Can Viagra be used for erectile dysfunction in Parkinson's disease? Yes: in the one placebo-controlled trial, sildenafil improved erections in men with Parkinson's, with little change in their blood pressure. The caution is multiple system atrophy (MSA), a rarer condition that can look like Parkinson's early on. In the same trial sildenafil caused severe falls in blood pressure in men with MSA, so its authors advise checking blood pressure lying and standing before it is prescribed to any man with parkinsonism.
Does Parkinson's disease cause erectile dysfunction?
It can. healthdirect lists Parkinson's among the nerve conditions that cause erection problems (healthdirect — Erectile dysfunction), and says some people with Parkinson's "have a decrease in sexual desire, performance or satisfaction" (healthdirect — Parkinson's disease). The loss of dopamine affects the nerves that control sexual response, so "men can have problems with getting or keeping an erection" or be unable to ejaculate; Parkinson's medication "can diminish sexual desire and reduce sexual response", and "Some studies have found that depression affects sexuality more than the condition itself in people with Parkinson's disease" (Better Health Channel). Some dopamine medicines work the other way, causing a preoccupation with sexual thoughts (healthdirect — Parkinson's disease).
Does Viagra work for men with Parkinson's?
In small studies, yes. In a randomised, double-blind, placebo-controlled crossover trial that recruited 12 men with Parkinson's, sildenafil — started at 50 mg and adjusted for effect and tolerability — improved their ability to get and keep an erection and the quality of their sex life; it worked in the men with MSA too (Hussain et al., 2001). In an earlier open study without a placebo, 10 men with Parkinson's took 50 to 100 mg over two months; their sexual function improved, their Parkinson's and depression scores did not change, and one man had headaches (Zesiewicz et al., 2000).
Is Viagra safe with Parkinson's low blood pressure?
It needs checking first. Low blood pressure, "especially going from lying to sitting, or sitting to standing", is one of the symptoms of Parkinson's (healthdirect — Parkinson's disease), and sildenafil lowers blood pressure a little — after 100 mg, by 8.4/5.5 mmHg on average at its lowest (EMA — Viagra). In the trial's men with Parkinson's, blood pressure changed little between sildenafil and placebo (Hussain et al., 2001). Viagra is ruled out if your blood pressure "is unusually high or low or is not effectively treated", and the leaflet says not to drive if it makes you dizzy (Viagra CMI). Neither the Viagra nor the Cialis leaflet lists a Parkinson's medicine among those that interact. More on this in can you take Viagra with low blood pressure?
Why is multiple system atrophy different?
Because MSA damages the body's control of blood pressure. It is "a rare and progressive neurological condition"; its early symptoms include erectile dysfunction and "dizziness caused by low blood pressure", and many people are first diagnosed with Parkinson's because the symptoms are similar (Fight Parkinson's — MSA). The sildenafil label names "the rare syndrome of multiple system atrophy manifesting as severely impaired autonomic control of blood pressure" among the conditions that make men more sensitive to its blood-vessel-widening effect (Viagra PI (Australia)). In the trial, six men with MSA had been studied when recruitment was stopped, because three had a severe drop in blood pressure an hour after the dose — two already treated for low blood pressure on standing, the third with low blood pressure but no symptoms, all within the trial's blood-pressure limits. The authors recommend "measurement of lying and standing blood pressure before prescribing sildenafil to men with parkinsonism", and that men seek advice if they get symptoms of low blood pressure on standing (Hussain et al., 2001).
Can Viagra help depression in Parkinson's?
It is not a depression treatment, and the evidence is weak. In an open study of 33 depressed men with Parkinson's taking 50 mg for four months, 84.8% reported better erections and depressive symptoms improved in 75%, which the authors put down "indirectly" to the better erections; there was no placebo group (Raffaele et al., 2002). In the other open study, depression scores did not change (Zesiewicz et al., 2000). If you take an antidepressant, see Viagra with antidepressants.
What else can help?
Timing and talking. The Better Health Channel suggests moving sex to the morning or to your "on" time, when symptoms are less pronounced, counselling with a sexual-health counsellor, and working with your medical team to reduce the effects of medicines on sexual function; it notes that "certain prescription drugs can stimulate an erection" (Better Health Channel). If tablets do not suit, the alternatives include alprostadil injections, vacuum erection devices and counselling (healthdirect — ED medicines).
The short answer
Sildenafil can help erections in Parkinson's disease, and blood pressure changed little in the trial's men with Parkinson's. Because MSA can look like Parkinson's and sildenafil can drop blood pressure sharply in MSA, a lying and standing blood-pressure check comes first, and dizziness on standing after a dose is a reason to call your doctor. Epilepsy is covered in can people with epilepsy take Viagra or Cialis?; other situations are in our guide to Viagra and Cialis with special conditions.
