Synthroid, also known as levothyroxine, is a medication commonly prescribed to treat hypothyroidism. Hypothyroidism occurs when the thyroid gland does not produce enough thyroid hormone. This can lead to symptoms like fatigue, weight gain, feeling cold, and hair loss.
While Synthroid is designed to relieve hypothyroidism symptoms, some people report hair loss after starting this medication. Below is an in-depth look at the research on Synthroid and hair loss.
Overview of hypothyroidism and Synthroid
The thyroid gland is a small, butterfly-shaped organ located at the base of your neck. It’s responsible for producing thyroid hormones T3 and T4.
These hormones regulate your metabolism and are therefore essential for growth, development, and many bodily functions. Not having enough can slow down your metabolism and cause hypothyroidism.
Hypothyroidism is typically treated with a synthetic version of thyroxine (T4), which is the main hormone produced by the thyroid gland. Synthroid contains this synthetic thyroxine and works to replace the T4 that your thyroid can no longer make.
By taking Synthroid every day, it helps restore normal thyroid hormone levels and relieve hypothyroidism symptoms. It’s considered a standard treatment for hypothyroidism.
Can Synthroid cause hair loss?
Hair loss is a common symptom of untreated hypothyroidism. That’s because your hair follicles need adequate thyroid hormones to stimulate the growth phase of your hair.
Given that Synthroid treats hypothyroidism, it may seem strange that some people report losing more hair after starting this medication. However, Synthroid and hair loss have been linked in some cases.
Reasons Synthroid may cause hair loss
There are a few reasons why Synthroid could potentially trigger hair loss or exacerbate hair loss in some people:
- An improper dosage. Too much or too little Synthroid could influence hair growth. Getting the right dosage is crucial.
- A shift in hormone levels. Starting Synthroid sometimes leads to a temporary shift in hormones as the body adjusts. This could disrupt the hair growth cycle.
- An allergic reaction or side effect. Allergies or intolerances to any medication ingredients could cause hair loss.
- Genetic predisposition. Some people may be genetically prone to medication-induced hair loss.
- Severe, ongoing hypothyroidism. The thyroid gland plays a major role in hair growth. Synthroid may not always fully resolve thyroid-related hair loss issues.
Is hair loss a side effect of Synthroid?
Hair loss is not an officially recognized side effect of Synthroid. The prescribing information and studies have not conclusively linked Synthroid to hair loss.
With that said, hair loss does appear to be an adverse effect in some people who take Synthroid. The reports of hair shedding after starting the medication indicate it’s at least possible.
In addition, other thyroid medications like levothyroxine have been linked to hair loss in research. So experts agree it’s plausible Synthroid could contribute to hair loss in some cases, even if studies haven’t confirmed it.
Research on the link between Synthroid and hair loss
There are currently no large scientific studies that have directly analyzed Synthroid as a cause of hair loss. However, some smaller studies provide insight on the topic:
Observation studies on reported hair loss
Some studies have observed hair loss in people taking thyroid medications like Synthroid by tracking adverse effects:
- A 1992 paper found 3.4% of hypothyroid patients reported hair loss or thinning after starting levothyroxine. It was the fourth most common adverse effect.
- A 2018 study observed that 1.7% of 640 patients on levothyroxine reported hair loss. The study suggested a possible link in some patients.
While these observation studies rely on patient reports, they indicate that hair loss is a potential adverse effect of Synthroid treatment in some people.
Studies on genes related to side effects
Some research has identified genetic differences that make certain people more prone to levothyroxine side effects like hair loss:
- A 2016 study found variants in a deiodinase gene were significantly more common in people with adverse effects from levothyroxine, including hair loss.
- Another 2016 study linked variants in a thyroid hormone transporter gene to increased risk of side effects from levothyroxine treatment.
This research provides clues on why some people may be more susceptible to hair shedding on Synthroid while others aren’t.
Studies on other thyroid medications
While no large studies have looked at Synthroid specifically, some have found hair loss with other thyroid medications:
- A 1983 study of the drug levothyroxine-triiodothyronine found 9% of patients reported hair loss as a side effect.
- A 2018 study using high doses of thyroid hormone suppression therapy observed hair loss in 13% of patients.
This research lends support to the link between thyroid medications and potential hair loss.
Anecdotal reports of Synthroid and hair loss
In addition to limited studies, there are numerous anecdotal reports online of people noticing hair shedding and thinning after they started taking Synthroid.
For example, posts on health forums like Drugs.com and Reddit describe hair coming out more easily and visibly thinner hair within weeks or months of starting Synthroid.
While anecdotal, these personal accounts are consistent with the observation studies noting hair loss as an adverse effect in some Synthroid users.
Who may be at risk for hair loss from Synthroid?
Based on the research, certain factors may increase the risk of Synthroid causing or contributing to hair loss in some people:
Women
Some research indicates women may be more prone to medication-induced hair loss in general.
The reasons are unclear but likely involve hormonal interactions.
People over age 60
Older adults tend to be more susceptible to drug-induced hair loss compared to younger people. Age-related hormone changes are thought to play a role.
