Some studies have found that very high doses of the chemicals in hair dye may cause harm. But you are exposed to very low amounts of chemicals when colouring your hair and the colours in permanent and semi-permanent hair dyes are not highly toxic.
There are some things you can do if you’re concerned. For example, many women wait until after 12 weeks of pregnancy (after the first trimester), when the risk of the chemicals harming the baby is lower. It’s also always a good idea to do a strand test first using the hair dye you intend to use (or ask your hairdresser to do a patch test if you’re having your hair dyed at a salon).
You can also reduce risks by:
- wearing gloves
- leaving the dye on for the minimum time
- opening the windows to avoid breathing in the chemicals
- rinsing your scalp when the dye is applied.
Semi-permanent pure vegetable dyes, such as henna, can be a safe alternative.
You could also try having your hair highlighted by a hairdresser. Using this technique means that the chemicals are only absorbed by your hair, not your scalp or bloodstream.
Remember that pregnancy can also affect your hair's normal condition. Hormone changes may mean that dyes don't necessarily affect your hair in the same way, so the results may not be what you expect even if you use the same dye you’ve used before.
There is limited information about using hair treatments when you’re breastfeeding, but it is thought to be fine. Very little of the chemicals in hair dye enter your bloodstream, so it’s unlikely that much will be passed through your breast milk. There are no known negative effects of using hair treatments while breastfeeding.