Do I have High Blood Pressure at the age of 23?

I'm 23 and am 5'6 140lbs. I have always had this fear of getting High BP for some reason and when the nurse was taking my BP I started to freak out a little. It was really high so she had me calm down and she took it again and it was 136/80. But I have been kinda sick and taking Mucinex and she said that might also cause it too. All I know is that I have been freaking out and making myself sick because now I am going to die of a heart attack, stroke, and kidney failure in prolly the next 5 years. Once you have High BP you always have it for the rest of your life right? How screwed am I?

First, CALM DOWN. Your blood pressure changes throughout the day in response to stress, both physical and emotional. Freaking out is not going to help things.

Next, hypertension is not some life-long disease. It can be lowered with exercise and proper diet. For those few whose pressure isn't fixed by more typical means, there are prescriptions which you should talk to your doctor about only after trying several other methods.

136/80 is mild hypertension or stage 1 hypertension. I'm 21 and I'm typically in the upper 140s/90s and I'm not about to keel over and die. Unless you are in the 180 or above range you aren't really in any immediate danger, but even mild hypertension left untreated for years and years can wear down your cardiovascular system and then you are susceptible to heart attack, stroke, etc. but at your age it should not be of much concern.

If you still feel anxious you should talk to your doctor and see what he/she recommends.

this sounds like a psychological issue. if you're that worried about it, just exercise and eat healthy. and if you ever do happen to get high blood pressure, you can reverse it with proper diet and exercise.
freaking out about it increases your stress levels which over time will raise your blood pressure because it sends signals to the brain that something is wrong. calm down and start taking control of your life.

It is possible you have HBP at your age, but the worst thing you can do is freak out about it. You should have your Dr. check you for kidney problems. A former co-worker of mine had kidney probs. & he'd been taking blood pressure medication since his late teens.
What you need to do is to buy yourself a home blood pressure monitor. Take a reading every day at the same time of day for 2 weeks & record the numbers. If you have 3 or more readings that are high, top and/or bottom #, then see your Dr. and give the readings to him/her.
Normal BP is considered 120/80 or less. 121-139/81-90 is called pre-hypertension. Higher than that is hypertension.
Typically, yes once you have HBP, you keep it but it can be controlled with meds, diet & exercise. It isn't an automatic death sentence, UNLESS it goes untreated.