What are the side effects of Cialis (tadalafil) when used for erectile dysfunction?

Medical Advisory BoardAll articles are reviewed for accuracy by our Medical Advisory Board
Educational purpose only • Exercise caution as content is pending human review
Article Review Status
Submitted
Under Review
Approved

Last updated: September 18, 2026 • View editorial policy

Have a follow-up question?

Our Medical A.I. is used by practicing medical doctors at top research institutions around the world. Ask any follow up question and get world-class guideline-backed answers instantly.

Ask Question

Cialis Side Effects for Erectile Dysfunction

The most common side effects of Cialis (tadalafil) for erectile dysfunction are headache, dyspepsia (indigestion), back pain, nasal congestion, flushing, and myalgia (muscle pain), with most adverse events being mild to moderate and dose-dependent. 1, 2

Common Side Effects by Frequency

Based on FDA labeling and clinical guideline data, the following adverse reactions occur in men using tadalafil for ED:

Most Frequent Side Effects (≥2% incidence):

  • Headache: 11-15% (dose-dependent: 5 mg = 11%, 20 mg = 15%)
  • Dyspepsia: 8-10% (increases with higher doses)
  • Back pain: 5-6%
  • Myalgia (muscle pain): 3-4%
  • Nasal congestion: 3%
  • Flushing: 3% (notably lowest among all PDE5 inhibitors)
  • Pain in limbs: 3%

2

Once-Daily Dosing Side Effects (2.5-5 mg):

When using tadalafil daily for ED, the side effect profile is similar but with slightly different frequencies:

  • Headache: 3-6%
  • Dyspepsia: 4-5%
  • Back pain: 3%
  • Nasopharyngitis: 3-4%
  • Upper respiratory tract infection: 3%

2

Important Characteristics of Side Effects

Back Pain and Myalgia Pattern

A distinctive feature of tadalafil is the timing and nature of back pain/myalgia, which typically:

  • Occurs 12-24 hours after dosing
  • Resolves within 48 hours
  • Presents as diffuse bilateral lower lumbar, gluteal, thigh, or thoracolumbar discomfort
  • Worsens when lying down
  • Is generally mild to moderate (severe in <5% of cases)
  • Responds well to acetaminophen or NSAIDs
  • Leads to discontinuation in only ~0.5% of patients

2

Dose-Response Relationship

Most adverse events follow a clear dose-response pattern: men taking higher doses (20 mg) experience statistically higher rates of side effects compared to lower doses (10 mg or 5 mg) and placebo. 1

Less Common but Notable Side Effects (<2%)

Additional adverse reactions reported in controlled trials include:

  • Dizziness
  • Visual disturbances (color vision changes are rare, <0.1%)
  • Palpitations
  • Nausea
  • Gastroesophageal reflux
  • Muscle spasm
  • Diarrhea

2

Special Populations and Precautions

Age-Related Considerations

In men ≥65 years of age, diarrhea was reported more frequently (2.5%) compared to younger patients. 2

Hepatic and Renal Impairment

  • Mild to moderate impairment: Use with caution, start with lower doses due to delayed metabolism
  • Severe renal or liver disease: Generally not recommended

1

Discontinuation Rates

The overall discontinuation rate due to adverse events is low: 3.6-4.1% with tadalafil versus 1.6-2.8% with placebo across clinical trials. The most common reasons for discontinuation include headache, upper abdominal pain, and myalgia. 2

Comparative Advantage

Tadalafil has the lowest rate of flushing among all PDE5 inhibitors, making it a preferred option for men particularly bothered by this side effect. 1

Clinical Pitfalls to Avoid

  1. Don't assume treatment failure after one dose: Many side effects are transient and diminish with continued use
  2. Educate patients about back pain timing: This predictable pattern (12-24 hours post-dose, resolving in 48 hours) helps distinguish it from other causes
  3. Titrate the dose: Work with patients to find the optimal balance between efficacy and tolerability—starting lower and adjusting upward as needed
  4. Consider once-daily dosing: The 2.5-5 mg daily regimen has a more favorable side effect profile for some patients compared to higher on-demand dosing

1, 2

References

1
Guideline

erectile dysfunction: aua guideline.

The Journal of urology, 2018

Related Questions

After taking a first 5 mg dose of tadalafil at 4 p.m., the patient experienced a mild throbbing headache and ear flushing 30 minutes later; how long are these side effects expected to last?
Does tadalafil cause dependence (physical or psychological)?
What is the optimal timing for taking Cialis (tadalafil)?
Can tadalafil cause severe headache during sexual activity?
Can a patient take tadalafil 5 mg daily and also take an additional dose on an as‑needed (prn) basis?
What is the appropriate management for a 5 cm benign thyroid nodule confirmed by fine‑needle aspiration?
For a taper regimen of 10‑mg tablets—3 tablets daily for 5 days, then 2 tablets daily for 5 days, then 1 tablet daily for 5 days, followed by 0.5 tablet daily thereafter—how many tablets should be sent?
In which situations is a CT thorax indicated for pneumothorax?
What is the appropriate initial evaluation and management for a 40‑year‑old woman with hypothyroidism on levothyroxine who has had multiple episodes of dizziness, a fainting spell in the past week, right‑ear tinnitus, and morning‑predominant vertigo?
In a male patient with a free testosterone of 2.7 pg/mL and a total testosterone of 392 ng/dL, what does this indicate and what are the recommended next steps?
Are there any contraindications or timing guidelines for taking Slynd (drospirenone/ethinyl estradiol) oral contraceptive, Nurtec (rimegepant), triptans (almotriptan, frovatriptan, zolmitriptan), or dihydroergotamine nasal spray with ketamine, especially regarding hypertension?

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.