Hair toner is generally considered safe during pregnancy. The American College of Obstetricians and Gynecologists (ACOG) states that coloring your hair is “usually safe” because very little dye is absorbed through the skin. That said, “generally safe” comes with some nuance worth understanding, especially when it comes to the type of toner, how it’s applied, and when during pregnancy you use it.
How Much Chemical Actually Enters Your Body
The main reason hair toner isn’t a major concern is that your skin acts as a strong barrier. Studies measuring how much dye penetrates the scalp found that only about 0.5% of the active coloring agent is absorbed into the body during a typical application. Further research has shown that even the small amount that does penetrate often reaches only the outermost layers of skin and hair follicles, never making it into deeper living tissue or the bloodstream in meaningful quantities.
This is a crucial distinction. The chemicals in hair toner can be harmful at high doses in lab settings, but the amount you’re exposed to during a single salon visit is orders of magnitude lower than the doses that cause problems in animal studies.
What’s Actually in Hair Toner
Hair toners vary widely in their chemical makeup depending on whether they’re permanent, semi-permanent, or a simple color-depositing gloss. Permanent and demi-permanent toners typically contain some combination of p-phenylenediamine (PPD), resorcinol, ammonia or its substitutes, and hydrogen peroxide. These are the same ingredients found in most permanent hair dyes.
PPD is the ingredient that draws the most scrutiny. It can penetrate skin and be inhaled during application, and animal studies have linked it to developmental abnormalities in embryos, though at doses far exceeding what a single hair appointment delivers. Resorcinol, another common ingredient, can disrupt thyroid function in rodents at very high doses (above 520 mg per kilogram of body weight daily over long periods). However, risk assessments have concluded that the levels found in hair dyes and cosmetics are unlikely to cause thyroid problems in real-world use.
Semi-permanent toners and color-depositing glosses are gentler. They sit on the outside of the hair shaft rather than opening it up with ammonia and peroxide, which means fewer reactive chemicals and less scalp irritation overall.
Why Many Stylists Suggest Waiting Until the Second Trimester
You’ll often hear the advice to wait until after your first trimester. The reasoning is biological: during the first 12 weeks, your baby’s major organs and systems are forming in a process called organogenesis. This is the window when a developing embryo is most vulnerable to outside exposures. Animal studies have shown that some chemicals found in hair products, including phenylenediamine, aminophenols, and ethanolamine (an ammonia substitute), can cause birth defects in animals when administered at very high doses during this critical period.
No human study has proven that a single toner application during the first trimester causes harm. But because the theoretical risk is highest during organ formation, many practitioners recommend playing it safe and scheduling your appointment for week 13 or later.
Occasional Use vs. Occupational Exposure
There’s an important difference between getting your hair toned every few months and handling hair chemicals for a living. A CDC-funded study of cosmetologists found moderately increased risks of miscarriage among those who worked full time and performed a large number of chemical services. Formaldehyde exposure and working in salons with nail sculpting services also raised that risk.
If you’re a hairdresser or cosmetologist who is pregnant, guidelines recommend wearing gloves at all times, working no more than 35 hours per week, avoiding prolonged standing, and ensuring your salon has adequate ventilation. For someone who sits in the salon chair a handful of times during pregnancy, the exposure level is dramatically lower and the associated risk is minimal.
Application Techniques That Reduce Exposure
Not all toner applications involve the same level of scalp contact. If you want to minimize exposure even further, consider techniques that keep chemicals off your scalp entirely. Balayage, highlights, lowlights, and streaks all apply color to the mid-lengths and ends of your hair rather than the roots. Since the scalp is the primary absorption point, these methods significantly reduce the amount of chemical your body encounters.
If you do get a root-to-tip toner or an all-over gloss, a few practical steps help. Make sure the room is well ventilated, or ask your stylist to seat you near an open window or fan. Don’t leave the product on longer than directed. And if you have any cuts, scratches, or irritation on your scalp, consider rescheduling, since broken skin absorbs chemicals more readily than intact skin.
Lower-Risk Alternatives
If you’d rather avoid synthetic dyes altogether, you have options. Vegetable-based dyes and henna (pure henna, not “black henna” which often contains PPD) coat the hair without requiring oxidative chemicals. Semi-permanent color-depositing conditioners and glosses contain no ammonia or peroxide and wash out over several weeks. These products carry fewer chemical concerns because they don’t penetrate the hair shaft or react with your hair’s natural pigment.
Keep in mind that pregnancy hormones can change your hair’s texture and how it responds to color. A shade that looked one way before pregnancy might turn out slightly different now. Doing a strand test beforehand saves you from surprises, and a patch test on your inner arm 48 hours before a full application helps flag any new sensitivities that pregnancy may have triggered.
What the Evidence Actually Shows About Birth Outcomes
One area of research has looked at whether hair dye use during pregnancy affects birth weight or childhood cancer risk. Some studies have found that maternal hair dye use during the first trimester is associated with a slightly elevated risk of childhood acute lymphoblastic leukemia. Another study noted that the risk of abnormal birth weight increased when mothers had both irregular menstruation and a history of hair dye use before pregnancy.
These findings deserve honest context. The observed increases in risk are small, the studies often rely on self-reported data, and they haven’t established that hair dye directly causes these outcomes. Correlation in epidemiological research doesn’t confirm causation, and no regulatory body has concluded that occasional hair dye use during pregnancy is unsafe based on this data. Still, the research is worth knowing about, particularly if you’re weighing whether to use permanent products with stronger chemical formulations or opt for something milder.