OBAGI - C® Rx C-Therapy Night Cream

Obagi-C® Rx C-Therapy Night Cream is a 57g PM topical cream containing hydroquinone USP 4% (40mg/g), together with vitamin C and vitamin E. It is the evening hydroquinone formulation within the Obagi-C Rx system.

The cream is used, when prescribed, for the gradual lightening of melanin-related hyperpigmentation, including melasma, chloasma, freckles and solar or senile lentigines, commonly described as sun spots or age spots.

Product information

• Product: Obagi-C Rx C-Therapy Night Cream
• Prescription active ingredient: Hydroquinone USP 4%
• Hydroquinone strength: 40mg per gram
• Additional formulation ingredients: Vitamin C and vitamin E
• Formulation: Topical night cream
• Quantity: 57g / 2oz bottle
• Product designation: PM
• Route of administration: External topical use
• Skin types: Normal, dry, combination and oily skin

Indication

The prescribing information describes Obagi-C Rx C-Therapy Night Cream as a topical hydroquinone treatment for the gradual lightening of hyperpigmented skin conditions. These include:

• Melasma or chloasma
• Freckles
• Solar or senile lentigines, often called sun spots or age spots
• Other unwanted areas of melanin-related hyperpigmentation where hydroquinone has been prescribed

Not every form of skin discolouration results from excess melanin or is suitable for hydroquinone. The pigmentation concern and proposed treatment area should therefore be assessed before use.

Hydroquinone 4%

Hydroquinone is the prescription active ingredient in Obagi-C Rx C-Therapy Night Cream. It acts on the process through which melanocytes produce melanin.

The prescribing information states that topical hydroquinone inhibits the enzymatic oxidation of tyrosine to 3,4-dihydroxyphenylalanine, also known as DOPA, and suppresses other melanocyte metabolic processes. This produces a gradual and reversible reduction in pigmentation within the treated area.

Vitamin C and vitamin E

The formulation contains ascorbic acid, a form of vitamin C, and tocopheryl acetate, a form of vitamin E. These are antioxidant formulation ingredients included alongside hydroquinone in the cream base.

The prescribing information identifies hydroquinone 4% as the medicinal active ingredient. Although the product contains vitamins C and E, the product-specific label does not state that C-Therapy Night Cream contains 10% vitamin C. The 10% claim associated with other Obagi-C products should therefore not be applied to this cream without product-specific evidence.

PM formulation

C-Therapy Night Cream is labelled as a PM product and is designed as the evening treatment within the Obagi-C Rx system. It is supplied as a cream rather than the liquid dropper formulation used for the C-Clarifying Serums.

It can be used as an individual prescribed product or as part of an Obagi-C Rx programme. The prescribed application schedule determines how it should be combined with other skincare products.

Obagi-C Rx and Obagi-C Fx Night Cream

Obagi-C Rx C-Therapy Night Cream contains prescription hydroquinone 4%. It should not be confused with Obagi-C Fx C-Therapy Night Cream, which is a separate hydroquinone-free cosmetic formulation containing arbutin.

The Rx and Fx products have similar names and packaging roles but different active-ingredient profiles and regulatory statuses.

C-Therapy Night Cream and Nu-Derm Blender

Obagi-C Rx C-Therapy Night Cream and Obagi Nu-Derm Blender #5 both contain hydroquinone USP 4% and have substantially overlapping listed ingredient profiles. However, they are separately labelled products belonging to different Obagi systems:

• C-Therapy Night Cream: The PM hydroquinone cream within the Obagi-C Rx system, with vitamins C and E identified in the formulation.
• Nu-Derm Blender #5: The number 5 PM blending cream within the Obagi Nu-Derm system.

The products should not be assumed to be interchangeable solely because they contain the same concentration of hydroquinone.

Ingredients

Prescription active ingredient: Hydroquinone USP 4% (40mg/g).

The manufacturer lists the following inactive ingredients:

Water, glycerin, cetyl alcohol, PPG-2 myristyl ether propionate, sodium lauryl sulfate, TEA-salicylate, lactic acid, phenyl trimethicone, tocopheryl acetate, sodium metabisulfite, ascorbic acid, methylparaben, disodium EDTA, propylparaben, saponins and BHT.

Manufacturer formulations and labelling can change. Anyone with a known ingredient sensitivity should check the ingredient information supplied with the current bottle before use.

How C-Therapy Night Cream is applied

The product bottle identifies C-Therapy Night Cream as a PM formulation. Apply it only according to the directions provided with the individual prescription.

The manufacturer’s general prescribing information states that a thin application may be used once or twice daily, or as directed by the prescribing clinician. The timing, amount and frequency stated on the individual prescription take precedence over general product information.

