What Is Lactase?
Lactose is a sugar present in the milk of all mammals, and all dairy products out there. It can even be “hidden” in breads, cereals, canned and frozen foods, and even medications. When the activity of the lactase enzyme is ineffective, the body can’t absorb the milk sugar properly. Because of this, large amounts of unfermented sugar pass to the large intestine, to get fermented by the normal bacteria residing in the gut. This process may lead to symptoms of lactose intolerance such as gas, explosive bowel movements, and even colic. 
Colicky Pain Due To Lactose Intolerance
About 75 percent of the world’s population loses the ability to digest dairy at some point in their lives, while others don’t have problems with the lactase enzyme even after they pass well into adulthood. 
Rarely, it can happen that a baby is born with lactose intolerance. For this to happen, both parents need to pass the intolerance gene to the baby. This baby would have severe troubles with digestion, including severe diarrhea and wouldn't’ be able to tolerate either breast milk or formula made of cow’s milk. This condition is often confused with a milk protein allergy. 
Most lactase supplements consist of lactase in a water and glycerol solution, which is able to convert lactose into simple sugars when added to expelled breast milk or formula and thus make lactose more digestible.  For babies born with the lack of the lactase enzyme, symptoms usually start to improve when they start producing it around four months of age, and there's no need for lactase drops anymore. This is the approximate age when the colicky pain stops in the majority of infants, right? Scientists may be onto something here.
Because lactase levels increase the most during the last trimester of the pregnancy, prematurely born babies often can’t produce the necessary amounts of lactase, so they may have tummy troubles, including colic. The levels of lactase increase as the baby gets bigger and stronger. Real lactose intolerance usually appears sometimes in the teen years.
Studies On Lactase Drops In The Treatment Of Colicky Pain
Studies support the efficacy of lactase drops in the treatment of colicky pain in infants. They suggest that colic in babies may have multiple causes and origins including lactose intolerance and the treatment of feeds with lactase drops can result in considerable improvements of the symptoms. Lactase drops work best when pre-incubated with milk formula. 
Do You Need Lactase Drops For A Breastfed Baby?
According to experts, it’s important to implement the right breastfeeding techniques to prevent colicky pain in infants. There’s a great book named “How to Breastfeed Your Baby” by a professor of midwifery studies called Mary Renfrew. [6, 7]
It’s important to continue breastfeeding your baby if possible, and for as long as possible. The best way to calm your baby’s upset stomach is to feed them on one breast for as long as possible, as the best way to slow digestion is with fattier milk towards the end of the feeding session. A high carbohydrate diet aids digestive problems, and a breast is full of high carb milk at the beginning of a feeding session.
Let the baby finish one breast completely before offering another, as recommended by Renfrew. This can be tricky — and I know it from experience. My daughter wants the other breast even when there’s plenty of milk left in the first one, just because it’s easier to feed from a full breast. Breastfeeding moms should remain persistent and let the baby finish the first side before switching to the other breast.
It Will Get Better
If the child cries inconsolably even after four months of age, they might have some other underlying condition such as allergies, reflux, a urinary tract infection, or hernia, among many other possible diseases. It’s important to rule other possible conditions before diagnosing colic. This is why it’s strongly advised to take your baby to a pediatrician for well-baby visits. 
If you don’t want to use medications and supplements to treat your baby’s colicky pain, there are plenty other ways to relieve the symptoms and soothe the baby including smaller but more frequent feeds, providing some tummy time, and baby massage. Some babies like being swaddled. Some colicky babies have strong sucking reflex and they find pacifiers soothing, just be careful and don’t introduce a dummy before the breastfeeding is fully established, as offering dummy prior to four weeks old could cause a baby to discontinue breastfeeding. 
The colicky period is hard for babies, but for parents as well. Try different soothing methods and stick to whatever works for you and your family. It may sound like a cliché, but it’s true — colic will pass relatively quickly, and after a while, you won’t even remember it.