Hair products and treatments to pause during pregnancy: a careful list

Pregnancy brings a lot of questions about everyday products, and hair care is no exception. Can you still colour your hair? Is a salon smoothing treatment safe? What about the minoxidil or finasteride you were using for thinning hair? This guide sets out a careful list of hair products and treatments that are worth pausing, postponing or checking with your doctor during pregnancy, along with the reasons. It also explains what is generally considered reasonable, and what to do if you used something before you knew you were pregnant.

(This is general information, not personal medical advice. Your own doctor or midwife knows your situation and should guide your decisions.)

Short answer

Hair loss medicines are the clearest items to stop. Finasteride is for use in men only, and women who are or may become pregnant should not even touch broken or crushed tablets ¹. Spironolactone is not usually recommended during pregnancy ². If you use minoxidil, tell your doctor if you are pregnant or planning a pregnancy ³. Salon smoothing treatments that release formaldehyde when heated ⁴, and straighteners containing glyoxylic acid, which has been linked to kidney injury ⁵, are sensible to postpone. Hair dye is a smaller concern: the NHS says most research, although limited, shows it is safe to colour hair during pregnancy, and suggests simple steps to reduce exposure ⁶. For anything else, ask your doctor, midwife or pharmacist.

Why caution makes sense, even when evidence is thin

Pregnant women are rarely included in clinical trials of cosmetic products or hair loss treatments, so for many products there is simply not much data. Dermatologists have recognised a practice gap caused by an incomplete understanding of how safe many dermatological medicines are in women before, during and after pregnancy, which is why a major review of the subject was updated in 2024 ⁷. A review of common pregnancy questions for family doctors concluded that the effects of hair dye or hair straightening products on fetal development or newborn outcomes are unclear ⁸.

"Unclear" does not mean dangerous. It means that, for products you can easily do without for a few months, pausing is a reasonable choice. For products that matter to your health, the decision belongs with your doctor.

The careful list at a glance

The sections below explain each item.

Hair loss medicines

Finasteride

Finasteride blocks the conversion of testosterone to a more potent hormone, dihydrotestosterone. MedlinePlus states that finasteride is only for use in men, and that women who are or may become pregnant should not touch broken or crushed finasteride tablets, because this may harm the fetus. If a woman who is pregnant or could become pregnant touches broken or crushed tablets, she should wash the area with soap and water immediately and call her doctor ¹.

This matters in two ways. First, women who were prescribed finasteride off-label for hair loss should stop before trying to conceive and use it only under medical guidance. Second, if your partner takes finasteride, the tablets should be stored safely and not split or crushed where you could handle them. Topical finasteride products also contain the medicine and should be avoided in pregnancy. See Finasteride for hair loss: how it works and what to discuss with a doctor.

Spironolactone

Spironolactone is sometimes prescribed off-label for female pattern hair loss. The NHS says spironolactone is not usually recommended during pregnancy because it can potentially affect a baby's development ². If you take it and are planning a pregnancy, talk to your doctor about when to stop. See Spironolactone for female hair loss: how doctors use it.

Minoxidil

Topical minoxidil is the most widely used hair loss treatment for women. MedlinePlus advises telling your doctor if you are pregnant, plan to become pregnant or are breastfeeding, and calling your doctor if you become pregnant while using it ³. Because safety data in pregnancy are limited, the usual cautious choice is to pause it unless your doctor advises otherwise. Oral minoxidil, sometimes prescribed at low doses, is a blood pressure medicine taken by mouth and needs the same conversation.

Stopping minoxidil may lead to some extra shedding over the following months, and some of the benefit gained may fade. This is expected and is not a reason to continue against medical advice. You can discuss restarting after pregnancy, and whether it is suitable while breastfeeding. See Minoxidil for women: use, expectations and cautions and Hair loss while breastfeeding: what to ask before using treatments.

