Why do I have these lines under my eyes? Most importantly how do I get rid of them? I'm only 18 btw so not age wrinkles. (photo)

Lines are combination of things including genetics, age, and allergy. These are likely dennie morgan folds which are due to allergy/eczema on the skin.  In general however, light lasers and peels work very well to treat this if you do not have eczema.  I suggest seeing a cosmetic physician who specializes in these types of treatments.  Best, Dr. Emer.

This does look like those Dennis morgie lines which per the picture looks like could be allergic or atopic dermatitis...I would advise to see if the patient is using any creams of lotions that make (the redness on the skin) worse and stop that offending agent, start the patient on low dose steroid for 1 month, control the atopic then relax the obicularis oculi muscle to soften the lines with botox

Pretty much any line on your face is due to the way the muscles contract and fold the skin. You have a muscle that goes around each of your eyes which closes them. This will create lines any time it is flexing. Often times these lines under the eyes are prominent in people who smile a lot or who squint their eyes as they smile. If they really bother you, a few units of botox in the upper cheeks would soften the lines. If you are ever in St. George I'd be happy to help you.