This is an index of side effect / adverse reaction reports (a.k.a. adverse event reports) related to Synthroid (Levothyroxine) and submitted to the FDA during the sample period of about a year. The information is not vetted and should not be considered as verified clinical evidence.
Reports by Event Outcome
All Cases (860)
Death (15)
Life Threatening Events (13)
Disability (8)
Reports by Reaction Type
Alopecia (86),
Fatigue (83),
Headache (57),
Drug Ineffective (51),
Blood Thyroid Stimulating Hormone Increased (49),
Weight Increased (49),
Feeling Abnormal (49),
Dizziness (47),
Palpitations (46),
Anxiety (46),
Coeliac Disease (44),
Insomnia (43)
Below are a few examples of reports where side effects / adverse reactions may be related to Synthroid (Levothyroxine). For a complete list or a specific selection of reports, please use the links above.
Possible Synthroid side effects in 52 year old female
Reported by a consumer/non-health professional from United States on 2012-08-27
Patient: 52 year old female, weighing 50.8 kg (111.7 pounds)
Reactions: Psychomotor Hyperactivity, Pain, Neck Injury, Fall, Joint Injury, Incorrect Drug Administration Duration, Feeling Abnormal, Hyperthyroidism, Back Injury, RIB Fracture
Drug(s) suspected as cause:
Calcium Carbonate
Dosage: 1200 mg, 1x/day
Indication: Mineral Supplementation
Nicotrol
Dosage: unk
Administration route: Oral
Indication: Smoking Cessation Therapy
Start date: 2011-01-01
Synthroid
Dosage: unk
Indication: Hypothyroidism
End date: 2012-01-01
Synthroid
Dosage: 88 ug, unk
Start date: 2012-01-01
Possible Synthroid side effects in 67 year old female
Reported by a consumer/non-health professional from United States on 2012-08-23
Patient: 67 year old female, weighing 78.9 kg (173.6 pounds)
Reactions: Confusional State, Nasopharyngitis, Weight Loss Poor, DRY Skin, Thyroxine Increased, Constipation, Weight Increased, Respiratory Tract Congestion, Mood Altered, TRI-Iodothyronine Decreased, Alopecia, Insomnia, Onychoclasis, Disturbance in Attention, Memory Impairment
Drug(s) suspected as cause:
Levoxyl
Dosage: 100 ug, daily
Levoxyl
Dosage: 50 ug, unk
Indication: Hypothyroidism
Synthroid
Dosage: unk
Indication: Hypothyroidism
Possible Synthroid side effects in female
Reported by a consumer/non-health professional from Brazil on 2012-08-22
Patient: female, weighing 73.0 kg (160.6 pounds)
Reactions: Cataract, Hypersensitivity, Glaucoma, Pain in Extremity, Headache, Femoral Artery Embolism, Peripheral Embolism, Malaise, Skin Discolouration, Heart Rate Increased, DRY Mouth, Blood Cholesterol Increased, Vasodilatation, Feeling Abnormal, Hypertension
Adverse event resulted in: hospitalization
Drug(s) suspected as cause:
Levothyroxine Sodium
Indication: Product Used FOR Unknown Indication
Levothyroxine Sodium
Indication: Product Used FOR Unknown Indication
Synthroid
Indication: Hypothyroidism
Synthroid
Administration route: Oral
Start date: 2007-01-01
Other drugs received by patient: Propafenone HCL; Eparema; Timolol Maleate; Dimethicone; Dramin B6
Possible Synthroid side effects in female
Reported by a consumer/non-health professional from United States on 2012-08-20
Patient: female, weighing 62.7 kg (137.8 pounds)
Reactions: Coeliac Disease, Palpitations, Drug Interaction, Haematoma
Drug(s) suspected as cause:
Synthroid
Administration route: Oral
Indication: Hypothyroidism
Start date: 2011-01-01
Synthroid
Administration route: Oral
Indication: Hypothyroidism
Start date: 2011-01-01
Other drugs received by patient possibly interacting with the suspect drug: Epinephrine
