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Key facts at a glance
- Definition
- A prolonged, uncontrolled erection beyond or unrelated to sexual stimulation · Cialis (tadalafil) labelAUA/SMSNA guideline · PubMed; Cialis (tadalafil) label
- When to act
- Over 4 hours, “whether painful or not”: seek emergency careCialis (tadalafil) label · DailyMed
- Why it’s urgent
- Untreated priapism risks tissue damage and permanent loss of potencyViagra (sildenafil) label · DailyMed
- Self-treatment
- Do not self-treat; seek emergency help · Cialis (tadalafil) labelCleveland Clinic
- Compounded status
- The Mendoxa compounded tablet is not FDA-approvedFDA compounding Q&A
Erection lasting 4 hours or more? What to do right now
Have an erection lasting 4 hours or more right now? Go to the nearest ER or call 911. Do not wait for an online visit; the Cialis (tadalafil) label directs patients to emergency care even without pain, and MedlinePlus says to get to the hospital ER right away.
- Get emergency care. Do not wait for pain to start or for the erection to fade (Cialis (tadalafil) label).
- Do not try home remedies. Cleveland Clinic advises against self-treatment; the Viagra (sildenafil) label warns that delayed treatment can permanently damage penile tissue.
- Tell the emergency team what you took and when. Bring your medicine list and mention any injury or blood disorder; MedlinePlus describes a history and examination, and the Viagra (sildenafil) label names sickle cell anemia, leukemia and multiple myeloma as conditions requiring caution.
Here to understand the warning before starting ED treatment? Use the guide below, then start a Mendoxa online visit for a provider assessment. Prescription required · Independent licensed providers.
Priapism meaning: what is priapism?
Priapism describes an erection that persists beyond sexual stimulation or happens without it. The AUA/SMSNA guideline (2022) describes it as prolonged and uncontrolled; the Cialis (tadalafil) label gives the emergency action threshold of more than 4 hours.
The action threshold is not a countdown to safety. At 4 hours, seek emergency care; lack of pain does not make waiting safe (Cialis (tadalafil) label). MedlinePlus also advises immediate care for an erection that does not go away.
For medication background, read our sildenafil guide and tadalafil guide; the warnings below come from the Viagra (sildenafil) label and Cialis (tadalafil) label.
Ischemic vs non-ischemic vs stuttering priapism
The type determines treatment, but symptoms alone are not enough to choose your care. Cleveland Clinic describes clinical tests to distinguish the types; follow the Cialis (tadalafil) label emergency warning even if the erection is painless.
| Type | What it is | Pain | Urgency | Typical causes named by the source |
|---|---|---|---|---|
| Ischemic (low-flow) | Blood is trapped in the erectile chambers, with little or no blood flow (AUA/SMSNA guideline); the most common type | Painful; pain typically worsens over time (Cleveland Clinic) | Emergency. The AUA/SMSNA guideline calls acute ischemic priapism an emergency; it “doesn’t go away without treatment” (Cleveland Clinic) | Medicines, including ED drugs; sickle cell disease and other blood disorders; recreational drugs; often no cause found (Cleveland Clinic; Cigna (Healthwise)); emergency warning: Cialis (tadalafil) label |
| Non-ischemic (high-flow) | A persistent erection caused by uncontrolled arterial blood flow (AUA/SMSNA guideline) | Usually painless (AUA/SMSNA guideline) | After a clinician confirms the type, urgency differs from ischemic disease; do not diagnose it yourself (Cleveland Clinic) | Injury to the penis or perineum; the guideline highlights straddle injuries (Cleveland Clinic; AUA/SMSNA guideline); emergency warning: Cialis (tadalafil) label |
| Stuttering (recurrent ischemic) | Unwanted painful erections recur with periods in between when the erection goes down (AUA/SMSNA guideline) | Painful episodes (AUA/SMSNA guideline) | Any episode that does not go down is treated like ischemic priapism; recurring episodes need follow-up with a urologist (Cleveland Clinic) | Associated with sickle cell disease (AUA/SMSNA guideline); emergency warning: Cialis (tadalafil) label |
Sources: AUA/SMSNA guideline 2022; Cleveland Clinic; Cigna Healthwise. Accessed Oct 28, 2026.
