The color number and color shade indicating the finished color are generally printed on the front of the product package.
(A larger number may indicate a darker color, or vice versa depending on the manufacturer.)

Check the brightness, dyeing, and color shade by looking at the color chart on the side or back of the product.

To help you better understand hair dyes (quasi-drugs) before making a purchase, all products, regardless of the manufacturer or brand, have warnings listed in a prominent location on the upper front of the product.

• Never use this product if you have ever developed an allergic reaction after coloring your hair.
• Oxidative hair dye may cause an allergic reaction.
• Perform a skin allergy test (patch test) every time before coloring your hair.

In addition to warnings on the front of the product, other cautions are included on the package (most are found on the sides of products)

• Please read the instruction leaflet carefully before using. Always use the product correctly.
• Do not use this product if you have experienced the following.
  • If you have ever had an allergic reaction after coloring your hair, including but not limited to this product.
  • If you have ever felt sick during or immediately after coloring your hair.
  • If you have ever experienced any skin reactions as a result of skin allergy test (patch test).
  • If you have a sensitive scalp or skin (if you have an illness, are recovering from an illness, are menstruating, pregnant, etc.)
  • If you have any swelling, a wound, or a skin disease on your head, face, or neck.
  • If you have a pre-existing kidney disease, blood disorder, etc.
  • If you have persistent symptoms indicating poor physical condition (low fever, fatigue, palpitations, shortness of breath, purpura, bleeding easily, excessive menstrual or other bleeding, etc.)
• Protect your eyes from the mixture and rinse water.
• Do not use to color your eyebrows or eyelashes
• Keep out of reach of young children
• Keep in a cool place away from direct sunlight.

A variety of information in addition to warnings and cautions is included on the product, including the information required when contacting the manufacturer.

Repeated use of hair coloring products while failing to notice an allergic reaction or due to mild reactions, or reuse after reactions have subsided can be dangerous because your reactions can gradually become more severe. In rare cases, a serious allergic reaction known as anaphylaxis (generalized hives, difficulty breathing, etc.) may occur suddenly. Even if your reaction is only itching but is felt or intensifies with each use, you may be allergic to hair dyes (quasi-drugs). You should not use any oxidative hair dyes in the future. Use semi-permanent hair dyes such as hair manicures or non-oxidative hair dyes. If you have ever had a reaction after coloring your hair, do not perform a skin allergy test either.

An “allergic reaction caused by a hair coloring product refers to a reaction whose symptoms include itching, swelling, redness, and bumps on the head, hairline, face, neck, and other areas that come in direct contact with the coloring mixture or rinse water. In some cases, you may only experience itching. Even if your reaction is only itching after coloring your hair, if you experience these reactions and they intensify with each use, you may be having an allergic reaction. If the allergic reaction is allergic contact dermatitis (delayed-type hypersensitivity response), it typically begins with a slight itch about six to twelve hours after coloring your hair. This is followed by the onset of symptoms of an allergic reaction such as intense itching, swelling, redness, and a rash. The reaction is most severe 48 hours after coloring your hair. In more severe cases, your entire face may swell, exudate may be emitted from your scalp, or the allergic reaction may spread to areas that were not in contact with the coloring mixture. If you observe these symptoms after coloring your hair, seek medical attention immediately.

A skin allergy test (patch test) is the most effective way for customers to check for allergic reactions to hair coloring products by themselves before coloring their hair. Even with products that you have used safely in the past, allergic reactions can occur suddenly. Perform a skin allergy test every time 48 hours before coloring your hair. The test area should be observed twice, about 30 minutes after application of the test solution and 48 hours later. Skin reactions observed at the test area include itching, swelling, redness, or a rash. Severe skin reactions may expand to areas around the test area. After a skin allergy test (patch test), if no reactions are found, you can color your hair with the product you purchased. In case of any reactions, please contact the manufacturer or seek medical attention from a dermatologist.