Formulation & Evaluation of Herbal Medicated Bath Bomb

The skin, being the largest organ of the human body, plays a vital role in protection, regulation, and sensation. Maintaining healthy skin is not only essential for aesthetic appeal but also for overall physiological balance. In the modern era, increased exposure to pollution, stress, and synthetic chemicals in personal care products has led to a surge in dermatological issues such as dryness, irritation, allergies, and premature aging. As a result, there is a rising preference for natural and herbal skincare solutions that are both effective and safe.  Herbal bath bombs have emerged as a novel and luxurious addition to personal care routines, combining therapeutic effects with the soothing experience of a fizzy bath. These products are compact spherical formulations that typically contain a weak acid (citric acid) and a carbonate base (sodium bicarbonate) that react in water to release carbon dioxide, creating an effervescent effect. Unlike conventional bath products that may contain harsh chemicals, herbal bath bombs incorporate natural ingredients such as neem, green tea, beetroot, rose water, honey, and essential oils, which provide multiple benefits including hydration, detoxification, relaxation, and antimicrobial protection. The concept of herbal bath therapy is rooted in traditional medicine, where plant-based ingredients have been used for centuries for their healing properties. Ingredients like neem possess antibacterial and antifungal effects; green tea offers antioxidant and anti-aging benefits; glycerin and honey act as natural moisturizers; and magnesium sulfate (Epsom salt) relieves muscle tension and promotes relaxation. When these ingredients are delivered through a bath bomb, they not only cleanse the skin but also rejuvenate the body and mind through aromatherapy and transdermal absorption. This study is focused on the formulation and evaluation of herbal medicated bath bombs with an aim to develop a natural, skin-friendly, and sustainable cosmetic product. The formulation process emphasizes the use of biodegradable, non-toxic, and eco-conscious ingredients that align with the growing consumer demand for clean beauty products. The prepared bath bombs are evaluated for key parameters such as physical appearance, texture, pH, effervescence duration, spreadability, skin compatibility, and stability to ensure quality, safety, and user satisfaction. In summary, this research aims to contribute to the advancement of herbal cosmetics by introducing an effective and innovative bath care product that combines relaxation with therapeutic skin benefits.

MATERIALS AND METHODS:

Table 1: List of Materials (Composition)

Table 2: List of Equipment

The equipment listed above was used during the preparation and evaluation of the herbal medicated bath bombs. All apparatus were thoroughly cleaned and sanitized before use to maintain hygiene and ensure the accuracy and reliability of the formulation process. Proper handling techniques were followed to avoid contamination and ensure uniform mixing. This helped in achieving consistent texture, shape, and stability of the final bath bomb formulations.

Procedure

The present study was carried out to formulate herbal medicated bath bombs using natural ingredients such as sodium bicarbonate, citric acid, rice starch, magnesium sulphate, neem, beetroot powder, green tea extract, honey, rose water, and essential oils. All raw materials used were of analytical grade, and the preparation was done under hygienic laboratory conditions. The method involved a sequential process of mixing, binding, molding, and drying, followed by evaluation of the final formulation.

1. Preparation of Dry Mixture

All dry ingredients including sodium bicarbonate, citric acid, rice starch, magnesium sulphate, neem powder, beetroot powder, and green tea extract were weighed accurately. These powders were passed through a sieve and blended thoroughly in a clean mixing bowl to ensure uniform distribution of each component.

2. Addition of Moisture Phase

A small amount of distilled water was added gradually using a spray bottle to moisten the dry mixture. Simultaneously, glycerine, rose water, honey, vitamin E oil, and selected essential oils were added dropwise to avoid excessive wetting, which could trigger premature effervescence. The mixture was gently stirred with a spatula to achieve a slightly damp, sand-like consistency.

3. Molding the Bath Bombs

Once the correct texture was achieved (where the mixture held its shape when pressed), it was immediately transferred into clean, dry bath bomb molds. The mixture was firmly compressed into the molds to ensure the structural integrity of the final product.

4. Drying and Hardening

The filled molds were kept in a refrigerator for 30–50 minutes to allow the bath bombs to set. Alternatively, they were left at room temperature to air dry for 24 hours. Once completely dried and hardened, the bath bombs were carefully removed from the molds.

5. Storage

The prepared herbal bath bombs were stored in airtight containers to protect them from moisture and preserve their physical integrity, fragrance, and stability until further evaluation.

Flowchart of Procedure

Evaluation Of Herbal Medicated Bath Bomb

The formulated herbal bath bombs were evaluated for various physicochemical and functional parameters to assess their quality, stability, and suitability for use. The following tests were carried out:

1. Physical Appearance

The bath bombs were visually examined for their shape, color, texture, and presence of any cracks or deformities. A well-formed, smooth surface and uniform appearance indicated proper formulation and compression.

2. pH Determination

To evaluate skin compatibility, the pH of the dissolved bath bomb solution was measured. 1 gram of the bath bomb was dissolved in 100 ml of distilled water and allowed to stand for 30 minutes. The pH was measured using a calibrated digital pH meter. Ideal pH values for skin-friendly products range between 5.0 and 7.0.

