case-crossover studies for the PDE5 inhibitor class, with risk estimates of 2.15 (95% CI 1.06 to 4.34) and 2.27 (95% CI 0.99 to 5.20).¹ A 2018 meta-analysis of five observational studies found no significant higher risk of NAION within a month of use for PDE5 inhibitors overall (RR 1.16, 95% CI 0.98 to 1.39), although the subgroup for tadalafil had RR 2.14 (95% CI 1.20 to 3.84) and sildenafil 2.25. The authors called for caution because confounders could not be controlled and NAION is rare and hard to diagnose.² NAION risk is higher in men with a crowded optic disc, age over 50, diabetes, hypertension, heart disease, high cholesterol and smoking, and men who have already had NAION in one eye are at increased risk of recurrence.¹ A man with any of these should raise them with his prescriber.

Who should not take tadalafil?

Tadalafil is contraindicated with any form of organic nitrate, regularly or intermittently, and with guanylate cyclase stimulators such as riociguat.¹ If nitrate treatment becomes medically necessary for a life-threatening situation, the label says at least 48 hours should have passed since the last dose.¹ Hypersensitivity reactions, including Stevens-Johnson syndrome, have been reported and are a contraindication in men with a known serious allergy to tadalafil.¹ The label says men with a recent heart attack (within 90 days), unstable angina or angina during sex, among other groups, were not studied and tadalafil is not recommended for them. Our guides to ED medication interactions and ED and heart health cover those cases.

Is long-term tadalafil safe?

The label says that in once-daily trials 1,434 men were treated for at least 6 months, 905 for at least 1 year and 115 for at least 2 years.¹ A post-marketing randomized open-label trial in China followed 635 men on 2.5 mg or 5 mg daily; 580 continued 5 mg for 21 more months. Adverse events at 12 and 24 months were similar, the most common being upper respiratory tract infection and headache, and the authors reported a favorable safety profile over two years.³ This was open-label with no control group, so it describes tolerability rather than comparing risk. The label also notes that adverse events from the trials do not capture every effect seen in practice, because postmarketing reports come from a population of uncertain size.¹

How should a man handle side effects?

The label's guidance is mostly about when to seek care. Seek emergency help for an erection lasting more than 4 hours, stop and call for sudden vision or hearing loss, and tell the prescriber about chest pain, fainting or dizziness.¹ For milder effects such as headache or indigestion, the label's tables show rates rise with dose, so a lower dose is something to ask about rather than stopping the drug alone. Because the Cialis label lets prescribers adjust the dose between 5 mg and 20 mg as needed, side effects are a reason to talk about the dose, not just a verdict on the drug.¹ Alcohol deserves its own caution: the label says substantial consumption (for example 5 units or more) with tadalafil can increase dizziness, headache and a fall in standing blood pressure.¹

Questions readers ask

What are the most common side effects of tadalafil?

Headache, indigestion, back pain, muscle aches, nasal congestion and flushing. In the label's as-needed trials, headache was reported by 11% to 15% of men on 10 or 20 mg versus 5% on placebo.

How long does a tadalafil headache last?

The Cialis patient information says the common side effects, including headache, usually go away after a few hours. Back pain and muscle aches are different and generally begin 12 to 24 hours after a dose.

How long do tadalafil side effects last?

The label says back pain or muscle aches generally begin 12 to 24 hours after dosing and typically resolve within 48 hours. It does not give one duration for other effects.

Can tadalafil cause vision or hearing loss?

Rarely. The label reports sudden vision loss (possibly NAION) and sudden hearing loss in temporal association with PDE5 inhibitors, and says a causal link is not established. Stop the drug and seek medical help right away.

Are there side effects from taking tadalafil every day?

Daily 5 mg users reported headache (6% vs 5% placebo), dyspepsia (5% vs 2%) and flushing (3% vs 1%) in 12-week trials, and a 2-year open-label trial found adverse events at 12 and 24 months were similar.

Does alcohol make tadalafil side effects worse?

The label says substantial alcohol consumption, for example 5 units or more, with tadalafil can increase dizziness, headache and a fall in standing blood pressure.

Further reading

Part of our guide: How ED Medications Work: Timing, Food, Interactions and Combinations

• Sildenafil Headache: How Common Is It?
• Tadalafil With Alcohol: How Much Is Too Much?
• What Is Tadalafil Used For? The Three Approved Uses
• Tadalafil Brand Names: Which Brand Is Used for What