Up to now, I've always broken the pills in half, taking the 50 mg dose, but decided yesterday to try the whole 100 mg, with good results except that I noticed that lights had a blue, eerie tinge to them.   This lasted for about 2 hours.

 
Kind of made me feel a bit trippy.

I have a couples of friends who have experienced the 'blue light' side effect. It's rare but well documented especially at higher dosages. Without getting too much into the science and chemistry, Sidenafil is a PDE5 inhibitor - essentially a muscle relaxer. Rarely it can also be a PDE6 inhibitor that can overly sensitize rod cells in the retina of the eye. These rod cells are most effective at picking up the color blue so your vision becomes dominated by a blue tint. The blue tint effect is generally short lived.

I presume the effect is fleeting, and not injurious to my eyes.

For the vast majority of men, visual side effects are mild and temporary mostly resolving within a few hours. Occasionally visual side effects will continue for days or weeks. From what I've read, in rare cases at high doses with patients with underlying health conditions, there has been permanent vision loss caused by interrupted blood flow to the optic nerve. Always best to discuss your situation with ophthalomogy and/or your primary care physician.

Yep been there and had that happen - no fun!  

The side effects from V were hell on me!  Started off taking 1/4 pill to get a little lift—ok that happened but not hard enough for penetrating intercourse - side effects were mild headache, flushed appearance and the rabbit crapped in my mouth (cotton mouth). In order to get hard enough for penetration, I had to go to full dose - side effects were hellish - cotton mouth for almost 24 hours, horrible headache despite ibuprofen before, blue view, light headed, and real difficulty cumming. Had one hell of a boner but covered, uncovered, handjob, and bbbj wouldn’t trip my trigger enough so I could cum. I was seeing a beautiful young college age girl at the time and she was determined to help me learn my way through using V. Even tried anal - I was hard enough to penetrate - in fact the first time I almost put her eye out because I slid right in.  
Finally gave up and regrouped.  
Switched to the generic version of cilias from the compounding pharmacy. Dosage options were 20mg daily - sort of expensive or on call 2 hours prior with 100mg dose.  Works well!  I get hard flirting, making out and when groped by a woman. Every once in a while I get a 2 shot night but most of the time it’s one shot.  
My play friend commented the last time that she likes feeling me cum in her because she can feel it - some other guys just sort of dribble. I always ask for penetration intercourse for my first nut and sometimes I’ll get a bbbj or handjob. It feels good to pop my nut like an 18year old again!
Explore options!  Don’t forget about diet and weight. I’ve dropped 56.7 lbs, lowered my np, walk 4-10 miles a day and no longer eat a high fat diet.  
Think about it!

Good luck!!

i guess I'm lucky.  I take 150 mg of viagra and only occasionally get a stuffy nose.   200 mg pills are common in Europe.
A doctor friend of mine says 200 mg will probably only give you headache.  

I take 2 x 50 mg tablets and experience both the blue tinge and the stuffy nose, but they dissipate after hours. I also take L-Arginine capsules to boost my nitro oxide level.

A few years ago i tried the generic version and had terrible side effects, dizziness but have never experienced anything like this on the patented version. Have folks noticed this difference?

There should be no difference between the generic and the brand. It could be the source. Did you get sildenafil from a local pharmacy or a foreign website?

Thanks good to know. Reputable local pharmacy. Might have had something to do with other medication, which I am no longer taking.

Sildenafil is typically flushed out of your system in a few hours. Tadalafil stays in your system for 2 days or longer. Since I don't take an ED drug for health reasons, I prefer the option that stays in my system the least amount of time.

I've noticed it can drop my blood pressure significantly. I'm normally around 130 with my usual blood pressure meds. Sildenafil can drop me to 100-110 which is quite noticeable giving that dizziness and sometimes headache. Partial cup of caffeinated coffee gets me back up to normal range. Normally only drink decaf.

What dosage are you taking? The "normal" dosage is 50 mg. I take two 50 mg tabs, that's 100 mg, which is the max. You may want to reduce your intake.

I take about 1 1/2 of the 20 mg dosage. It's more than enough for sustainability.