Hydrogel pads are one of my favorite tricks for treating nipple pain because they also catch breastmilk leaks and keep your bra and shirt off of your sensitive nipples.
Hydrogel dressings were first used to help surgical incisions heal quickly, some smart person figured out they were great for healing sore nipples. We did a comparative study at our hospital on two brands and could see faster nipple healing with the thinner 24 hour hydrogels than a thicker brand that could be used up to 72 hours.
They are as simple as can be. Follow the instructions and use and re-use for 24 hrs, peeling them off for feedings and replacing them right back after a breastfeeding. Rinse your breasts before offering a breastfeeding to get any residue off for baby.
If they are not sticky after being in contact with your skin or your nipple cream, you can rinse them with water, place face up and they will be sticky again after a few minutes.
If you have severe nipple/areola pain (greater than a 3 out of 10) or cracks, it's time to find out the root cause while you are giving your breasts some TLC with gel pads. Consult your local lactation consultant to see if there is something not ideal about your baby's latch. If you have pain from pumping, let's get that suction level down TWO levels BELOW what you would rate as "uncomfortable but not painful." Then let's make sure you are not pumping more than 20 minutes at a time. Please have a lactation consultant watch you pump to see what your nipples and areola do while being pulled into the flange to see if the flanges are too big or too small for you. Pumping and breastfeeding should not be causing nipple damage if the latch is deep and the pump fits correctly.