Indication: Product Used FOR Unknown Indication
Start date: 2010-01-01
Synthroid
Indication: Hypothyroidism
Start date: 2000-01-01
End date: 2011-01-01
Other drugs received by patient: Loestrin 1.5 / 30
Possible Synthroid side effects in 54 year old female
Reported by a consumer/non-health professional from United States on 2012-08-20
Patient: 54 year old female, weighing 72.6 kg (159.7 pounds)
Reactions: Visual Impairment, Hypothyroidism, Condition Aggravated
Drug(s) suspected as cause:
Estring
Dosage: unk, once in three months
Indication: Vulvovaginal Dryness
Start date: 2011-10-01
Synthroid
Dosage: 125 ug, 1x/day
Administration route: Oral
Start date: 2012-06-01
Synthroid
Dosage: 112 ug, 1x/day
Administration route: Oral
Indication: Hypothyroidism
End date: 2012-06-01
Other drugs received by patient: Benicar
Possible Synthroid side effects in 54 year old female
Reported by a consumer/non-health professional from United States on 2012-08-17
Patient: 54 year old female
Reactions: Fatigue, Dysphonia, Oropharyngeal Pain, Tremor, Thyroid Function Test Abnormal
Drug(s) suspected as cause:
Liothyronine Sodium
Dosage: unk
Indication: Thyroid Hormone Replacement Therapy
Synthroid
Dosage: unk
Indication: Thyroid Hormone Replacement Therapy
Xanax
Dosage: unk
Indication: Anxiety
Possible Synthroid side effects in 68 year old female
Reported by a individual with unspecified qualification from United States on 2012-08-14
Patient: 68 year old female
Reactions: Meniscus Lesion, Anxiety, Panic Attack, Pain in Extremity, Thyroid Disorder, Breast Cancer Female, Gastrooesophageal Reflux Disease
Drug(s) suspected as cause:
Crestor
Administration route: Oral
Lexapro
Nexium
Administration route: Oral
Synthroid
Other drugs received by patient: Arimidex
Possible Synthroid side effects in female
Reported by a health professional (non-physician/pharmacist) from United States on 2012-08-10
Patient: female
Reactions: Multiple Sclerosis
Drug(s) suspected as cause:
Synthroid
Possible Synthroid side effects in 81 year old female
Reported by a consumer/non-health professional from United States on 2012-08-10
Patient: 81 year old female, weighing 61.2 kg (134.6 pounds)
Reactions: Weight Decreased, Pain, Chills, Drug Interaction, Headache, Pyrexia, Abdominal Pain Upper, Malaise, Fatigue, Oedema Peripheral, DRY Mouth, Dizziness, Muscle Spasms, Blood Pressure Increased, Vein Disorder, Nausea, Paraesthesia, Anxiety, Panic Attack, Insomnia, Vision Blurred, Gait Disturbance, Influenza
Adverse event resulted in: disablity
Drug(s) suspected as cause:
Aspirin
Dosage: 81 mg, 1 d
Indication: Hypertension
Fish OIL (Fish Oil)
Indication: Product Used FOR Unknown Indication
Hydrocodone Bitartrate
Dosage: 350 mg, as needed (one or two times)
Indication: Spinal Cord Disorder
Lisinopril
Dosage: 30 mg (10 mg, 3 in 1 d)
Indication: Hypertension
Lovastatin
Dosage: 20 mg, d
Indication: Blood Cholesterol
Lyrica
Dosage: 50 mg, 1 d, oral
Administration route: Oral
Indication: Vein Pain
Start date: 2012-07-26
End date: 2012-07-28
Multivitamin
Dosage: unknown
Indication: Product Used FOR Unknown Indication
Oxybutynin Chloride
Dosage: 10 mg
Indication: Hypertonic Bladder
Rivastigmine Tartrate
Indication: Dementia
Synthroid
Dosage: 50 mcg, 1 d
Indication: Thyroid Disorder
Xanax
Dosage: 1 mg, as required)
Indication: Panic Attack
Possible Synthroid side effects in male
Reported by a physician from United States on 2012-08-09
Patient: male
Reactions: Urticaria, Vocal Cord Disorder
Drug(s) suspected as cause:
Revlimid