Emergency warning applies across this table: see the Cialis (tadalafil) label. Accessed Oct 28, 2026.
What ED drug labels say about priapism
Both labels tell patients to seek help after 4 hours. These are the exact action sentences in section 5.2 of the Viagra (sildenafil) label and section 5.3 of the Cialis (tadalafil) label, checked Oct 28, 2026.
| Label (DailyMed) | Exact warning text | Conditions named for caution |
|---|---|---|
| Viagra (sildenafil) · section 5.2 | “In the event of an erection that persists longer than 4 hours, the patient should seek immediate medical assistance.” (Viagra (sildenafil) label) | Sickle cell anemia, multiple myeloma, leukemia; anatomical deformation of the penis such as Peyronie’s disease (Viagra (sildenafil) label) |
| Cialis (tadalafil) · section 5.3 | “Patients who have an erection lasting greater than 4 hours, whether painful or not, should seek emergency medical attention.” (Cialis (tadalafil) label) | Sickle cell anemia, multiple myeloma, leukemia; anatomical deformation of the penis (Cialis (tadalafil) label) |
Sources: Viagra (sildenafil) label (revision 12/2017); Cialis (tadalafil) label (revision 03/2026). Accessed Oct 28, 2026.
The labels also use a 6-hour description of painful priapism; that wording does not change their earlier 4-hour instruction to seek help (Viagra (sildenafil) label; Cialis (tadalafil) label). For another medication-safety question, see how much Viagra is too much?
What causes priapism?
Possible causes include medicines, blood disorders and injury; sometimes the cause is unknown. The Viagra (sildenafil) label and Cialis (tadalafil) label warn about prolonged erections and name conditions that predispose patients to priapism.
- ED medicines: prolonged erections have been reported with sildenafil and with the drug class that includes tadalafil (Viagra (sildenafil) label; Cialis (tadalafil) label).
- Blood disorders: sickle cell disease, leukemia and multiple myeloma are among the conditions named for caution (Viagra (sildenafil) label; Cialis (tadalafil) label).
- Injury: penile or perineal injury can cause high-flow priapism (Cleveland Clinic; emergency guidance: Cialis (tadalafil) label).
- Other medicines and substances: Cleveland Clinic lists certain antidepressants, antipsychotics and recreational drugs; the Viagra (sildenafil) label reinforces why a complete medical history matters before ED prescribing.
For related reading, see ED injections and Viagra side effects; for the prolonged-erection warning, use the Viagra (sildenafil) label.
Why priapism treatment is time-sensitive
Prompt treatment helps protect future erectile function. The Viagra (sildenafil) label warns that untreated priapism can damage penile tissue and cause permanent loss of potency; the Cialis (tadalafil) label warns of irreversible erectile-tissue damage.
The AUA/SMSNA guideline (2022) describes the condition as time-dependent and progressive. The emergency instruction is already at more than 4 hours in the Cialis (tadalafil) label; there is no reason to wait for a later damage threshold.
What each path includes
Choose emergency care for a current prolonged erection; choose a provider visit for future ED care. The Cialis (tadalafil) label emergency warning comes first.
| Your situation | Starting point | What it includes |
|---|---|---|
| Erection lasting 4+ hours now, or painful and not going down | Call 911 or go to the nearest emergency room | Urgent assessment of the type and treatment by emergency clinicians (Viagra (sildenafil) label; Cialis (tadalafil) label; MedlinePlus) |
| Repeated unwanted erections that go down on their own | Your doctor or a urologist | Review of recurrent symptoms and possible causes (AUA/SMSNA guideline; Cleveland Clinic) |
| You take ED medicine and had a prolonged erection before | The prescriber who manages your ED treatment | History, medicine review and whether the treatment still fits; the labels list priapism-prone conditions (Viagra (sildenafil) label; Cialis (tadalafil) label) |
| You want ED treatment with medical oversight | Mendoxa online visit | Independent licensed providers review history and medicines; Prescription required; the compounded tablet is not FDA-approved |
Sources: Viagra (sildenafil) label; Cialis (tadalafil) label; Cleveland Clinic; AUA/SMSNA guideline (2022); MedlinePlus. Accessed Oct 28, 2026.
