Generally, the hard capsule shell of propolis is gelatin, the capsule skin of soft capsules is gelatin and glycerol, and the soft capsules contain polyethylene glycol 400 as a chemical emulsifier (emulsifying and dissolving propolis). Different brands of capsule shell have basically the same ingredients, but the difference lies in dissolved substances. Users should find out what chemical additives propolis has. Propolis soft capsules containing a large amount of PEG 400 are not suitable for long-term use, otherwise it will have serious health hazards.