Can I just start sildenafil 50 mg tonight and do bloods later if it works?
History, then the medicine list
History items that change the next test
- What fails: get, keep, or both.
- Morning or nocturnal erections still present or not.
- Onset sudden after a new tablet, or slow over years.
- Chest pain, claudication, smoking, known diabetes or lipids.
- Prostate surgery, pelvic radiation, Peyronie plaque, trauma.
- Mood, alcohol, and whether a partner is in the room for the history.
AUA statement 1 is a clinical principle. Men with ED need a thorough medical, sexual, and psychosocial history, a physical examination, and selective laboratory testing.
Define the complaint. Failure to get rigid is not premature ejaculation and not low desire, though those can travel with it. Chronology, morning erections, and partner context belong in the first visit.
Arterial inflow trouble often needs more stimulation and still builds slowly. Venous leak often builds and then empties. Those patterns are clues, not imaging orders on day one.
The medicine list is part of the history, not an afterthought. Thiazides, some beta-blockers, spironolactone, 5-alpha-reductase inhibitors, SSRIs, and heavy alcohol use can explain a new failure.
Recreational nitrates close every PDE5 path before the visit ends. Ask about poppers by that name. Men often leave them off a 'prescription list'.
Pelvic or perineal trauma, including some cycling and straddle injuries, can stenose a penile artery. That history is easy to skip if the visit starts with a brand.
Validated scores such as SHIM (the short IIEF) grade severity and later track a tablet. They do not replace the interview. AUA recommends them as expert opinion, not as a standalone diagnosis.
Psychosocial strain, performance fear, and a relationship stall are real mechanisms. They still sit after the vascular and drug screen, because missing a nitrate or a silent diabetes is the costlier miss.
How the erection is built, and where it breaks
Sexual stimulation releases nitric oxide in the penis. Guanylate cyclase then raises cGMP. Smooth muscle relaxes. Arterial inflow fills the corpora. Veins are compressed against the tunica.
PDE5 breaks down that cGMP. A PDE5 tablet only helps if nitric oxide was released and the vessels can still dilate. No desire, no nerve signal, no inflow: the tablet has nothing to protect.
Vascular failure is the common adult story: hypertension, diabetes, lipids, smoking, and age on the same endothelium. The penis can advertise that years before a coronary event.
Neurogenic failure follows prostatectomy, pelvic radiation, spinal disease, or neuropathy. Rates after nerve-sparing surgery still drop. A tablet can help some of those men. It cannot regrow a cut cavernous nerve.
Hormonal failure is the low-T subset, and only when the morning total is low with signs. Psychogenic failure is situational, often with spared morning rigidity. Drug failure is the list already taken.
Peyronie plaque and penile trauma are local mechanical breaks. They need an exam, not a larger PDE5 strength as first move.
A focused exam looks at the abdomen, penis, testes, hair, breasts, and lower-limb pulses. Genital sensation and a cremasteric reflex speak to the sacral arc. That is still work-up, not a tablet.
AUA wants the clinician to start the sexual question. Many men will not. Waiting for them to name a brand first is how the glucose draw never happens.
Up to about 30 million men in the United States are cited in the AUA epidemiology note. Prevalence is not a reason to skip the individual medicine list.
Specialized vascular testing stays selected. A first visit that ends with glucose, lipids, morning T, and a nitrate answer has already done the high-yield work.
If the first tablet fails
A failed tablet is often a failed trial: late swallow, fatty meal on sildenafil, no stimulation, one lonely attempt, or a daily tadalafil judged before day 5.
Check the schedule against the right note. Sildenafil 50 mg timing for the hour and the meal. 2.5 mg versus 10 mg for the plateau.
Then look again at the work-up. Uncontrolled glucose, an SSRI, or an untreated depression will beat a perfect 50 mg swallow.
Referral to a mental-health clinician is an AUA moderate recommendation when adherence, anxiety, or the relationship is the block. That is treatment, not a brush-off.
Second-line tools after a real oral trial include intraurethral or injection alprostadil, a vacuum erection device, and a penile prosthesis. Those need a urology conversation, not a second anonymous tablet from a search ad.
