Is it possible for you penis to shrink ? Or could it just be all in my head
Depends how old you are, it does tend to shrink with old age I'm told.
I was told by one member on here to Google it when I asked a question.
so I'm not so active on here since then.
I doubt if the penis actually shrinks although obviously the erections may get less firm and so the penis will grow less as you get older - or so I'm told!
Other things can affect the look of the length. Cold weather and excess weight may make it look smaller when not erect.
Nothing really can be done to make it bigger - creams and the like are a waste of time. In South Park they told the boy that circumcision would make it bigger but - again - a myth i fear
People can be so awful
I'm 72 and have that to look forward to then? hasn't really happened yet!
The penis does shrinks a bit as you get older and also when you exercise as a protective measure.
I pleased to inform you that a healthy male genitalia is unlikely to shrink other than in extremely cold ambient conditions.
There have been cases where when a man puts-on a great deal of weight the penis appears to have deminished in size, but in reality it is still the same size as it was previously, but less of it is visible.
In reply to some previous posts concerning your question, I agree that the penis itself doesn't shrink once it has grown to its adult length. But some replies have suggested that cold may reduce its size. This is not true. However, the scrotum will automatically shrink when subjected to cold temperatures because the testicles need to be kept at body warmth. It's nature in action. Try taking a cold shower and you will see what I mean! But then look at your penis and you will find it tends to 'stand up' up little, as if half erect. 
An Harvard Health Publications confirms that the penis actually shrinks during hot and cold temperatures but returns back to normal. Also, If a man does have constant erections, his penis shrinks. Erections keeps the penis in shape
On the contrary, frequent erections are very good for penis health, engorging it with blood and replenishing the tissue. This can increase its size incremently, much like the use of a penis vacuum pump.
Oh snaps! That should have read
Oh snaps! That should have read "doesn't have constant erection"
I am interested to hear from exactly which research base you retrieved this information?
What a difference "does" and "doesn't" makes!
No matter what a Urologist tells you..yes penis can atrophy. In my case low thyroid had indirect relationship on penis size especially flaccid size.Diabetes, heart issues also decrease penis size. Have your testosterone and thyroid checked along with other lab work yiur doc suggests.Good luck
Although genetics defines potential size of genitals many health factors influence penis size. ...other than temperature. .!
My penis has shrunken greatly in the last 5 months in flaccid state.First urologist I saw about that just shrugged his shoulders...it all started after I masturbated and ejaculated and thenot felt tingling on left side of penis.the tingling became greater and flaccid side became more and more small.Present urologist said pains I had sign of prostatitis ...however when I blunt asked him if an infection can cause that type of shrinkage he said no.when I asked for ultrasound of penis to check blood flow..he said even if it showed that vascular surgery is specialty and recommended well known urologist surgeon that I knew of before. That was nice of him.I have been so depressed about this ...and would rather have felt with the previous year of sever scrotum pain that has subsided.I would rather have a more serious illness that did not effect my penis and sexual performance.I am not married and very sad..if I had had a wife and children already this would be so easier to deal with
Wish me luck.
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For the past 3 months been reading this forum specially MIchele123 posts, I'm 60 and never had health problems.
My problem began 8 months ago with light pain inside head of penis during erection, saw doctor and gave me antibiotics that did nothing, then 3 months later I noticed 25% shrinkage.
Saw 2 more doctors and blood tests showed everything within limits except glucose (105) one doctor said I was pre-diabetic, I cut down sugar and exercised, 4 months pased and everything stayed the same
I blamed andropause for my problem and started adjusting to my new reality as I saw no improvement and continued on with my life. A week ago I finally started to see some changes and feeling relieved from my ordeal.
Hope this may help somebody else.
My penis shrinks after I workout / do exercise. Seems just a normal thing that happens and it goes back eventually.