Let me start by saying that I am not a medical professional. I am just relating my experience and informal research. Almost all cyclists get saddle sores occasionally. These are areas of your skin that may be raised and are usually painful to the touch. They look like an acne zit. These most often occur in places that experience pressure while cycling, your bottom. Since they are painful to touch, they make sitting rather uncomfortable.
Saddle sores occur where rubbing creates a small break in the skin that then gets infected. This means there are two approaches to preventing saddle sores, prevent the skin break or prevent the infection. Cycling specific clothing is made so there are no seams in the bottom or crotch area. This decreasing the chances of a seam rubbing a break in the skin. For this to work you should not wear underwear while cycling. The edge of the underwear would act like a seam in the clothing. Additionally applying cycling specific cream to the area will lubricate and soften the skin decreasing the chance of a break. Look for Chamois Butter, Cycle Glide, Bliss Chamois Cream, Nut Butter, Udderly Smooth Chamois or similar products. These are sold in any bike shop. You may apply this to the seat pad in your shorts, but most people apply directly to their skin.
Another consideration is finding a saddle that fits and is most comfortable for you. It may be counterintuitive but a soft, squishy saddle may cause more rubbing. A harder saddle may be a better choice in the long run. The bike itself should fit your body and be adjusted specific to you. Many people rave about having a professional bike fit. A bike that is not properly adjusted to your anatomy will create uneven pressure increasing the chance of saddle sores.
In order to prevent infection always start your ride with freshly laundered clothes. After your ride shower as soon as possible and dress in fresh clothes. Remember bacteria multiply in sweaty, damp clothes. If you are not able to shower, immediately after riding then wash up and put clean underwear on in a rest room to get that bacteria away from your skin.
Most experienced cyclists have their favorite remedies they use when they get saddle sores. The intent is to reduce inflammation (and therefore pain) and to speed healing. Diaper rash cream or Preparation H are popular treatments but the one that makes the most sense to me is antibiotic cream. You may choose to continue cycling with a minor case of saddle sores, not much difference sitting on a chair at home or your saddle.
If your saddle sores do not improve in a few days, it is important to see your doctor for medical advice. Listen to your doctor’s advice and not advice gleaned for the internet, including yours truly.