Scalp Zits

Scalp zits or scalp acne
Q: Is it safe to get a haircut with scalp zits?
A: Scalp acne is a condition you definitely want to advise your stylist that you have (although a good stylist will do a scalp examination prior to any hair service - even a cut). Depending on the regulations in your area of the world, your stylist may not be ALLOWED to cut your hair when you have an acne breakout on the scalp.
In cases where it isn't prohibited, the stylist will need to know in advance so that he or she can take proper sanitation and infection protocol measures. Zits do constitute bodily fluids and can be a source of infection transmission, both to and from the client who has them.
That being said, if there are no regulations against it, then it is relatively safe to perform a haircut on a client with scalp acne. Your stylist will need to use caution when combing through the hair so as to avoid causing lacerations on the breakout areas, but with a little careful action, you should be fine.
Now that we've covered what CAN be done when you have scalp zits, let's talk about what they are and how to combat them. Aside from the fact that the hair follicles on the scalp produce terminal hair (thicker and coarser) the skin of the scalp is little different from the skin of the face. In fact, individuals who are acne prone, tend to have acne on the scalp as well. It can range from inconvenient to very painful in some cases.
Acne can form from different causes: it can be a result of clogged pores and excess oil, or it can be hormonal. If yours is of the former variety, you can simply use your normal acne-fighting facewash (containing salicylic acid) to wash your scalp. Just focus the effort on massaging the lather into the scalp and not working it through the hair. Avoid applying products containing benzoyl peroxide to the scalp as these can actually lighten the hair color (especially for color-treated hair).
If you need a conditioner, use a spray-on, leave-in conditioner that you can keep off the scalp so as to avoid increasing the oiliness of the scalp.
Now, if your acne doesn't respond to this kind of treatment or you know that it is hormonally caused, talk to your doctor about the situation. There are medications that are useful in treating severe acne (especially in adults).
See also:
Scalp problems
Can I get pimples on my scalp if I leave the towel on my head longer than I should?
My pores get clogged easily. Where can I find non-comedogenic shampoo and conditioner?