is thyroid supplement used for the hypothyroidism
,it is used when body do not make enough hormones for the proper functioning.
All these hormonal supplement drugs have a wide margin of safety and a single dose of 75 micro gram in excess of the normal dose is unlikely to cause any long term complications.
Although in short term higher dose of thyroid hormones can cause palpitations, tachycardia
,but it should not last for too long and probably no treatment is needed for it.
Hope it helps.