Perhaps it is already too late for prevention. If you have a plugged duct, the next best thing is to treat it aggressively, as early as possible.
Your goal is to get the milk flowing through the affected duct again, and your greatest ally is your baby. The simplest cure is to let your baby nurse the breast empty, and his suction combined with your letdown reflex may open the duct. If his nursing doesn’t immediately provide relief of the pain and pressure, you can position his mouth over your breast to make sure that the area with the plug is getting the strongest force of suction. Point your baby’s nose at the plugged spot and allow him to nurse. Alternately, some women find it more effective to position their babies’ lower lip over the plug. Depending on the location of the plug, positioning yourself to do this may make you feel like a gymnast. An especially effective technique is to get down on your hands and knees with your breast dangling over your baby, so that gravity and suction can work together to eliminate the plug. Your baby may find this very silly, and so will anyone else who might see what you are doing, but the relief will be worth it!
Massage your breast with your hands as you breastfeed, pump, or express, trying to work the plug out. You should rub gently, but with pressure, working in a circular or straight motion, from base to nipple. Also, some women find that they need to support the bottom of their breast with one hand while nursing in order for the breast to drain completely.
If the plug does not release the first time, don’t give up. You may be able to release it using other methods. Try applying a heating pad or hot rice pack, taking a hot shower, or dunking your breast in a basin of hot water before the next feeding. Another effective method of applying heat is to fill a disposable diaper with warm water and press it to the breast. The heat may dissolve the clog. Make sure to offer the sore side first at each feeding, but don’t neglect the other breast. (The last thing you need is a plug on the other side, too.)
Nurse as often as possible, and don’t forget to take care of yourself. To prevent mastitis, you should get plenty of rest and drink a lot of fluids. Spending the day in bed, nursing your baby whenever you can, is a marvelous cure.
Use positioning, heat, and massage liberally until you get your reward: expulsion of the clog. Depending on whether you are nursing, pumping, or hand-expressing milk at the time, you may or may not see the plug come out. If you do see it, don’t be surprised if it looks like a piece of sand, a small strand of spaghetti, or a gelatinous substance. It is basically curdled milk. Rest assured that consuming this clog will not harm your baby. Nothing that comes from your breasts can possibly cause your baby to choke to death, nor are there any poisonous substances in a milk plug. It may pass from you to your baby without either of you realizing it, with a regular swallow of milk. After it passes, you will feel relief of built-up pressure as the milk behind it flows downward.
While waiting for the plug to release, be on the lookout for a white spot on your nipple. If you don’t see one, check again. It might be small. This white spot may be the plug itself, waiting to be expressed, with relief waiting behind it. You may be able to work it out with your fingers, like popping a very tiny pimple. Dissenting opinions exist on whether you should try and remove it yourself with a sterilized needle or let a doctor do it. If you decide to give it a try, you can sterilize a needle over a flame and very carefully remove the plug. Once it is released, don’t be surprised if the milk behind it squirts out with some force. You should feel better immediately afterward.