Parasympathetic input allows erection by relaxation of trabecular smooth muscle and dilation of the helicine arteries of the penis. This leads to expansion of the lacunar spaces and entrapment of blood by compressing venules against the tunica albuginea, a process referred to as the corporal veno-occlusive mechanism. The tunica albuginea must have sufficient stiffness to compress the venules penetrating it so that venous outflow is blocked and sufficient tumescence and rigidity can occur.
Inside the cell, NOS catalyzes the oxidation of L-arginine to NO and L-citrulline. Endogenous blockers of this pathway have been identified. The gaseous NO that is produced acts as a neurotransmitter or paracrine messenger. Its biologic half-life is only 5 seconds. NO may act within the cell or diffuse and interact with nearby target cells. In the corpora cavernosa, NO activates guanylate cyclase, which in turn increases cyclic guanosine monophosphate (cGMP). Relaxation of vascular smooth muscles by cGMP leads to vasodilation and increased blood flow.
Inside the cell, NOS catalyzes the oxidation of L-arginine to NO and L-citrulline. Endogenous blockers of this pathway have been identified. The gaseous NO that is produced acts as a neurotransmitter or paracrine messenger. Its biologic half-life is only 5 seconds. NO may act within the cell or diffuse and interact with nearby target cells. In the corpora cavernosa, NO activates guanylate cyclase, which in turn increases cyclic guanosine monophosphate (cGMP). Relaxation of vascular smooth muscles by cGMP leads to vasodilation and increased blood flow.
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If you have unstable heart disease of any kind, heart failure or unstable, what we call angina, contraindication to using the medications. All right? So if you’re in an unstable medical state, these medications are not a good idea. Now, there are relative issues. If you may be taking a blood pressure medicine or a medicine for your prostate which dilates your blood vessel a little bit– you know, the typical ones are what we call the alpha blockers– you may have an additive effect from the medication. But for the most part, the medicines are incredibly safe.
Despite the accumulation of a substantial body of scientific information about erectile dysfunction, large segments of the public -- as well as the health professions -- remain relatively uninformed, or -- even worse -- misinformed, about much of what is known. This lack of information, added to a pervasive reluctance of physicians to deal candidly with sexual matters, has resulted in patients being denied the benefits of treatment for their sexual concerns. Although they might wish doctors would ask them questions about their sexual lives, patients, for their part, are too often inhibited from initiating such discussions themselves. Improving both public and professional knowledge about erectile dysfunction will serve to remove those barriers and will foster more open communication and more effective treatment of this condition.

#3 You’re not having enough sex. The more sex you’re having, the less likely you are to suffer from erectile issues. The American Journal of Medicine reports that men who had sex once *or more* a week were less likely to have issues getting and maintaining an erection. So, not having sex is actually one of the reasons you can’t get hard. [Read: 13 ways to have better sex and change the way you make love]

