Did you know that about 25 percent of all erectile dysfunction cases are caused by some type of medication side effect? This is one of a few reasons why erectile dysfunction (ED) is more common among men as they get older. Older men tend to be on at least one medication to a number of different medications. It is possible that at least one of them is causing side effects that result in ED.

1. Antidepressants: These substances are some of the biggest antidepressants like Prozac, Paxil and Lexapro can decrease libido and actually delay ejaculation. These drugs do delay ejaculation can make an effective treatment option for men who suffer from premature ejaculation.

2. Blood pressure medications: These most definitely decrease blood flow to the penis which can exacerbate the effects of blood vessels that have already been damaged by high blood pressure. Some studies have showed that these drugs can cause erectile dysfunction. Beta blockers both decrease blood flow and also lower the heart rate making blood flow to the penis more difficult.

3.Antihistamines: As a whole these substances work to decrease blood flow to the penis. They're quite common across prescription substances such as Benadryl, Claritin and Zyrtec. Doctors also often prescribe these drugs to manage nausea, relax stiff muscles and induce sleep. 

4. Illegal substances: Yes, cocaine, methadone and marijuana can impair the ability to get an erection because it decreases the arousal response to stimuli in the brain. 

5. Alcohol also can dull the brain's ability to respond to sexual stimulation but it also has some additional risks associated with long-term use. People who drink heavily for long periods of time put themselves at risk for liver damage which can bring about other health issues including erectile dysfunction by decreasing testosterone levels.