Yohimbine and assorted 'male' supplements have inconsistent trials in the student curriculum. They are not a substitute for glucose, lipids, and a morning T.
If the man is high Princeton risk, a failed tablet is the wrong puzzle. Fitness for sex was the first unanswered item. Send that back to cardiology.
A vacuum device can be a first choice under AUA's shared-decision model. Invasiveness is not a mandatory ladder. Honesty about nitrates still is.
When a PDE5 tablet is even allowed
After history, exam, labs, and a nitrate-and-risk screen, an oral PDE5 inhibitor is a usual first treatment if the man wants a tablet and sex is allowed.
AUA's framework does not force a ladder of invasiveness. Some men will still start with a tablet. Some will choose a vacuum device or an implant first. Shared decision is the stated model.
If the pick is a tablet, duration and food decide the INN. Tadalafil for a 36-hour window or a 2.5 mg daily start. Sildenafil 50 mg for a short, meal-sensitive evening. Vardenafil 20 mg only after the QT list is clean.
Lifestyle is not a moral encore. Stopping smoking, cutting weight, and moving more can shift function and cut the same vascular risk the erection already flagged.
AUA also allows a man to decline treatment. The work-up still matters, because the heart risk does not decline with the tablet.
Partner sexual function belongs in the history when a partner is present. A tablet cannot fix a relationship that has already left the room.
Testosterone, when truly low with symptoms, may help desire more than rigidity. Many of those men still need a PDE5 tablet for the erection itself.
The heart sits in the same room
AUA tells clinicians to counsel that ED is a risk marker for cardiovascular disease and other conditions that may need treatment. It is a marker, not a cute sexual footnote.
Penile arteries are smaller than coronary arteries. Endothelial failure can show up in the bedroom before a stress test is ordered. Symptoms of ED may precede a cardiovascular event by as much as five years in cited series.
The Prostate Cancer Prevention Trial analysis, as used by AUA, put new ED in the same predictor class as smoking or a family history of myocardial infarction for later cardiac events. That is why the visit is not only about rigidity.
Princeton risk bands still sort fitness for sex. High risk includes unstable or refractory angina, uncontrolled hypertension, and NYHA III or IV heart failure. It also includes MI or stroke in the past 2 weeks, a high-risk arrhythmia, obstructive cardiomyopathy, and moderate-to-severe valve disease. Those men do not get a PDE5 tablet until the cardiac state is stable.
Low-risk men (controlled pressure, mild stable angina, successful revascularization, and similar) can discuss first-line tablets if nitrates are absent. Intermediate risk needs a cardiology look first.
A man who cannot walk a flight without chest tightness is not a sildenafil-timing problem. He is a cardiology problem who also cannot have sex safely.
Glucose, lipids, morning testosterone
| Step | What it answers | Source posture |
|---|---|---|
| History and exam | Drug, nerve, plaque, pulses, breasts, testes | AUA clinical principle |
| Glucose or A1c | Diabetes as a shared vascular hit | Selected lab |
| Lipids | Dyslipidemia on the same arteries | Selected lab |
| Morning total T | Hypogonadism if T <300 ng/dL plus signs | AUA moderate / grade C |
| SHIM or IIEF | Severity and later tablet effect | Expert opinion |
| PDE5 tablet | Only after nitrates and cardiac risk are clear | Treatment, not step one |
AUA says that except for testosterone, glucose or A1c, and sometimes lipids, few routine blood tests change ED management. Those few still belong on the first pass.
Morning serum total testosterone should be measured in men with ED (moderate recommendation, evidence grade C). AUA defines testosterone deficiency as total T under 300 ng/dL plus symptoms and signs.
Low T can sit under low desire and under some erection failures. Replacing T in a man with a normal level is not an ED treatment. That is an AUA line worth keeping.
Fasting glucose or hemoglobin A1c and a lipid panel look for diabetes and dyslipidemia that share the same arteries. Treating those is not optional background. It is part of why the erection failed.
Creatinine, a blood count, and urinalysis are reasonable when recent values are missing. They are not a treasure hunt. They catch the comorbidities the history already hinted at.
Special tests (duplex, injection office testing, overnight rigidity) are for selected men, not a default. AUA leaves that as expert opinion when the first-line path is unclear.
