If you’re wearing a bra as you read this, chances are overwhelmingly high that it doesn’t fit properly. That’s bad news for more than your looks.

Even though an ill-fitting bra may sound like a trivial problem, it has been linked to a range of health complaints. Yet research has found that up to 85% of women wear the wrong size bra. The harms related to a misfitted bra tend to occur in large-breasted women most often, but women of all breast sizes can be affected. For example…

Problem #1: Neck and back pain. Even though the lion’s share of a bra’s support comes from the bra band, which wraps around the torso just below the bust, many women find it more comfortable to opt for a larger band measurement than what they need. Without adequate support, however, large breasts fall forward, pulling the neck, shoulders and upper back with them, triggering or exacerbating neck and back pain.

To avoid it: Go down a size in the band but up a cup size—for example, from 36C to 34D—to increase support in the band while ensuring adequate space for your breasts. 

Helpful: Always use the outermost hooks when trying on bras. A bra is guaranteed to stretch out with wear, so you want it to fit well—snug, but not uncomfortably so—in the loosest position. This will add several months of life to your bra. As it stretches, move to the next hook, until you get to the first. 

Note: A too-loose bra band also can lead to painful shoulder grooves. That’s because a band that’s not snug forces the straps to do all of the work. If the band rides up in the back, the straps dig in, creating painful grooves in the shoulders of full-breasted women and uncomfortable indentations in smaller- breasted women. Shoulder grooves also can be avoided by going down a band size and up a cup size.

Problem #2: Heartburn. An overly tight band can aggravate heartburn—especially in fuller-figured women who already suffer from this condition. The problem happens mainly when sitting, which pushes the stomach upward, constricting the band and pressing on the diaphragm, the muscle that separates the chest and abdomen. 

Because the diaphragm is positioned where the esophagus and stomach meet, pressure there can make it easier for stomach acid to move into the esophagus, causing discomfort and exacerbating heartburn. 

To avoid it: Try a bra extender. These are small strips of fabric—roughly two inches in length—with hooks on one side and loops on the other. They lengthen the circumference of your bra to give some extra breathing room and cost far less than a new bra (you can find three-packs on Amazon.com for $8). 

A bra extender isn’t meant to be worn for months on end—think of it as a stopgap solution. If you use one and your indigestion improves, that’s a sign you need to purchase a new bra with a looser band. 

Also helpful: Try bumping up the band size and downsize the cup size—for example, go from a 36D to 38C.

Problem #3: Rashes and skin irritation. A poorly fitting underwire is often the culprit here. The problem typically stems from the wire resting on breast tissue and the chest wall. Additionally, breasts that rest on the torso can trap perspiration, possibly causing rashes or even fungal infections.

To avoid it: Consider a bra without an underwire. Many women think a wire lifts, but a good-fitting bra—with or without a wire—is what lifts and shapes. If you prefer an underwire bra, go up a cup size so that all breast tissue fits within the frame of the wire. Underwire bras shouldn’t rub against your skin, and your breasts shouldn’t be touching your torso. 

If you notice redness, irritation or itchiness underneath your breasts, see your health-care provider. He/she may prescribe an antibacterial or antifungal cream. And switch to a bra that holds your breasts up!