Dosage: 15 milligram
Administration route: Oral
Indication: Multiple Myeloma
Start date: 2010-01-18
Synthroid
Dosage: 175 microgram
Possible Synthroid side effects in 48 year old female
Reported by a consumer/non-health professional from United States on 2012-08-08
Patient: 48 year old female, weighing 57.2 kg (125.7 pounds)
Reactions: Product Substitution Issue, Bedridden, Respiratory Disorder, Pain, Autoimmune Thyroiditis, TRI-Iodothyronine Decreased, Fibromyalgia, Intervertebral Disc Disorder, Crying, Product Quality Issue, Inadequate Analgesia, Organ Failure, Heart Rate Increased, Gait Disturbance, Thyroid Neoplasm, Arthritis, Iodine Deficiency
Adverse event resulted in: life threatening event, disablity
Drug(s) suspected as cause:
Levothyroxine Sodium
Dosage: all 1x day oral
Administration route: Oral
Start date: 2007-01-01
Synthroid
Dosage: all 1x day pill
Indication: Thyroidectomy
Start date: 2004-01-01
End date: 2008-01-01
Possible Synthroid side effects in female
Reported by a physician from United States on 2012-08-07
Patient: female, weighing 65.1 kg (143.2 pounds)
Reactions: Atrial Fibrillation
Drug(s) suspected as cause:
Synthroid
End date: 2012-05-31
Synthroid
Indication: Hypothyroidism
Start date: 1997-05-01
Possible Synthroid side effects in female
Reported by a consumer/non-health professional from United States on 2012-08-07
Patient: female, weighing 59.0 kg (129.7 pounds)
Reactions: Alopecia
Adverse event resulted in: disablity
Drug(s) suspected as cause:
Levothyroxine Sodium
Dosage: 0.025mg tabs 1 x day by mouth
Administration route: Oral
Indication: Hypothyroidism
Synthroid
Dosage: 0.025mg tabs 1 x day by mouth
Administration route: Oral
Indication: Hypothyroidism
Start date: 2011-07-16
End date: 2012-07-16
Possible Synthroid side effects in female
Reported by a pharmacist from United States on 2012-08-06
Patient: female, weighing 77.6 kg (170.7 pounds)
Reactions: Cellulitis, Headache
Adverse event resulted in: hospitalization
Drug(s) suspected as cause:
Synthroid
Other drugs received by patient: Mediciation FOR Migraines; Metformin Hydrochloride
Possible Synthroid side effects in female
Reported by a consumer/non-health professional from United States on 2012-08-02
Patient: female, weighing 91.0 kg (200.2 pounds)
Reactions: Lyme Disease
Drug(s) suspected as cause:
Cortef
Dosage: 20 mg in morning, 5mg at 2pm
Administration route: Oral
Indication: Hypopituitarism
Start date: 2009-01-01
Hydrocortisone
Dosage: 20 mg in morning and 5mg at 2pm
Administration route: Oral
Indication: Hypopituitarism
Start date: 2009-01-01
Levothyroxine Sodium
Dosage: 50 ug, 1x/day
Administration route: Oral
Indication: Hypothyroidism
Start date: 2009-01-01
Synthroid
Dosage: 50 ug, 1x/day
Administration route: Oral
Indication: Hypothyroidism
Start date: 2009-01-01
Other drugs received by patient: Calcium Carbonate / Ergocalciferol; Albuterol; Theophylline; Zyrtec; Fluticasone Propionate; Alpha Lipoic Acid; Iron; Coenzyme Q10; Lactobacillus Acidophilus; Diflucan
Possible Synthroid side effects in female
Reported by a individual with unspecified qualification from United States on 2012-08-01
Patient: female, weighing 68.5 kg (150.7 pounds)
Reactions: Product Substitution Issue, Laboratory Test Abnormal
Drug(s) suspected as cause:
Synthroid
Possible Synthroid side effects in female
Reported by a consumer/non-health professional from United States on 2012-07-31
Patient: female, weighing 62.2 kg (136.8 pounds)
Reactions: Brain Neoplasm Benign, Weight Increased, Feeling of Despair, Fatigue, Heart Rate Decreased, Alopecia, Dizziness