• Apply only to the intended treatment area.
• Treatment should be limited to relatively small areas at one time.
• Avoid contact with the eyes, nose, mouth and lips.
• If accidental contact occurs, rinse the area thoroughly with water.
• Use appropriate sunscreen and protective measures during treatment and afterwards.

Sun protection

Exposure to sunlight or ultraviolet light can sustain melanocyte activity and contribute to repigmentation. The prescribing information therefore identifies sunscreen use as an essential part of topical hydroquinone treatment.

Sun protection should be used consistently during treatment and afterwards, together with any additional protective measures included in the prescribed skincare programme.

Response and treatment duration

Hydroquinone produces a gradual response rather than an immediate change in pigmentation. The manufacturer’s prescribing information states that use should be discontinued if no improvement is seen after three months.

The previous description’s claim that improvement may be seen within four to six weeks has not been retained because the product-specific prescribing information does not establish that outcome for every user.

Skin sensitivity and precautions

The manufacturer advises testing for sensitivity by applying a small amount to an unbroken area of skin and checking it within 24 hours. Minor redness may occur. Stop using the cream and obtain advice if itching, blister formation, an excessive inflammatory response or another sign of hypersensitivity develops.

Transient redness or mild burning can occur, and occasional localised contact dermatitis has been reported.

C-Therapy Night Cream contains sodium metabisulfite, which may cause allergic-type reactions in susceptible individuals. Sulfite sensitivity is reported more frequently in people with asthma.

Do not use the product if you have previously experienced an allergic reaction to hydroquinone or another ingredient in the formulation. The safety of topical hydroquinone during pregnancy and in children aged 12 or under has not been established. Caution is also advised during breastfeeding.

Clinical information

The manufacturer’s prescribing information establishes the product’s hydroquinone concentration, labelled indications, pharmacological mechanism, formulation ingredients, administration range and precautions.

Published hydroquinone studies may involve different formulations, treatment combinations, study periods and patient groups. Results from an individual study should not therefore be presented as product-specific evidence for C-Therapy Night Cream unless this exact formulation was studied.

Storage

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

Frequently asked questions

What is Obagi-C Rx C-Therapy Night Cream?

It is a 57g PM prescription cream containing hydroquinone USP 4%, together with vitamin C and vitamin E. It is the evening hydroquinone product within the Obagi-C Rx system.

Does Obagi C-Therapy Night Cream contain hydroquinone?

Yes. The Rx formulation contains hydroquinone USP 4%, equivalent to 40mg of hydroquinone per gram.

Does the cream contain vitamin C and vitamin E?

Yes. Its ingredient list includes ascorbic acid, a form of vitamin C, and tocopheryl acetate, a form of vitamin E.

Does C-Therapy Night Cream contain 10% vitamin C?

The product-specific prescribing information confirms the presence of ascorbic acid but does not assign a 10% vitamin C concentration to this night cream. It should therefore not be described as containing 10% vitamin C.

What is Obagi-C Rx C-Therapy Night Cream used for?

The prescribing information describes use for gradually lightening hyperpigmented conditions such as melasma, chloasma, freckles, solar or senile lentigines and other unwanted areas of melanin hyperpigmentation.

Is C-Therapy Night Cream suitable for oily skin?

The manufacturer lists it for normal-to-dry, normal-to-oily and combination skin. Individual suitability also depends on skin tolerance and the prescribed treatment programme.

Is Obagi-C Rx the same as Obagi-C Fx C-Therapy Night Cream?

No. The Rx night cream contains prescription hydroquinone 4%. The Fx version is a separate hydroquinone-free cosmetic formulation containing arbutin.

Is C-Therapy Night Cream the same as Obagi Blender?

No. Both contain hydroquinone 4% and have similar listed ingredient profiles, but C-Therapy belongs to the Obagi-C Rx system while Blender #5 belongs to the Nu-Derm system.

Is this cream used in the morning or evening?

The product is labelled as a PM night cream. Follow the timing and application frequency stated on the individual prescription.

How often is C-Therapy Night Cream applied?

The general prescribing information states that a thin application may be used once or twice daily or as directed. Its product presentation is marked PM, and the individually prescribed schedule should be followed.

How long does hydroquinone take to work?

The response is gradual and varies according to the pigmentation condition and individual skin response. The manufacturer states that use should be discontinued if no improvement is seen after three months.

Why is sunscreen important?

Ultraviolet exposure can sustain melanocyte activity and contribute to pigmentation returning. Sunscreen and other protective measures are therefore an important part of hydroquinone treatment.

What should I do if the cream causes irritation?

Mild transient redness or burning can occur. Stop applying it and obtain advice if there is itching, blistering, excessive inflammation, persistent irritation or another suspected allergic reaction.

Further ingredient information

Hydroquinone: UK status, formulations and product information