Before any ED visit, compare ED medication options, list your current medicines and mention any past prolonged erection.
Could Mendoxa ED care fit you?
Online ED visit · Prescription required · Independent licensed providers · Not available in California
Safety checks before ED medication
- Sildenafil and tadalafil are contraindicated with organic nitrates or riociguat (Viagra (sildenafil) label; Cialis (tadalafil) label).
- An erection lasting more than 4 hours needs immediate medical care (Viagra (sildenafil) label; Cialis (tadalafil) label).
- Stop and seek care for sudden vision loss or sudden decrease or loss of hearing (Viagra (sildenafil) label; Cialis (tadalafil) label).
- Common adverse effects include headache and flushing with sildenafil, and headache, indigestion and back pain with tadalafil (Viagra (sildenafil) label; Cialis (tadalafil) label).
- The APOKYN (apomorphine) label contraindicates use with 5HT3 antagonists such as ondansetron and warns about nausea and fainting.
Do not combine ED medicines on your own or take more than prescribed. The Viagra (sildenafil) label and Cialis (tadalafil) label say combinations with other PDE5 inhibitors or ED therapies have not been studied and advise against such use. See ED medication and nitrates.
Before your next ED prescription: review your history and medicines
Use ED medication with a licensed provider who reviews your history and dose. That review covers conditions the Viagra (sildenafil) label and Cialis (tadalafil) label flag for priapism, such as sickle cell anemia, leukemia and multiple myeloma. It also covers nitrates and other medicines. Prescription required.
With Mendoxa, Independent licensed providers assess whether the compounded rapid-dissolve tablet fits you. The tablet contains sildenafil, tadalafil and apomorphine and is not FDA-approved. Ingredient references are the Viagra (sildenafil) label, Cialis (tadalafil) label and APOKYN (apomorphine) label. APOKYN is a Parkinson’s injection, and its label does not approve this ED combination.
Start the Mendoxa online visit to ask whether ED treatment fits your medical history. Read the combination ED tablet guide for product context. Prescription required · Independent licensed providers.
Mendoxa ED plans and prices
The Mendoxa ED tablet is a compounded rapid-dissolve tablet with sildenafil (the active ingredient in Viagra), tadalafil (the active ingredient in Cialis) and apomorphine (APOKYN label). It dissolves under the tongue. A licensed clinician decides if it fits you and selects the strength. Compounded medicines are not FDA-approved.
| Tablets per month | 1-month total | Per tablet (1 month) | 3-month total | Per tablet (3 months) |
|---|---|---|---|---|
| 6 tablets / month | $129 | $21.50 | $329 | $18.28 |
| 10 tablets / month | $149 | $14.90 | $379 | $12.63 |
| 20 tablets / month | $179 | $8.95 | $449 | $7.48 |
The 3-month total covers three months at the monthly tablet quantity shown.
If prescribed · Cancel anytime · Available in 49 states (not California). Prices from the Mendoxa intake at try.mendoxa.co/f/ed on Oct 28, 2026. The intake always shows the current price.
FAQ
What is priapism?
Priapism is a prolonged, uncontrolled erection that persists beyond sexual stimulation or occurs without it (AUA/SMSNA guideline (2022)). Seek emergency care at 4 hours; the Cialis (tadalafil) label says to get help after 4 hours whether painful or not.
How long is too long for an erection?