Constriction of the trabecular smooth muscle and helicine arteries induced by sympathetic innervation makes the penis flaccid, with blood pressure in the cavernosal sinuses of the penis near venous pressure. Acetylcholine is thought to decrease sympathetic tone. This may be important in a permissive sense for adequate trabecular smooth muscle relaxation and consequent effective action of other mediators in achieving sufficient inflow of blood into the lacunar spaces. When the trabecular smooth muscle relaxes and helicine arteries dilate in response to parasympathetic stimulation and decreased sympathetic tone, increased blood flow fills the cavernous spaces, increasing the pressure within these spaces so that the penis becomes erect. As the venules are compressed against the tunica albuginea, penile pressure approaches arterial pressure, causing rigidity. Once this state is achieved, arterial inflow is reduced to a level that matches venous outflow.
The drugs are worth trying, but don’t expect miracles. Everyone has heard of Viagra, but Cialis is actually more popular because it’s effective longer—24 to 36 hours instead of three to five. Erection drugs improve erections in around two-thirds of men. They don’t work for about one-third. When they work, they do not produce porn-star erections. Over time, many men need larger doses. But as dosage increases, side effects become more likely, notably, headache and nasal congestion. Finally, the drugs have no effect on arousal, so men may raise erections but don't feel particularly interested in sex. Many men feel disappointed with the drugs. Fewer than half refill their prescriptions.
Just as certain meds can make it difficult for men to have an orgasm, some can keep the flagpole from even getting raised in the first place. Anti-depressant medications like Prozac and Zoloft, anti-anxiety pills like Valium, high blood pressure medicine like Diuril, and even over-the-counter cold medicines like Sudafed and anti-heartburn pills like Zantac can inhibit erections.
Erections are more complicated than you think. Your brain, nerves, heart, blood vessels, and a whole lot of hormones have to work together perfectly or nothing happens. It’s a lot to ask, and sometimes things break down. And while ED happens to most guys at some point in their lives, erectile dysfunction isn’t something you can just ignore and hope it goes away.
It's definitely possible that your boner isn't cooperating because it's not really thrilled to be there. Maybe you're not sure about this partner, you're worried about pregnancy or STIs, you're not feeling comfortable with an unfamiliar hookup, or you typically need some other kind of stimulus to get in the mood. It's always worth checking in with yourself to see if one of these factors might be holding you back in bed, says Skyler. If you have a hunch that it's because you're doing something you don't want to do (or you're not doing something you do want to do) pay attention to that hunch.
When sexually stimulated there is a release of a chemical, nitric oxide (NO) in the blood vessels of the corpus cavernosum. The NO stimulates the production of a compound called cGMP, which causes relaxation of the smooth muscle in the blood vessels supplying the corpus cavernosum. PDE 5 is an enzyme that breaks down cGMP. By inhibiting the breakdown of cGMP by PDE5, these medications allow cGMP to build up in the penis. cGMP causes muscles in the corpora cavernosa of the penis to relax. When the muscle is relaxed, more blood can flow into the penis and fill the spaces in the penis. As the penis fills with blood, the veins in the penis are compressed, and this results a hard erection. When the effect on PDE5 decreases, the cGMP levels go down and the muscle in the penis contracts, causing less blood to flow into the penis and allowing the veins to open up and drain blood out of the penis.
You're not hard. You're about to have sex for the first time with your date, who's truly beautiful. All you want to do is present your glorious, super strong erection and let it do the talking. And yet when you look down, you're limp instead of hard. This doesn't make any sense! you think. Every element you could possibly need for an erection is here. Nudity, beauty, passion, the tantalizing thrill of boning someone for the first time, and a little bit of booze to take the edge off. What on earth is wrong and why are you so unlucky? You turn to your date. "I swear, this never happens..."
Everything you need to know about chlamydia Chlamydia is the most common STI in the United States, yet most people do not experience obvious symptoms. Chlamydia affects men and women and can harm the reproductive systems, sometimes permanently. Find out about the causes and symptoms of chlamydia, as well as what the best treatments are and how to get screened. Read now
PDE 5 inhibitors are broken down primarily by enzyme, cytochrome P450enzyme CYP3A4. Medications that decrease or increase the activity of CYP3A4 may affect levels and effectiveness of PDE 5 inhibitors. Such drugs include medications for the treatment of HIV (protease inhibitors) and the antifungal medications ketoconazole and itraconazole. Thus caution is recommended.

One thing you need to know.  When you are experiencing anxiety, you get a stress response.  You can read more about this here.  A stress response is what you automatically feel, say, if a fight broke out near you.  Your body gets ready to protect itself.  During a stress response, blood is diverted away from less important areas to help your heart beat faster.
I'd recommend the second option. In any long-term relationship, there will come a time when you flirt a little too much. Technology makes those little transgressions seem much more major because there's digital proof. (I'm guessing that you would never have flashed him in the real world. Would you?) Maybe you should just learn from your experience and save your boyfriend the drama. Understand that you made a mistake, and keep your breasts to yourself.
Phosphodiesterase inhibitors: This class of medications includes sildenafil, tadalafil, and vardenafil. They work by inhibiting an enzyme called phosphodiesterase type 5 (PDE-5), allowing more blood to enter the penis and helping to produce an erection. These medications are often taken before sex and will cause an erection only when the man is sexually stimulated.
Tadalafil should not be used with alpha-blockers (except Flomax), medicines used to treat high blood pressure, and benign prostate hypertrophy (BPH) because the combination of tadalafil and an alpha-blocker may lower the blood pressure greatly and lead to dizziness and fainting. Examples of alpha-blockers include tamsulosin (Flomax), terazosin (Hytrin), doxazosin (Cardura), alfuzosin (Uroxatral), and prazosin (Minipress). Tamsulosin (Flomax) is the only alpha-blocker that patients can use safely with tadalafil. When tadalafil (20 mg) was given to healthy men taking 0.4 mg of Flomax daily, there was no significant decrease in blood pressure and so patients on this dose of tamsulosin (Flomax) can be prescribed tadalafil. The only alpha-blocker not tested with tadalafil is alfuzosin (Uroxatral), and no recommendations can be made regarding the interaction between the two.
When you become aroused, your brain sends chemical messages to the blood vessels in the penis, causing them to dilate or open, allowing blood to flow into the penis. As the pressure builds, the blood becomes trapped in the corpora cavernosa, keeping the penis erect. If blood flow to the penis is insufficient or if it fails to stay inside the penis, it can lead to erectile dysfunction.
Monitoring erections that occur during sleep (nocturnal penile tumescence) can help you and your doctor to understand if the erectile dysfunction is due to psychological or physical causes. The nocturnal penile tumescence test is a study to evaluate erections at night. Normally men have three to five erections per eight hours of sleep. The test can be performed at home or in a sleep lab. The most accurate way to perform the test involves a special device that is connected to two rings. The rings are placed around the penis, one at the tip of the penis and the other at the bottom (base) of the penis. The device records how many erections occur, how long they last, and how rigid they are. The test is limited in that it does not assess the ability to penetrate.

