Hair dye and hair loss: allergy, breakage and safety

Hair colouring is common in Malaysia, whether to cover grey hair or for a new look. Many people then wonder whether dye is behind the hair they see in the shower drain. The honest answer is that dye can affect hair in two main ways: by weakening the hair strand, and by causing a skin reaction on the scalp. Both can lead to hair falling or breaking. This guide explains each one and how to colour more safely.

How hair dye affects the hair strand

Hair dyes, shampoos and straightening products can change the structure of the hair fibre and strip away some of its lipids and protein ¹. The AAD notes that dyeing your hair can cause hair damage ².

Damaged hair is fragile and tends to break. Breakage happens along the strand, not at the root, but it can still leave hair looking thinner ². Learn to tell the two apart in hair breakage vs hair loss.

Allergic reactions to hair dye

The second way dye causes trouble is through the scalp. The NHS describes hair dye reactions as fairly common but usually mild. Severe reactions are rare ³.

The main culprit: PPD

Many long-lasting (oxidative) dyes, and some semi-lasting ones, contain a chemical called PPD (paraphenylenediamine) ³. PPD is the most common allergen behind hair dye contact dermatitis. Contact allergy to PPD occurs in an estimated 0.1-2.3% of the general population ⁴.

DermNet notes that darker shades contain more PPD than lighter shades ⁵. This matters in Malaysia, where many people use dark brown or black dye.

You may also be more at risk if you have ever had a black henna tattoo, because the paste can contain high levels of PPD ³.

Symptoms to watch for

Common skin reactions include ³:

• Stinging and burning
• An itchy rash
• Dryness, tightness and soreness
• Blisters

On brown skin, a rash may look darker brown, purple or grey, or be harder to see. Symptoms can take up to 72 hours to appear ³. A mild reaction often shows as an itchy, dry rash on the upper eyelids or the rims of the ears. More severe reactions cause redness, blistering and swelling of the eyelids, scalp, face and neck ⁵.

After a reaction to PPD, lifelong sensitisation is likely, and each later exposure tends to react faster and more severely ⁵.

Can hair dye cause hair loss?

A review of hair dye side effects lists hair loss among the possible effects, alongside contact dermatitis and pigment changes ⁴. In practice, this usually comes from damaged hair breaking, or from an inflamed scalp after a reaction.

Most hair shedding has other causes, such as stress, illness, hormones or genetics. If you are shedding a lot of hair from the root, see sudden severe hair fall and genetic hair loss.

Emergency signs

Serious allergic reactions (anaphylaxis) to hair dye are rare. Get emergency help (999 in Malaysia) if you have ³:

• Sudden swelling of the lips, mouth, throat or tongue
• Fast breathing or difficulty breathing
• A tight throat or trouble swallowing
• Sudden confusion, drowsiness or dizziness

Treating a mild reaction

If you feel a reaction starting, wash your hair and scalp thoroughly with a mild shampoo right away ³. For mild symptoms, a pharmacist can suggest a moisturising cream (emollient) or antihistamine tablets or cream. If symptoms do not go away, a doctor may prescribe steroid cream or tablets, and may refer you to a dermatologist for a patch test ³. Patch testing is the gold standard for diagnosing hair dye allergy ⁴.

How to colour more safely

The NHS suggests these steps ³:

• Avoid products containing PPD, especially if you have reacted to dye or a black henna tattoo before.
• Test the dye on a strand of hair at least 48 hours before use, following the packet.
• Follow the product instructions, and do not leave dye on longer than recommended.
• Wear gloves when applying dye.
• Stop using a dye if you feel unwell or react after a test.
• Choose a temporary dye if you have reacted to a long-lasting one before.

A negative self-test does not rule out a reaction, and DermNet notes that the test itself can sometimes sensitise you ⁵. Treat a test as a helpful check, not proof of safety.

Protecting the hair strand

To limit damage, the AAD suggests ²:

• Leave more time between touch-ups.
• Have only one chemical service at a time. If you want to perm or relax as well as colour, do that first and colour two weeks later.
• Use conditioner after every shampoo.

If you are already losing hair

If you are using a hair loss treatment such as minoxidil, talk to your doctor or pharmacist about timing before colouring, since an irritated scalp can make treatment harder to use. A review of hair cosmetics notes that proper use of hair products may help people stick with their hair loss treatment ¹.

The bottom line

Hair dye can weaken the hair strand and, in some people, trigger an allergic reaction, mainly to PPD. Both can lead to hair breaking or falling. Doing a test first, following instructions, spacing out treatments, and stopping at the first sign of a reaction lowers your risk. See a doctor if your scalp reacts or your hair loss continues.

Frequently asked questions

Does hair dye cause hair loss?

It can. Dye can weaken hair so it breaks, and an allergic reaction can inflame the scalp. A review lists hair loss among dye side effects ^{4 2}.

What is PPD in hair dye?

PPD is a chemical found in many long-lasting dyes and is the most common cause of hair dye allergy ^{4 3}.

How long does a hair dye reaction take to appear?

Symptoms can take up to 72 hours to appear ³.

Is a self-test enough to be safe?

It helps, but a negative test does not rule out a reaction ⁵.

Educational content. Not medical advice.