3. Effervescence Time

This test assessed the duration of the fizzing reaction when the bath bomb was placed in water. A single bath bomb was dropped into a beaker containing 200 ml of warm water, and the time taken for complete dissolution and effervescence was recorded using a stopwatch.

4. Texture and Hardness

The surface texture and hardness of the bath bombs were evaluated manually to check for brittleness or crumbling. A firm, yet dissolvable structure was considered ideal.

5. Spreadability in Water

Upon dissolution, the dispersion of color, fragrance, and active ingredients in water was visually assessed. Good spreadability ensured even distribution and optimal exposure of skin to active components.

6. Skin Irritation Test

A small amount of the bath bomb solution was applied to a patch of skin on the forearm and observed for 30 minutes to 3 hours. Any signs of redness, itching, or irritation were noted. Absence of such symptoms indicated the formulation was dermatologically safe.

7. Stability Study

The prepared bath bombs were stored under different environmental conditions (room temperature, refrigerated, and high humidity) for 2 weeks. Observations were made for changes in physical appearance, color, texture, and integrity to assess stability.

RESULT AND DISCUSSION

The prepared herbal medicated bath bomb formulations (F1, F2, and F3) were evaluated based on physical properties, effervescent behavior, skin compatibility, pH, and moisturizing potential to determine their suitability as skincare products. The evaluation also considered their aesthetic appeal and consumer-friendly characteristics.

Formulation Composition and Variation

Three formulations—F1, F2, and F3—were developed using the same core ingredients, with slight variation in the concentration of essential oils and herbal extracts to assess their impact on skin feel, fragrance intensity, and therapeutic benefit. All formulations contained a standard base of sodium bicarbonate, citric acid, rice starch, magnesium sulfate, and glycerin. F1 had a higher concentration of rose water and green tea extract, F2 included more neem and beetroot powder for enhanced antibacterial and brightening properties, while F3 combined moderate amounts of all key extracts to offer a balanced therapeutic effect.

Table 3: Composition of Herbal Bath Bomb Formulation

1. Physical Evaluation

All three formulations (F1, F2, and F3) exhibited excellent physical characteristics such as smooth texture, spherical shape, and no visible cracking or crumbling. F1 had a light pink hue and floral fragrance owing to its higher content of rose water and green tea. F2 stood out with a vibrant pink color and an earthy aroma contributed by neem and beetroot, enhancing its aesthetic and functional appeal. F3 shared a similar color and fragrance to F2 but without the same vibrancy. Overall, F2 offered the most visually appealing and distinctive sensory attributes among the three.

Table 4: Physical Evaluation of Formulations

2. pH Evaluation

pH plays a crucial role in determining the skin compatibility of any cosmetic product. The pH of the bath bomb solution was measured by dissolving 1 gm in 100 ml of demineralized water. F1, F2, and F3 exhibited pH values within the range of 5.8, 6.1, and 5.9 respectively, indicating a slightly acidic to neutral range, which is safe and compatible for skin. All three formulations demonstrated pH values within the ideal range for skincare products (4.5–6.5), ensuring skin-friendly action. F1 had a mildly acidic pH of 5.8, F3 followed closely with 5.9, while F2 showed a slightly higher pH of 6.1, aligning well with the skin’s natural pH balance. This slightly elevated pH, combined with the antimicrobial benefits of neem and beetroot, enhances the cleansing potential of F2 while preserving the skin’s protective acid mantle. The balanced pH levels of all three formulations help in preventing irritation, dryness, and microbial invasion, thereby contributing to their dermatological safety and overall effectiveness.

Table 5: PH of prepared Formulations

3. Effervescence and Solubility

All three formulations produced an immediate fizz upon immersion in water and left no residue. F1 dissolved completely in 3.0 minutes, F3 in 3.5 minutes, and F2 in 4.0 minutes. Although F2 had the longest dissolution time, this was likely due to its richer herbal matrix, which allows for a sustained release of active ingredients. Despite the slight delay, F2’s superior herbal load may offer prolonged therapeutic benefits during use.

Table 6: Effervescence and Solubility

4. Skin Irritability Test

None of the formulations (F1, F2, or F3) caused any signs of irritation, redness, or inflammation after 1 and 3 hours of patch testing on human volunteers. This confirms that all three are dermatologically safe; however, F2’s combination of neem and beetroot—both known for their antimicrobial and soothing properties—adds further credibility to its use for sensitive or problematic skin.

Table 7: Skin Irritability Test of prepared formulations

5. Washability and Skin Feel

All three formulations were easy to rinse off and left the skin feeling soft and refreshed. F1 offered enhanced moisturization due to its higher glycerin and rose water content, while F2 provided a balanced skin feel—smooth, hydrated, and nourished. F3 also contributed to a soft and hydrated feel but lacked the distinctive moisturization or antimicrobial edge of the other two. F2, therefore, emerges as the most well-rounded in terms of post-application skin benefits.

Table 8: Washability and Post-Use Skin Feel