At 4 hours, go to the ER or call 911. The Viagra (sildenafil) label and Cialis (tadalafil) label say an erection lasting longer than 4 hours needs immediate medical attention; do not wait for pain.
Will priapism go away on its own?
Do not wait to find out. Cleveland Clinic says ischemic priapism does not resolve without treatment; the Cialis (tadalafil) label says to seek emergency attention after 4 hours, even without pain.
Can Viagra or Cialis cause priapism?
Yes, rarely. The Viagra (sildenafil) label reports it infrequently and the Cialis (tadalafil) label calls it rare. Both labels say to get emergency help for an erection lasting more than 4 hours.
Can priapism cause permanent erectile dysfunction?
Yes. The Viagra (sildenafil) label warns of permanent loss of potency and the Cialis (tadalafil) label warns of irreversible erectile-tissue damage if treatment is delayed.
How is priapism treated?
Treatment depends on the type and the cause. MedlinePlus says medicines or a procedure may be needed; the Cialis (tadalafil) label says an erection longer than 4 hours needs emergency medical attention. Do not try to treat it yourself.
Ready to see if the Mendoxa ED tablet fits you?
From $129/month if prescribed · Cancel anytime · Available in 49 states (not California)
How we wrote this
Written by the Mendoxa editorial team · Sources: DailyMed/FDA. Medical facts on this page come from the FDA-approved labels on DailyMed and Drugs@FDA; each drug name links to its label. We checked the linked DailyMed warnings, FDA compounding information and MedlinePlus emergency advice on Oct 28, 2026, and checked the 2022 guideline citation and definition through AUA/SMSNA guideline (2022). The Viagra (sildenafil) label and Cialis (tadalafil) label action sentences are quoted verbatim. The types table summarizes the guideline and Cleveland Clinic. Ingredient labels describe separate products and do not establish approval of a compounded combination.
Updated Oct 28, 2026. This page is general information, not medical advice. A licensed clinician decides what fits you.
References
- DailyMed: VIAGRA (sildenafil citrate) tablet, film coated, label revised 12/2017. Accessed Oct 28, 2026.
- DailyMed: CIALIS (tadalafil) tablet, film coated, label revised 3/2026. Accessed Oct 28, 2026.
- DailyMed: APOKYN (apomorphine hydrochloride) injection, label revised 6/2022. Accessed Oct 28, 2026.
- FDA (Drugs@FDA): VIAGRA (sildenafil) prescribing information, NDA 020895. Accessed Oct 28, 2026.
- FDA (Drugs@FDA): CIALIS (tadalafil) prescribing information, NDA 021368. Accessed Oct 28, 2026.
- FDA: Compounding and the FDA, questions and answers. Accessed Oct 28, 2026.
- AUA/SMSNA guideline (2022). Bivalacqua TJ, Allen BK, Brock GB, et al. J Urol. 2022;208(1):43–52. Accessed Oct 28, 2026.
- Cleveland Clinic: Priapism. Accessed Oct 28, 2026.
- MedlinePlus: Penis pain. Accessed Oct 28, 2026.
- Mendoxa ED care (product, format, max 1 dose per 24 hours). Accessed Oct 28, 2026.
- Mendoxa ED intake: plan prices (term_options). Accessed Oct 28, 2026.
About Mendoxa
Mendoxa (mendoxa.co) is a US telehealth brand. Independent licensed providers (licensed clinicians in the LocumTele network) review each online visit, and prescriptions are filled by Rush Pharmacy, a licensed US pharmacy. Available in 49 states (not California).
- Prescription required. A licensed clinician reviews every visit and can say no. A prescription is not automatic.
- A compounded medicine is not an FDA-approved finished product (FDA compounding Q&A).
- Plans: 1 month or 3 months, from $129. If prescribed · Cancel anytime · Available in 49 states (not California).
Compounded medication prescribed only if a licensed U.S. clinician decides it is appropriate. Not FDA-approved as a finished product. Not available in California. This site is not for emergencies. Call 911 if you need urgent care.