Our skin has millions of pores, which contain hair follicles and oil glands. If pores get clogged with oil or dead skin cells, pimples, whiteheads or blackheads can appear. Sometimes, large painful lumps will even develop under the skin.

“In the winter when your skin becomes dry, your body often responds by producing more sebum. Sebum is an oily substance that is a key component of acne. Too much of this oil causes the skin cells to stick together and clogs pores,” Dr. Zwerner says.

So even if you usually have a clear complexion, blemishes are common during the driest time of year. “Winter leads to a significant drop in the amount of moisture in the air. Mixed with the dry air of indoor heating systems, you have a situation where it’s difficult for people to maintain the proper skin moisture,” Dr. Zwerner says. “This leads to inflammation and a poor skin barrier to the season’s elements.”

These elements of freezing temperatures and windy conditions strip the skin of its necessary moisture. Also, people tend to warm up in too-hot, too-long showers during the coldest months. This further reduces skin hydration. Without the much-needed barrier, bacteria can invade and thrive, leading to irritation.