The order that keeps the visit honest
Name the failure. Take the history and the medicine list. Examine. Draw glucose or A1c, lipids, and a morning testosterone. Sort cardiac risk. Only then pick a tablet, if a tablet is allowed.
Nitrates remain a hard ban on all three oral PDE5 drugs. Duration and QT are later splits, written in the comparison.
AUA's ED guideline and the student curriculum page are the work-up spine. A clinician who can see the man still has to run it. This note is the order, not the clinic visit.
If a tablet is later allowed, duration lives in the 36-hour versus 4-hour comparison. The 50 mg clock lives in the sildenafil timing note. Neither page replaces this order.
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What readers asked
Answered by Dr. Elena Marchetti, MD · Infectious diseases & clinical pharmacology
These replies stay on why an erection fails and which work-up comes first. A tablet brand is out of order until that list is done.
You can swallow a tablet. You should not treat that as the work-up. AUA puts history, exam, and selected labs in front because ED is a cardiovascular risk marker, not a lifestyle inconvenience. A tablet that 'works' can hide diabetes, a crashing lipid panel, or a nitrate you have not mentioned. Morning testosterone is a moderate AUA recommendation in men with ED, not a souvenir test for later. If a nitrate spray is in the house, 50 mg tonight is contraindicated, success or not. If walking brings chest pressure, Princeton high-risk rules say sex itself waits. I would rather delay one evening and draw glucose or A1c, lipids, and a morning T than celebrate a lucky tablet and miss a five-year warning. Bring the full medicine list, including drops and 'just in case' sprays. Then, if sex is allowed and nitrates are absent, 50 mg with a real hour and a light meal is a fair first trial. The order is the safety.
His mornings are still firm. Does that mean we skip the heart talk?
Morning erections argue against a complete end-organ shutdown. They do not clear the arteries. Psychogenic load, an SSRI, and situational fear can spare nocturnal rigidity and still wreck partnered sex. Vascular ED can also be partial. AUA still wants the history, the exam, and the selected labs. ED remains a risk marker for later cardiac events in the prevention-trial analysis they cite. Skipping lipids and glucose because mornings are firm is how a 'it's only in my head' story misses diabetes. Do the SHIM so you have a baseline. Ask about sudden versus slow onset. Ask about new tablets. If mornings vanished as well, the organic list gets heavier, not lighter. Either way, nitrates and chest symptoms still come before any PDE5 brand. Firm mornings are useful data. They are not a pass on the work-up.
The clinic wants a morning testosterone. I feel fine otherwise. Is that theatre?
It is an AUA moderate recommendation with grade C evidence, which means the panel still wants the draw even though the evidence is not a giant randomized story. Total T under 300 ng/dL plus symptoms and signs is their deficiency definition. Some men who 'feel fine' still have low desire they have stopped noticing, small testes, or anemia that only shows on the bloods. A normal T stops a useless androgen prescription, which is itself a win. A low T does not automatically fix the erection. Many hypogonadal men still need a PDE5 tablet after replacement is considered. Draw it in the morning. Repeat if the first value is low before anyone starts a gel. The testosterone is one row. Glucose or A1c and lipids are the rows that catch the shared vascular disease. Skip those and the T becomes a single souvenir. Do the set.
He had a stent six weeks ago and still uses a nitrate. Which pill is least bad?
None. Organic nitrates contraindicate tadalafil, sildenafil, and vardenafil. 'Least bad' is how people get profound hypotension. Six weeks after a stent he may or may not be low Princeton risk. That is a cardiology call about fitness for sex, separate from the tablet. If the nitrate is still required, the oral PDE5 class is closed. If the cardiologist later stops the nitrate and clears sex, then duration and QT become discussable. Until both of those are true, vacuum devices and other non-nitrate paths are the honest options, and only with the team that knows the stent. Do not buy a 'natural' PDE5 analogue online to dodge the label. The interaction is the nitric-oxide path, not the brand name. Work-up first included the cardiac history. In his case that history already answered the tablet question: no.
Treat every answer here as general teaching, not a decision made for the individual who wrote in. What is right for you turns on your history, your bloods and the rest of your medicine list — and that is a conversation for a prescriber who can see all of it at once.