I touch upon what sulfa powder as well as morphine here, but I'll repeat it below. As I note, sulfanilamide was essentially obsolete by 1944 with the introduction of large quantities of modern antibiotics such as penicillin (something the Germans attempted to do on an industrial scale like the Allies, but could never really achieve), but it is still in limited use today to treat certain vaginal yeast infections.

The white powder often seen sprinkled on wounds is sulfanilamide, which was used to inhibit the growth of bacteria if a wound was dirty, or until proper disinfectants could be administered in rear areas or during surgery; sulfanilamide was often sprinkled into body cavities as an antibacterial measure during major surgical procedures. Most soldiers were issued with an M1924 or M1942 first aid pouch that had a drab colored tin, brass, steel, or later, a larger wax-dipped cardboard container containing a sterile Carlisle bandage, a 7-inch by 4-inch dressing to be placed on a wound and tied with two attached tie-tapes. In 1941, a box of 12 sulfanilamide tablets was added to the cardboard container (in the case of the smaller metal containers, the tablets wouldn't fit and had to be carried separately in the first aid pouch) later replaced by a smaller packet of 8 tablets or the much more common 5-gram shaker envelope of powder (which did fit in the metal container) by the end of 1941. By 1942, the types of metal container had been completely replaced with the cardboard box due to wartime rationing; a plastic container was trialled in 1943, but not accepted. To identify already-produced containers to which sulfa had been added after the fact, metal ones were painted red, and metal as well as cardboard ones were stamped or imprinted with the words "with sulfanilamide". The sulfa tablets were to be taken with a large amount of water, with water to be consumed for 24 hours afterward, and were not to be administered if no water was available. Sulfa was rendered obsolete by the proliferation of large quantities of penicillin mid-war, and the 5-gram envelope ceased to be included in newly-produced bandage containers in July, 1944.

Morphine syrettes, small metal tubes resembling toothpaste tubes containing a half-grain (~30 mg) of morphine tartrate were quite powerful and capable of knocking out many smaller-framed men completely when combined with the shock of being wounded. To prepare to administer the morphine, the tube was removed from its protective cardboard container, the plastic hood of the syrette removed, and the wire loop provided with the needle used to pierce the metal seal of the container to allow the medication to flow; at least half the needle's length was to be inserted into the patient.

The needle was supposed to be inserted at a shallow angle (not "stabbed" into the patient as seen in Saving Private Ryan) into a convenient location such as the thigh or upper arm. Morphine was not to be given if the victim was;

• Experiencing severe abdominal pain of unknown cause

• Unconscious

• Suffering from depressed respiration (less than 12 breaths per minute)

• Suffering from a head injury

• Administered morphine within the last two hours

• To undergo surgery under general anesthesia

A syrette of morphine's full effects were felt within twenty to thirty minutes, (some effect was nearly immediate) and lasted for three to four hours. A problem during winter months, especially in Italy during fall 1943, was the prevalence of morphine poisoning among wounded men. A man, after being injured, would often fall into snow or some other wet, cold conditions and lie unattended until a medical aid man reached him. When subcutaneous tissues become chilled, injected drugs do not "flow" easily due to poor blood circulation, and they often initially have no effect; men were often injected multiple times. When they were warmed up and the large resultant dose began to take effect, fatal results often ensued.

I touch on the issue of helmet netting here

Sources:

World War II U.S. Army Combat Equipments, by Gordon L. Rottman

Medical Department, United States Army: Surgery in World War II (Volume II, General Surgery), editor-in-chief Colonel John Boyd Coates, Jr., Medical Corps