Thanks for your question, Frightened Turtle! To help answer it, we spoke with Dr. Darius Paduch, urologist and male sexual medicine specialist at New York Presbyterian/Weill Cornell Medical Center, and sex therapist Jenni Skyler, Ph.D., director of The Intimacy Institute for sex and relationship therapy in Boulder, Colorado. Here's what they had to say:
Between 10 and 88% of patients diagnosed with cancer experience sexual problems following diagnosis and treatment. The prevalence varies according to the location and type of cancer, and the treatment modalities used. Sexuality may be affected by chemotherapy, alterations in body image due to weight change, hair loss or surgical disfigurement, hormonal changes, and cancer treatments that directly affect the pelvic region.
All these treatments listed above do not provide immediate effect on your body. If you need an instant erection, you should take a look at the topical erection treatment. Targeted delivery has been recently identified as an emerging alternative to orally administered products mainly due to the current concerns of the side effects that may occur from taking prescription drugs. Topical erection treatment presents a preferable delivery method to get an erection that enhances the desired effect directly to the intended site of action while limiting the exposure of the rest of the body to the ingredients.
Medications: Many common medicines produce erectile dysfunction as a side effect. Medicines that can cause erectile dysfunction include many used to treat high blood pressure, antihistamines, antidepressants, tranquilizers, and appetite suppressants. Examples of common medicines that can cause erectile dysfunction include propranolol (Inderal) or other beta-blockers, hydrochlorothiazide, digoxin (Lanoxin), amitriptyline (Elavil), famotidine (Pepcid), cimetidine (Tagamet), metoclopramide (Reglan), naproxen, indomethacin (Indocin), lithium (Eskalith, Lithobid), verapamil (Calan, Verelan, Isoptin), phenytoin (Dilantin), gemfibrozil (Lopid), amphetamine/dextroamphetamine (Adderall), and phentermine. Prostate cancer medications that lower testosterone levels such as leuprolide (Lupron) may affect erectile function. Some chemotherapies such as cyclophosphamide (Cytoxan) may affect erectile function.
That means that as an adult, you need to activate the opposing parasympathetic system through sexually exciting visuals, thoughts and touches to get an erection going. But this nerve transmission is disrupted if you're stressed, anxious or distracted. The latter because you simply don't develop enough total stimulation of your genitals to get an erection, and the former because stress and anxiety all increase adrenaline – a key transmitter in the inhibiting sympathetic nervous system. They quite literally sabotage your erection.
Maybe your performance issues stem from feelings of discomfort relating to something you've done. Are you having trouble performing because you're feeling uncertain about whether you really love your partner? Or because you feel like you crossed a line in terms of infidelity and now the guilt is tearing you up inside? Maybe your conscience is what's wreaking havoc with your sex.
Erectile dysfunction can occur as a side effect of medication taken for another health condition. Common culprits are high blood pressure meds, antidepressants, some diuretics, beta-blockers, heart medication, cholesterol meds, antipsychotic drugs, hormone drugs, corticosteroids, chemotherapy, and medication for male pattern baldness, among others.
The drugs work best in combination with sex therapy. Several studies have shown this. There’s more to satisfying sex than just an erection. The quality of the relationship is crucial, especially if sex has been a sore point or if the couple hasn’t had much for a while. To find a sex therapist near you, visit the American Association of Sex Educators, Counselors, and Therapists, the Society for Sex Therapy and Research, or the American Board of Sexology.
The mechanisms by which testosterone plays a role in erectile function are not completely understood. A study evaluating the effect of testosterone on erections in surgically castrated rabbits and control animals, in which the rabbits’ intracavernosal pressures were compared after cavernosal nerve stimulation, determined that castrated rabbits had much lower pressures after stimulation than control rabbits did.  Notably, the pressures increased when castrated rabbits received exogenous testosterone replacement.
First realize that this is normal, and just because it happened once does not mean it will happen again (but freaking out about it could make it happen again). Then Skyler tells people to completely ditch the idea that sex is a goal-oriented act with orgasm being the big finish. Instead, take a pleasure-oriented mentality where various sex acts are done because they feel good — not because it's part of series of steps to get you to climax. This helps take away some of the anxiety, because when you're not so focused on the performance, it's not that big of a deal if there's a little bit of stage fright, she says. There's plenty of other things you can do while hanging out with a non-erect penis!
This may be the oldest excuse in the book as a reason not to have safe sex, but research has confirmed that condoms may interfere with some men’s ability to have and hold an erection. For example, a 2006 study found that, over a three-month period, about 37 percent of men lost at least one erection when putting on a condom, or during sex with a condom, SexualHealth.com reported.
Watts and coworkers, in their review article, make several points about this ED/CAD nexus. Endothelial dysfunction is present in both CVD and ED, and is linked through the NO mechanism. The authors note that PDE5 inhibitors improve endothelial function and have a salutary effect on both CVD and ED. Both ED and cardiac disease respond to modifications in lifestyle as well as pharmacologic manipulation. These authors also report that the presence of ED gives the clinician an opportunity to assess CVD and prevention as well.20
Erectile dysfunction (previously called impotence) is the inability to get or maintain an erection that is sufficient to ensure satisfactory sex for both partners. This problem can cause significant distress for couples. Fortunately more and more men of all ages are seeking help, and treatment for ED has advanced rapidly. The enormous demand for “anti-impotence” drugs suggests that erection problems may be more common than was previously thought. Find out more about the causes and treatment of erectile dysfunction here.
Whatever happens, remember there are still ways you can have fun and be intimate even if your partner can’t get an erection. Exchanging sexy texts, reading erotic literature, and indulging in sensual massage can all help to relax, inspire and increase intimacy. Of course, every couple is different and it may take a while to find out what works for you.
The nerves and endothelium of sinusoids and vessels in the penis produce and release transmitters and modulators that control the contractile state of corporal smooth muscles. Although the membrane receptors play an important role, downstream signaling pathways are also important. The RhoA–Rho kinase pathway is involved in the regulation of cavernosal smooth muscle contraction. 
Another potential new treatment consists of penile low-intensity shock wave lithotripsy. This consists of 1500 shocks twice a week for 3–6 weeks. The purpose is to stimulate neovascularisation to the corporal bodies with improvement in penile blood flow and endothelial function. The use of low-intensity shock wave lithotripsy may convert PDE5 inhibitor non-responders to responders.47
Before taking any medication for erectile dysfunction, including over-the-counter supplements and herbal remedies, get your doctor's OK. Medications for erectile dysfunction do not work in all men and might be less effective in certain conditions, such as after prostate surgery or if you have diabetes. Some medications might also be dangerous if you:
Let’s admit that not “talking about anything that could possibly be uncomfortable” is a sure-fire recipe for total disaster. Maybe you’re exaggerating, but if he can’t deal with anything even slightly difficult, then that is a bigger problem than pillow talk. Think about how exactly it would affect everything else in your relationship. He can’t choose not to deal. When good things are happening, it’s a shame he can’t say "I love you0". But when hard things happen, he can’t just say: "Um, pass."
The link between chronic disease and ED is most striking for diabetes. Men who have diabetes are two to three times more likely to have erectile dysfunction than men who do not have diabetes. Among men with erectile dysfunction, those with diabetes may experience the problem as much as 10 to 15 years earlier than men without diabetes. Yet evidence shows that good blood sugar control can minimize this risk. Other conditions that may cause ED include cardiovascular disease, atherosclerosis (hardening of the arteries), kidney disease, and multiple sclerosis. These illnesses can impair blood flow or nerve impulses throughout the body.