Salon chemical treatments

Formaldehyde-releasing smoothing treatments

Many salon "keratin" or "Brazilian" smoothing products contain formaldehyde, also called formalin or methylene glycol. When the solution is heated, formaldehyde is released into the air as a gas. Formaldehyde can irritate the eyes, nose, throat and skin, repeated contact can cause skin sensitisation, and it is classified as a human carcinogen. The FDA advises checking labels and asking salons whether products contain these ingredients ⁴. A review of hair cosmetics notes that straightening procedures carry health concerns, especially for pregnant women ⁹. Postponing smoothing treatments until after pregnancy is a simple, low-cost choice. For more detail, see Keratin and protein treatments: do they help thinning hair?

Straighteners with glyoxylic acid

Some "formaldehyde-free" straighteners use glyoxylic acid. A 2024 paper described a patient with three separate episodes of acute kidney injury, each after a hair-straightening treatment with a glyoxylic acid cream, and showed in mice that glyoxylic acid applied to the skin was absorbed and caused calcium oxalate deposits in the kidneys. The authors concluded such products should be discontinued ⁵.

Relaxers, rebonding and other chemical straightening

A systematic review found that chemical straighteners were associated in some studies with scalp eczema, scaling, pain, burns, inflammation and hair loss, and that long-term effects remain unknown ¹⁰. Their effects on a developing baby are unclear ⁸. Pregnancy can also change how hair responds to chemical treatments ⁶, so results may be less predictable. Many women choose to postpone these treatments. See Hair fall after rebonding: breakage or real hair loss?

Hair dye: usually acceptable, with precautions

Hair dye is the question pregnant women ask most often. The NHS says most research shows it is safe to dye or colour hair while pregnant. The chemicals in hair dyes may cause harm only in very high doses, and the scalp does not absorb much dye, especially when it is healthy. Some people choose to wait until after the first 12 weeks, when the risk of chemicals harming the baby is lower ⁶.

The NHS suggests these steps ⁶:

• do a strand test first, even with a dye you have used before, because hair may react differently in pregnancy
• if a salon colours your hair, tell them you are pregnant and ask for a patch test
• wear gloves, as skin can be more easily irritated in pregnancy
• leave the dye on for the minimum time and do not exceed the maximum time
• use a well-ventilated room
• rinse the scalp thoroughly afterwards
• consider highlights, which keep dye on the strands rather than the scalp, or a pure vegetable dye such as henna

Allergy is a separate issue. Many hair dyes contain PPD (paraphenylenediamine), which can irritate skin or cause allergic reactions, and a past black henna tattoo can raise the risk. Reactions can take up to 72 hours to appear ¹¹. "Black henna" is not the same as pure henna. See Hair dye and hair loss: allergy, breakage and safety.

Elective hair procedures

Hair transplant surgery, platelet-rich plasma (PRP) injections, microneedling and scalp micropigmentation (SMP) are elective. They involve local anaesthetic, needles or other medicines, and they have not been studied in pregnancy. Pregnancy and the months after birth also bring large changes in shedding, so results would be hard to judge. Postponing these procedures until after pregnancy, and usually until postpartum shedding has settled, is the cautious approach.

What is generally reasonable

• Mild shampoo and conditioner as usual.
• Gentle styling and loose hairstyles that do not pull on the scalp.
• Volumising shampoos and light conditioners if hair feels flat. The American Academy of Dermatology suggests these for new mothers with postpartum shedding ¹².
• Medicated shampoos or scalp treatments only after checking with a pharmacist or doctor, who can consider the ingredient and how often you use it.
• Supplements only as advised by your doctor or midwife. A daily prenatal vitamin with at least 400 mcg of folic acid is commonly recommended ⁸. "Hair vitamins" are not a substitute and may duplicate ingredients.

Hair changes to expect during and after pregnancy

Many women notice thicker-feeling hair during pregnancy and heavier shedding a few months after giving birth. The American Academy of Dermatology explains that this postpartum shedding is a form of telogen effluvium caused by falling oestrogen levels, that it is temporary, and that most women see their hair return to normal fullness by their child's first birthday ¹². Postpartum shedding can sometimes reveal another hair loss condition that was developing underneath ¹³. See Hair changes during pregnancy: what is normal and Postpartum hair loss: timeline, reassurance and red flags.

