OBAGI - C® Rx C-Clarifying Serum - Normal To Dry

Obagi-C® Rx C-Clarifying Serum for Normal to Dry Skin is a 30ml topical serum containing hydroquinone USP 4% as its active medicinal ingredient and L-ascorbic acid 10%, the pure form of vitamin C. It is formulated for combination and normal-to-dry skin and is used as part of a prescribed approach to melanin-related hyperpigmentation.

Product information

• Product: Obagi-C Rx C-Clarifying Serum
• Formulation: Normal to Dry
• Active ingredient: Hydroquinone USP 4%
• Vitamin C: L-ascorbic acid 10%
• Product form: Topical liquid serum
• Size: 30ml
• Application period: Morning, unless prescribed otherwise

Indication

Hydroquinone 4% is indicated for the gradual lightening of areas of melanin hyperpigmentation. The prescribing information identifies hyperpigmented conditions including chloasma, melasma, freckles, senile lentigines—commonly described as age spots—and other unwanted areas of melanin-related pigmentation.

The condition being treated, area of application and appropriate duration of use should be determined during consultation.

Hydroquinone 4%

Hydroquinone is the active medicinal ingredient in Obagi-C Rx C-Clarifying Serum. The prescribing information describes topical hydroquinone as producing reversible depigmentation by inhibiting the enzymatic oxidation of tyrosine to DOPA and suppressing other metabolic processes within melanocytes.

This activity reduces the formation of melanin within the treated area. Exposure to sunlight or ultraviolet light can stimulate melanocytic activity and contribute to repigmentation, which is why appropriate sun protection is an important part of treatment.

L-ascorbic acid 10%

The serum also contains 10% L-ascorbic acid, the pure form of vitamin C. Hydroquinone remains the product’s active medicinal ingredient; L-ascorbic acid is listed among the formulation’s inactive ingredients.

Obagi identifies L-ascorbic acid as the antioxidant component of the serum. Its inclusion distinguishes C-Clarifying Serum from hydroquinone-only topical formulations and places the product within the Obagi-C Rx System.

Normal-to-dry formulation

This version of Obagi-C Rx C-Clarifying Serum is specifically formulated for combination and normal-to-dry skin. It contains the same headline concentrations of hydroquinone and L-ascorbic acid as the Normal-to-Oily version, but the two products use different formulation bases.

The published ingredient list for the Normal-to-Dry serum does not include ethyl alcohol or fragrance. These ingredients appear in the separate Normal-to-Oily formulation. The two versions should therefore be treated as distinct products rather than interchangeable listings.

Ingredients

Active ingredient: Hydroquinone USP 4% (40mg per gram).

Inactive ingredients: Propylene glycol, water, ascorbic acid, propylene carbonate and sodium lauryl sulfate.

Always check the ingredient information supplied with the dispensed product in case the manufacturer updates its formulation.

Application

The product-specific label directs users to apply 5–7 drops to the face once daily in the morning and massage the serum into the skin gently. However, the instructions supplied by the prescriber take precedence and may specify a different application area or schedule.

Apply only to the area directed and avoid contact with the eyes, nose, mouth and lips. Wash hands after application unless the hands are the prescribed treatment area.

Sun protection during treatment

Sunscreen use is described in the prescribing information as an essential part of hydroquinone therapy. Even limited sunlight exposure can sustain melanocytic activity and contribute to the return or persistence of pigmentation.

Limit unnecessary sun exposure and use the sunscreen and protective measures recommended as part of the prescribed skincare programme.

Response and treatment duration

Response to hydroquinone varies according to the type, depth and cause of pigmentation, as well as consistency of application and exposure to ultraviolet light. A specific improvement date should not be assumed.

The product label states that use should be discontinued if no improvement is seen after three months. Continued or repeated treatment should follow the prescriber’s instructions.

Clinical information

The clinical rationale for Obagi-C Rx C-Clarifying Serum is based on the established depigmenting action of topical hydroquinone. The formulation combines hydroquinone USP 4% with L-ascorbic acid 10% in a vehicle developed for combination and normal-to-dry skin.

No isolated study result or percentage improvement is presented here because an individual trial outcome cannot predict the response of a particular patient. Product selection depends on the pigmentation being assessed, skin characteristics and the prescribed treatment programme.

Sensitivity and precautions

A small-area sensitivity test may be advised before treatment begins. Temporary redness or mild burning can occur with topical hydroquinone. Stop using the product and seek advice if itching, blistering, marked inflammation, contact dermatitis or another suspected hypersensitivity reaction develops.

Do not use the serum if there is a known sensitivity to hydroquinone or another listed ingredient. The safety of topical hydroquinone during pregnancy and in children aged 12 or younger has not been established.

Storage

Store at controlled room temperature between 15°C and 25°C and keep the bottle out of direct sunlight. Follow any additional storage instructions printed on the supplied packaging.

Frequently asked questions

What is Obagi-C Rx C-Clarifying Serum?

It is a 30ml prescription topical serum containing hydroquinone 4% and L-ascorbic acid 10%. This version is formulated for combination and normal-to-dry skin.

What is the active ingredient?

Hydroquinone USP 4% is the active medicinal ingredient. L-ascorbic acid is included as the serum’s vitamin C component but is listed as an inactive ingredient in the prescribing information.

How much vitamin C does the serum contain?

Obagi-C Rx C-Clarifying Serum contains 10% L-ascorbic acid, the pure form of vitamin C.

What is this serum indicated for?

It is indicated for the gradual lightening of melanin-related hyperpigmentation, including melasma, chloasma, freckles, senile lentigines or age spots, and other unwanted areas of melanin hyperpigmentation.

Is it suitable for dry skin?

This formulation is designated by Obagi for combination and normal-to-dry skin. Suitability also depends on the individual’s skin condition, sensitivities and prescribed skincare programme.

What is the difference between the Normal-to-Dry and Normal-to-Oily serums?

Both contain hydroquinone 4% and L-ascorbic acid 10%, but their formulation bases differ. The published Normal-to-Dry ingredient list does not include ethyl alcohol or fragrance, whereas those ingredients are listed in the separate Normal-to-Oily formulation.

Is Obagi-C Rx the same as Obagi-C Fx?

No. “Rx” identifies this prescription formulation containing hydroquinone 4%. Products carrying the “Fx” name are separate formulations and should not be treated as equivalent to Obagi-C Rx C-Clarifying Serum.

Should the serum be used in the morning or evening?

The product-specific directions state that the Normal-to-Dry serum is applied in the morning. Follow the individual instructions supplied by the prescriber if they differ.

How much should be applied?

The product label specifies 5–7 drops for facial application. The prescribed quantity and treatment area may differ, so the individual directions supplied with the medicine take precedence.

How frequently is it used?

The product-specific label directs once-daily morning use. Use only at the frequency specified by the prescriber.

How long does hydroquinone take to work?

There is no single response time that applies to everyone. Results depend on the type and depth of pigmentation, ultraviolet exposure and adherence to the prescribed programme. The label states that the product should be discontinued if there is no improvement after three months.

Is sunscreen required when using hydroquinone?

Yes. The prescribing information describes sunscreen as an essential part of hydroquinone therapy because ultraviolet exposure can sustain melanocytic activity and contribute to repigmentation.

Can the serum cause irritation?

Temporary redness or mild burning can occur. Stop application and seek advice if there is itching, blistering, substantial inflammation or another suspected hypersensitivity reaction.

What size is the bottle?

Obagi-C Rx C-Clarifying Serum for Normal to Dry Skin is supplied in a 30ml bottle.

Further ingredient information

Hydroquinone: UK status, formulations and product information