Pharmaceutical jellies are usually prepared by adding a thickening agent such as tragacanth or carboxy methylcellulose (CMC) to an aqueous solution in which the drug has been dissolved. The mass is then triturated in a mortar until a uniform product is obtained.

The following gelling agents are used for the preparation of jellies.

1. Tragacanth: Bassorin is the main hydrophilic component of tragacanth, which gels in water; hence, tragacanth jellies are sometimes called bassorin paste. The amount of gum required for the preparation varies with its use. For example, for lubricating jelly, 23% and for dermatological vehicles about 5% is used.
2. Sodium alginate: It is available in several grades as compared to tragacanth. Traces of calcium chloride are added to increase the viscosity of the final formulation. It is used as a lubricant jelly in the concentration of 1.5–2% and as a dermatological vehicle with 5–10% concentration.
3. Pectin: Pectin is a very good gelling agent and is an important component of many types of jellies including edible jellies. Glycerin is used as a dispersing agent and humectant in dermatological jellies. It must be packed in well-closed containers because it loses water rapidly by evaporation.
4. Starch: Starch alone is not used, but it is commonly used in combination with gelatin and glycerin for preparations of jellies. Glycerin in the concentration of 50% may act as a preservative and the medicaments are incorporated in the cold jelly by trituration.
5. Gelatin: It is insoluble in cold water but swells and softens in it. It is soluble in hot water. Hot solution containing 2% w/v gelatin forms a jelly on cooling. Very stiff (15%) jellies are melted before use and, after cooling to desired temperature, are applied with a brush on the affected area. The area is covered with bandage and the dressing may be left in place for several weeks. An example is the zinc–gelatin jelly (Unna’s paste).
6. Cellulose derivative: Methyl cellulose and sodium carboxymethyl cellulose produce neutral jellies of stable viscosity. They produce a strong film after drying on the skin, with good resistance against microbial growth. They can be used to prepare lubricating jellies and sterile jellies as they can withstand autoclaving temperature. An example is lignocaine jelly.
7. Clays: The preparations containing 720% of bentonite can be used as dermatological bases. The main disadvantages are that they form opalescent jellies and lack attractiveness. Their pH is about 9.0, and hence they are not suitable for application on the skin. The residue formed after application on the skin is powdery and rather silky.