Many men gain potency by injecting drugs into the penis, causing it to become engorged with blood. Drugs such as papaverine hydrochloride, phentolamine, and alprostadil (marked as Caverject) widen blood vessels. These drugs may create unwanted side effects, however, including persistent erection (known as priapism) and scarring. Nitroglycerin, a muscle relaxant, sometimes can enhance erection when rubbed on the surface of the penis.

Three forms of penile prostheses are available for patients who fail with or refuse other forms of therapy: semirigid, malleable, and inflatable. The effectiveness, complications, and acceptability vary among the three types of prostheses, with the main problems being mechanical failure, infection, and erosions. Silicone particle shedding has been reported, including migration to regional lymph nodes; however, no clinically identifiable problems have been reported as a result of the silicone particles. There is a risk of the need for reoperation with all devices. Although the inflatable prostheses may yield a more physiologically natural appearance, they have had a higher rate of failure requiring reoperation. Men with diabetes mellitus, spinal cord injuries, or urinary tract infections have an increased risk of prosthesis-associated infection. This form of treatment may not be appropriate in patients with severe penile corporal fibrosis, or severe medical illness. Circumcision may be required for patients with phimosis and balanitis.


A lot of guys don’t want to admit it, but not being able to get or keep an erection happens more often than you’d think. Guys usually have trouble getting or keeping an erection when they’re nervous, scared or worried about something. They might be worried about how they’ll “perform,” or they could be feeling guilty about having sex. They might be afraid of getting a sexually transmitted disease (STD), or, if they are with a girl, getting their partner pregnant. Drugs (including some anti-depressants) and alcohol can also prevent you from getting and/or maintaining an erection.
The information provided does not constitute a diagnosis of your condition. You should consult a medical practitioner or other appropriate health care professional for a physical exmanication, diagnosis and formal advice. Health24 and the expert accept no responsibility or liability for any damage or personal harm you may suffer resulting from making use of this content.
Diabetes is a well-recognized risk factor for ED. A systematic review and meta-analysis found that the prevalence of ED was 37.5% in type 1 diabetes, 66.3% in type 2 diabetes, and 52.5% in diabetes overall—a rate approximately 3.5 times higher than that in controls. [39]  The etiology of ED in diabetic men probably involves both vascular and neurogenic mechanisms. Evidence indicates that establishing good glycemic control can minimize this risk.
#4 You’re just plain turned off. It happens. Whether it’s the weight your partner has put on, the realization that you’re having period sex, or you’re just not getting what you need in the bedroom, at some point in your life, you’re going to be turned off enough to lose *or be unable to attain* your hard-on. [Read: Not attracted to your girlfriend anymore? The why and the fixes]
Trauma to the pelvic blood vessels or nerves can also lead result in ED. Bicycle riding for long periods has been implicated as an etiologic factor; direct compression of the perineum by the bicycle seat may cause vascular and nerve injury. [37] On the other hand, bicycling for less than 3 hours per week may be somewhat protective against ED. [37] Some of the newer bicycle seats have been designed to diminish pressure on the perineum. [37, 38]
PDE5 inhibitors, the primary second-line therapy, have been the mainstay of ED treatment since the release of sildenafil (Viagra) in 1998, with the subsequent development of many others, and still more in the development stage. These medications do improve erectile quality for the majority of men, and they work by enhancing blood flow in the corpora cavernosa. These medications are generally used on demand and need to be taken about an hour before sexual intimacy. Tadalafil (Cialis) is longer acting and does come in a daily preparation potentially eliminating the ‘on-demand’ need. The daily dosing of tadalafil, 2.5–5 mg\day, has also been approved by the FDA for treatment of symptoms of BPH.41 PDE5 inhibitors are contraindicated in men taking nitrates, but otherwise PDE5 inhibitors are very safe and effective. When PDE5 inhibitors are coadministered with nitrates, pronounced systemic vasodilation and severe hypotension are possible. Many patients with ED are elderly and have the same risk factors as patients with CAD, so these drug combinations are commonly considered or encountered in clinical practice.42
Whenever I am prescribing a medication to a patient, I’m always asking myself, what can the patient do before requiring the medication? What changes do they have to make in order to reduce the amount of medication or preclude their even needing it? So a good candidate is somebody who has an understanding of a healthy lifestyle, about physical activity, about sleep, about nutrition, alcohol, smoking. So patients, individuals, have to do their share before they’re a candidate for anything. All right?
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