According to a 2020 article, PPD is an allergen that can cause allergic contact dermatitis. Along with skin irritation, PPD may also have a link to health problems such as congenital abnormalities (formerly known as birth defects) and liver and blood toxicity.
根據 2020 年的文章，PPD 是一種可能引起接觸性皮膚過敏的過敏原。除了皮膚刺激外，PPD 還可能與健康問題有關，例如先天性異常（以前稱為出生缺陷）以及肝臟和血液毒性。

A 2018 studyTrusted Source found that bleaching hair with peroxide resulted in oxidative damage and protein loss in the cuticle and cortex of the hair.
一項 2018 年的研究 Trusted Source 發現，使用過氧化氫漂白頭髮會導致毛髮的毛小管和髓質出現氧化損傷和蛋白質損失。

Products labeled as “natural” or “organic” may also produce negative effects. Natural sources, such as plants, can still contain harmful or allergenic substances.
標有「天然」或「有機」標籤的產品也可能產生負面影響。天然來源，如植物，仍然可能含有有害或有過敏性的物質。

The Food and Drug Administration (FDA)Trusted Sourcestates that because a product is organic or contains organic ingredients, it does not mean that it is automatically safer.
美國食品藥物管理局（FDA）Trusted Source 聲明，因為一種產品是有機的或含有有機成分，並不意味著它自動更安全。

Additionally, growing evidenceTrusted Source suggests that some hair dyes may contain endocrine-disrupting compounds. These chemicals can mimic the effects of the hormone estrogen and may increase the risk of breast cancer. Namely, research suggests that permanent dyes may contain higher concentrations of aromatic amines, which may be carcinogenicto humans.
此外，越来越多的證據表明一些染髮劑可能含有內分泌干擾物質。這些化學物質可以模擬激素雌激素的效應，並可能增加乳癌的風險。具體來說，研究建議永久性染髮劑可能含有更高濃度的芳香胺，這些化學物質對人類可能具有致癌性。

Other potentially harmful ingredients may include ammonia and toluene. The former is a respiratory irritant that can trigger asthma attacks, and toluene is a known neurotoxin with links to congenital abnormalities, pregnancy loss, and allergic reactions.
其他潛在的有害成分可能包括氨和甲苯。前者是呼吸系統刺激物，可能觸發哮喘發作，而甲苯是已知的神經毒素，與先天性異常、懷孕損失和過敏反應有關。

While these are common ingredients, hair dye options exist that do not use harsh chemicals. People may wish to look at labels or ingredient lists on products to check for chemicals that may be harmful.
雖然這些是常見成分，但存在不使用嚴重化學品的染髮選擇。人們可以查看產品標籤或成分清單，以檢查可能有害的化學物質。

How to repair damaged hair
如何修復損壞的頭髮

The American Academy of Dermatology Association recommends the following hair care tips for dyeing the hair and maintaining general hair health:
美國皮膚科醫學會建議以下染髮護髮建議，以保持頭髮的整體健康：

Use a specially formulated shampoo for color-treated hair.
使用專為染髮頭髮配製的洗髮精。
Stay as close to the natural hair shade as possible, staying within three shades of the natural color and darkening rather than lightening where possible.
盡量接近自然髮色，保持在自然色三個色度內，盡量加深而非淺化。
Protect the hair from the sun by wearing a hat in sunny weather.
在陽光明媚的天氣下戴帽子，保護頭髮免受太陽傷害。
If perming the hair, follow product instructions carefully to avoid any long-term damage. If using a relaxer, consult a professional to ensure safe application.
若要染髮，請仔細按照產品說明書操作，以避免任何長期的損傷。若使用矽膠劑，請諮詢專業人士確保安全使用。
If having multiple treatments, such as coloring, perming, or relaxing, try to space out the time between services.
若有多個治療項目，例如染髮、染髮或矽膠劑處理，請盡量將服務時間間隔開。
Use conditioner after every hair wash, especially on the ends of the hair.
每次洗髮後都使用潤髮精，特別是髮梢。
Minimize heat on the hair, such as from styling tongs, and apply a heat-protective product beforehand.
盡量減少對髮絲的熱量，例如從造型鑷子來的熱量，並在之前使用保護熱的產品。
Choose hair products that match hair type.
選擇符合髮型的髮品。
Protect hair from chlorinated water by wearing a tight-fitting cap when swimming.
游泳時戴緊身頭盔，以保護髮質免受氯氣水的侵蝕。
Carry out a patch test of hair dye before applying it all over to check for any irritation.
染髮前先做小範圍皮膚測試，檢查是否有過敏反應。