If you used something before you knew you were pregnant

This is common, because many pregnancies are not confirmed until several weeks in. Stop the product, keep the packaging or note the name, and tell your doctor or midwife what you used, how often and for how long. For finasteride, spironolactone or oral minoxidil, contact your doctor promptly. A single hair dye or salon treatment is generally a low exposure, but it is still worth mentioning at your next antenatal appointment so that your care team has the full picture.

When to see a doctor

See a doctor or tell your midwife if:

• you were using a prescription hair loss medicine and are pregnant or planning a pregnancy
• you had a skin reaction, swelling or breathing difficulty after hair dye
• your scalp is red, burning or blistered after a salon treatment
• you feel unwell after a straightening treatment, especially with nausea, vomiting, back pain or less urine
• you have patchy hair loss, a very itchy or scaly scalp, or shedding that continues well beyond the first year after birth

Life in Malaysia

In Malaysia, many women see a government klinik kesihatan or a private obstetrician during pregnancy. Bring your list of hair products and medicines to your first antenatal visit, including anything bought online. Salon rebonding, smoothing and colouring are popular, so ask the salon what a product contains before booking, and tell the stylist you are pregnant. Cosmetic products sold in Malaysia must be notified to the National Pharmaceutical Regulatory Agency (NPRA) ¹⁴, but notification does not mean a product has been tested in pregnancy. If you wear a hijab, loose, breathable fabrics and allowing hair to dry before covering may help scalp comfort. If you are buying products from a pharmacy, see Hair loss products at the pharmacy: what to ask the pharmacist. You can check that a doctor is registered with the Malaysian Medical Council ¹⁵. For an overview of treatment options after pregnancy, see Hair loss treatment in Malaysia: a plain guide to your options.

Bottom line

During pregnancy, stop finasteride and avoid handling crushed tablets, discuss spironolactone and minoxidil with your doctor, and postpone formaldehyde-releasing smoothing treatments and glyoxylic acid straighteners. Chemical straightening and elective procedures can usually wait. Hair dye is generally considered acceptable with sensible precautions, and some women wait until after the first trimester. Most pregnancy and postpartum hair changes settle with time. When in doubt, ask your doctor, midwife or pharmacist before you use a product.

Frequently asked questions

Can I use minoxidil while pregnant?

Tell your doctor if you are pregnant or planning a pregnancy. Because safety data in pregnancy are limited, it is usually paused unless your doctor advises otherwise.

Is finasteride safe in pregnancy?

No. Finasteride is for use in men only, and women who are or may become pregnant should not touch broken or crushed tablets because this may harm the fetus.

Can I take spironolactone for hair loss while pregnant?

Spironolactone is not usually recommended during pregnancy because it can potentially affect a baby's development. Discuss stopping it with your doctor before trying to conceive.

Is it safe to dye my hair while pregnant?

The NHS says most research, although limited, shows it is safe. Some people wait until after 12 weeks. Do a strand test, wear gloves, ventilate the room and keep the dye on for the minimum time.

Should I avoid keratin smoothing treatments in pregnancy?

Postponing them is sensible. Many release formaldehyde gas when heated, and some formaldehyde-free products contain glyoxylic acid, which has been linked to acute kidney injury.

Can I get rebonding while pregnant?

The effects of chemical straightening in pregnancy are unclear, and hair may react unpredictably. Many women choose to postpone it.

Can I have PRP or a hair transplant while pregnant?

These are elective procedures that have not been studied in pregnancy. Postponing them until after pregnancy, and until postpartum shedding settles, is the cautious approach.

What if I used a product before I knew I was pregnant?

Stop it, note the name, and tell your doctor or midwife. For finasteride, spironolactone or oral minoxidil, contact your doctor promptly.

Educational content. Not medical advice.