Caffeine is a college student’s best friend. But those who don’t have time to sip a 16-ounce cup of coffee or an 8-ounce energy drink are increasingly reaching for a product that packs the same amount of caffeine into a 2-ounce shot.

Sales of these petite potions are reportedly expected to double compared with last year, reaching $700 million. But the caffeine fix can be expensive at around $3 a shot, especially compared with fountain drinks.

“They’re pretty pricey,” said UI senior Katie Johnson.

Johnson started the morning with coffee, then drank a tiny bottle of 5-Hour Energy — the leading brand of energy shots — before work to power through the afternoon.

The shot did the trick, but she said she would rather enjoy a cup of coffee.

At Casey’s General Store, 204 N. Dubuque St., 5-Hour Energy is the most popular energy shot sold, though it doesn’t reign over regular 16-ounce energy drinks, said assistant manager Nicole White.

“We don’t sell as much as you’d think,” she said. “When we do, it’s usually to younger people in the morning before they go to work.”

For those who need a quick fix, the 5-Hour Energy shot promises “zero sugar, zero herbal stimulants, and as much caffeine as a cup of the leading premium coffee” with only four calories.

But the such concentrated doses of caffeine could pose health threats, especially when combined with alcohol or other caffeinated beverages.

Caffeine can make people believe that alcohol consumption won’t affect them, which can lead to abuse problems, said Amy A’Hearn, a registered dietitian with Health Iowa.

“You’re taking a stimulant and a depressant, which is never a good combination,” she said.

Caffeine can also cause major problems when not taken in moderation, according to Angie Reams, substance abuse prevention coordinator at Health Iowa. Increased heart rate, dehydration, and even heart attacks can arise from too much caffeine intake — or mixing more than one caffeinated beverage.

UI senior Kendra Meyer has a prescription for the ADHD medication, Adderall, and said she drinks energy beverages when she studies.

Pairing extra caffeine with prescription stimulants such as Adderall could exacerbate the side effects caffeine already causes, especially if the person taking them doesn’t have a prescription, A’hearn said.

For students who need to stay up all night — to study, work, or party — she discourages using quick bursts of caffeine to keep up with a nonstop schedule. She advises staying away from energy drinks all together.

“The best way for people to have energy is to make sure they’re eating every three to five hours and getting enough whole grains, protein, fruits and vegetables,” A’hearn said.

In the end, the most effective deterrent from the powerful shots may just be their taste.

“I tried a 5-hour energy at the library, but they taste horrible,” Meyer said. “I would rather drink a Red Bull — they cost the same.”