Hormones
The pill, the coil, the implant: what contraception does to your hair
The question I get asked most quietly, usually at the end of an appointment, is whether the coil did it. Sometimes it did. More often the timing is a coincidence and the coil is being blamed for a shed that was going to happen anyway. Here is how to tell the two apart, and what each method actually does.
The principle: oestrogen shelters, progestins vary
Oestrogen keeps hair in its growing phase and partly shields the follicle from DHT, the androgen that miniaturises follicles at the temples and parting. Progestins — the synthetic progesterone in every hormonal contraceptive — are a family, and its members differ in how androgenic they are. Some behave a little like testosterone at the follicle; others actively block androgens. That difference is the whole story.
The combined pill
Combined pills contain oestrogen plus a progestin. The oestrogen is generally helpful for hair. Whether the pill as a whole helps or hurts depends on the progestin: levonorgestrel and norethisterone are the more androgenic ones, and pills built on them can worsen thinning in women who are already prone to it; drospirenone, cyproterone acetate, desogestrel and norgestimate are low-androgen or anti-androgen, and pills built on them are, if anything, protective. If you are on a combined pill and your hair is thinning at the temples or parting, it is worth checking which progestin you are on and asking your GP whether an alternative would be reasonable.
The progestogen-only pill, the implant and the injection
These have no oestrogen. The mini-pill and the implant both use a progestin (desogestrel and etonogestrel respectively) that is only mildly androgenic, and most women notice no change. The injection uses medroxyprogesterone and suppresses the ovaries’ own oestrogen more thoroughly; it is the method most consistently linked with hair thinning in the women I see, though the numbers are still a minority.
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The levonorgestrel coil releases a small dose of a relatively androgenic progestin, mostly locally, with a little reaching the bloodstream. Hair loss is listed as a possible side effect and a small percentage of women do get it, typically as a diffuse shed in the first six months. Most do not. If your hair thinned after the coil went in, the honest position is that it might be the coil and it might not, and the way to find out is below.
The swap shed
This is the one nobody warns you about. Any change in hormonal contraception — starting, stopping or switching — can trigger a shed about two to three months later, for the same reason the postnatal shed happens: the follicles were being held in growth by one hormonal state, the state changed, and a cohort of hairs let go together. It is temporary and it corrects itself within six months, but it terrifies women, and because it arrives months after the change nobody connects the two.
If you had the coil out and then started shedding three months later, that is the swap shed. It is not evidence that you should have kept the coil, and it is not evidence that something is now wrong.
How to work out whether it is the contraception
Ask yourself three things. Did it start two to four months after a change? If so, wait it out to six months before deciding anything. Is it a diffuse shed, or is it a pattern — temples, parting, ponytail? A shed is more likely to be the contraception; a pattern is more likely to be the underlying androgen sensitivity that your contraception is either revealing or protecting you from. Have you had children and are you over 35? If yes, the postnatal follicle sensitivity and early perimenopause are both in play, and the contraception is one factor among several.
Where the follicle comes in
Whatever you are taking, the follicle at the temple or parting is still dealing with the same set of problems: the androgen it is sensitive to, its blood supply, low-level inflammation and the growth signals it has stopped receiving. Contraception moves one of those dials. Addressing the others is a separate job, and it is the one this article deals with.
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