Apple's iPhone 6 is selling like, well, iPhones, but some early adopters are complaining the "Plus" model is too darn big to use comfortably. Just how large is this phone-slash-tablet? At over 6 inches long and more than 3 inches wide, the Plus is bigger than a Pop Tart.

While Apple armed the giant gizmo with "reachability"—a feature designed to help you access the entire 5.5 inch screen with one hand—pulling this task off may make even guys' thumbs ache, according to reports.

You can beat smartphone pain no matter what gadget you're using with this advice from hand surgeon Rachel S. Rohde, MD, Assistant Professor of Orthopaedic Surgery at the Oakland University William Beaumont School of Medicine in Rochester, Michigan.

Take a test drive

Before you plunk down your plastic for an iPhone 6 Plus (or any new phone), make sure it feels comfortable in your hands. Going through the texting and app-opening motions is a quick way to gauge if it works for your reach. "As with any instrument, larger hands generally are more comfortable with larger devices and smaller hands feel better using smaller ones," says Dr. Rohde. Want to try an iPhone on for size right in your living room? Print and cut out these handy paper models from Apple Insider.

Watch your funny bones

No more leaning on your elbows and bringing your phone up to your face! "This stretches the ulnar nerve, which we think of as the 'funny bone,' and causes it to lose its blood supply, leading to numbness and tingling in the ring and little fingers," Dr. Rohde explains. Strike this pose too often and you can even lose hand strength, she adds. "I have seen this with excessive texting and with 'addictions' to game apps (interestingly, the latter I see in adults and the former in adolescents!)" The fix is easy: If you do rest on your elbows, make sure they're extended beyond a 90 degree angle.

Don't ignore pain

Touch technology is great because it places very little stress on the tendons and joints, notes Dr. Rohde: "If you remember the old manual typewriters, those were not good for the hands. Now, it takes very little force to 'strike a key.'" Just don't ignore the signs that you're racking up too much screen time (including tingling, cramping, and weakness). Make smart modifications and your pain will get better...just in time for the release of the next big device.