In summer season i notice acne,small round with water drops inside,burst when pricked.is it allergy frm heat?

never on my face but on my chest n upper arms.sometimes my neck as well.

Sounds like a classic case of heat rash/prickly heat. People with sensitive skin seem more prone to it that others. If you're pale, sunburn easily, and/or flush substantially from exercise or spicy foods, that's probably you.

The cure is to remove the heat. I know, easier said than done, especially if you work outdoors and/or don't have air conditioning.

There's no lotion or ointment you can apply to make it clear up faster or to prevent it.

Prevention involves staying cool. Do physical labor early in the day. If you need to bake, do it early in the day or late at night. Dress in natural fiber (cotton, linen) rather than nylon or rayon. Wear a hat outdoors. Use fans, blowing right at you, at home. Put your hair up, or pull it back. Dampen your hair and skin. (A spray bottle of cool water, in front of the fan, feels pretty terrific.) Open your windows to take advantage of any cross ventilation. Visit public places which are cooled. Find a seat in the shade. Go swimming or run through a sprinkler. Take a cool shower with Dr. Bronner's Peppermint Castile soap (which leaves the skin feeling cool the way mint you eat leaves your mouth feeling cool).

If you keep heat rash clean (wash gently) and don't scratch or pick, there's no lasting result.