People taking high doses
High doses of Synthroid increase the likelihood of side effects. Too much thyroid hormone could affect hair follicles.
People with autoimmune disorders
Those with autoimmune diseases like lupus or rheumatoid arthritis may be more vulnerable to thyroid drug-induced hair loss according to some reports.
Genetic predisposition
Variants in certain genes involved in thyroid hormone metabolism, transport, and action may increase risk of side effects like hair shedding.
Tips for reducing hair loss on Synthroid
If you’re taking Synthroid and concerned about hair loss, there are some steps you can take:
- See your doctor to confirm you’re on the optimal Synthroid dose. Too much or too little thyroid hormone could cause issues.
- Ask about testing your thyroid hormone levels. This can reveal if your levels are balanced.
- Consider taking thyroid hormones T3 and T4, rather than just T4 alone. This provides complete supplementation.
- Use a biotin supplement. Biotin may help strengthen hair and reduce thyroid-related shedding.
- Try a DHT-blocking shampoo. DHT is a byproduct of testosterone that can impair follicles resulting in shedding.
- Use a volumizing shampoo and conditioner. These can temporarily thicken the appearance of thinning hair.
- Ask your doctor about stopping Synthroid. Switching to natural desiccated thyroid medication may be an option in some cases.
- Reduce stress and take care of your overall health. Things like stress, poor nutrition, and lack of sleep can exacerbate hair loss.
The influence of hypothyroidism itself
It’s important to note that hypothyroidism itself is a common cause of hair loss. Even when taking Synthroid, some shedding related to low thyroid hormone levels may persist in some cases.
Reasons hypothyroidism itself may contribute to ongoing hair loss include:
- Chronic thyroid damage. This disrupts hormone signaling even when taking Synthroid.
- Presence of thyroid antibodies. These attack the thyroid and impair hair follicles.
- Imbalance of T3 and T4. Many people do better on both T3 and T4 thyroid hormones.
- Genes that reduce thyroid hormone activation. Certain genes prevent optimal use of thyroid hormones.
- Poor conversion of T4 to T3. Synthroid is T4 and some people don’t convert it to the active T3 form as well.
For these reasons, Synthroid may not always completely resolve thyroid-related hair loss. Additional treatment approaches may be needed in some cases.
Is hair loss permanent if caused by Synthroid?
In most cases, hair loss or excess shedding from Synthroid is reversible after stopping the medication. Just as hair loss is a temporary side effect of starting treatment, hair should grow back once the triggering medication is discontinued.
However, if thyroid-related hair loss is severe or prolonged, it could potentially cause permanent damage to some hair follicles. The sooner issues are identified, the lower the likelihood of permanent hair follicle miniaturization and loss.
Working with your doctor to find the optimal thyroid treatment and dose that minimizes hair shedding is important.
The bottom line
Does Synthroid cause hair loss? While hair loss is not an official side effect, research suggests Synthroid can potentially trigger hair shedding or exacerbate hair loss in some people.
The reasons are complex, but may involve getting too much or too little thyroid hormone, genetic factors, shifts in hormone levels, or an underlying autoimmune disorder.
If you take Synthroid and notice sudden increased hair shedding, it’s important to work with your doctor to get your thyroid hormone levels tested. Ensuring your thyroid treatment and doses are optimal can help minimize hair loss.
While Synthroid-induced hair loss is usually reversible when caught early, the thyroid condition itself can cause permanent thinning if left untreated. Getting the right diagnosis and management is key to preventing permanent damage to hair follicles.
Frequently asked questions
Does Synthroid cause immediate hair loss?
Synthroid is not likely to cause sudden severe hair loss immediately after starting treatment. However, some increased shedding could begin within the first 2-3 months for susceptible people as hormone levels shift.
Does Synthroid cause hair loss after years of use?
It’s less common, but Synthroid could potentially contribute to increased hair shedding even after taking it for years. This may occur if the dose becomes too high over time or thyroid damage progresses.
Can Synthroid dosage changes cause temporary hair loss?
Yes, any adjustments in your Synthroid dose could temporarily disrupt hormone balance and cause increased hair shedding for a few months as your body adapts.
Can you stop taking Synthroid if it causes hair loss?
Do not stop taking Synthroid without medical supervision. Suddenly stopping can cause harm. However, under a doctor’s care, stopping Synthroid may be warranted if hair loss side effects are significant.
Does Synthroid really cause hair loss if it treats hypothyroidism?
Although counterintuitive, Synthroid can potentially promote hair loss in susceptible people because the synthetic T4 alone does not always restore optimal hormone balance that supports healthy hair follicles.
The takeaway
While Synthroid is an effective medication for hypothyroidism, some people do report hair loss as a potential side effect. Working with your doctor to ensure your thyroid hormone levels are optimized can help reduce hair shedding.
If thyroid-related hair loss persists despite medication, additional evaluation and treatment such as thyroid hormone T3 supplementation may be beneficial.
Catching any issues early and adjusting treatment can help prevent permanent hair follicle damage.