Drug(s) suspected as cause:
Synthroid
End date: 2012-02-01
Synthroid
Indication: Product Used FOR Unknown Indication
Start date: 2009-02-01
Synthroid
Start date: 2012-02-01
Synthroid
Other drugs received by patient: Reclast
Possible Synthroid side effects in female
Reported by a physician from United States on 2012-07-31
Patient: female
Reactions: Breast Cancer, Constipation, Feeling Cold, Anxiety, Irritability, Fatigue, Hypothyroidism, Fluid Retention
Drug(s) suspected as cause:
Synthroid
Dosage: not reported dose
Indication: Hypothyroidism
Start date: 1987-01-01
Synthroid
Dosage: ^certain pills^ to make 112.5 mcg daily
Synthroid
Dosage: 1-100mcg tablet + 1/2-25 mcg tablet
Synthroid
Dosage: ^certain pills^ to make 112.5 mcg daily
Synthroid
Dosage: ^certain pills^ to make 112.5 mcg daily
Synthroid
Dosage: 1-100mcg tablet + 1/2-25 mcg tablet
Possible Synthroid side effects in female
Reported by a consumer/non-health professional from United States on 2012-07-30
Patient: female
Reactions: Madarosis, Drug Ineffective
Drug(s) suspected as cause:
Latisse
Dosage: 2 gtt, qhs
Administration route: Topical
Indication: Hypotrichosis
Start date: 2011-08-01
Synthroid
Dosage: 112 a?g, qd
Administration route: Oral
Indication: Thyroid Disorder
Start date: 2006-01-01
Possible Synthroid side effects in 47 year old female
Reported by a consumer/non-health professional from United States on 2012-07-27
Patient: 47 year old female, weighing 139.7 kg (307.4 pounds)
Reactions: Drug Dose Omission, Product Quality Issue, Blood Thyroid Stimulating Hormone Increased, Paraesthesia, Muscle Spasms
Drug(s) suspected as cause:
Levothyroxine Sodium
Dosage: 1 tablet daily 2 on sunday po
Administration route: Oral
Indication: Thyroid Hormone Replacement Therapy
Start date: 2012-04-05
End date: 2012-07-25
Levothyroxine Sodium
Dosage: 1 tablet daily 2 on sunday po
Administration route: Oral
Indication: Thyroidectomy
Start date: 2012-04-05
End date: 2012-07-25
Synthroid
Possible Synthroid side effects in female
Reported by a consumer/non-health professional from United States on 2012-07-27
Patient: female, weighing 82.6 kg (181.8 pounds)
Reactions: Uterine Cancer, Poor Quality Drug Administered
Drug(s) suspected as cause:
Synthroid
Other drugs received by patient: Metformin Hydrochloride
Possible Synthroid side effects in 51 year old female
Reported by a consumer/non-health professional from United States on 2012-07-27
Patient: 51 year old female, weighing 68.0 kg (149.6 pounds)
Reactions: Depression
Adverse event resulted in: hospitalization
Drug(s) suspected as cause:
Cogentin
Cymbalta
Klonopin
Seroquel XR
Administration route: Oral
Indication: Bipolar II Disorder
Seroquel XR
Administration route: Oral
Indication: Depression
Synthroid
Wellbutrin
Possible Synthroid side effects in female
Reported by a consumer/non-health professional from United States on 2012-07-27
Patient: female, weighing 110.3 kg (242.7 pounds)
Reactions: Endometriosis, Blood Thyroid Stimulating Hormone Decreased, Uterine Enlargement, Thyroxine Increased, Thinking Abnormal, Hot Flush, Dizziness, Temperature Intolerance, Asthenia, Polycystic Ovaries
Drug(s) suspected as cause:
Synthroid
Indication: Thyroidectomy
Start date: 1971-01-01
End date: 2012-07-17
Synthroid
Start date: 2012-07-17
Other drugs received by patient: Unknown Medications
Possible Synthroid side effects in 62 year old female
Reported by a consumer/non-health professional from United States on 2012-07-26
Patient: 62 year old female
Reactions: Drug Dose Omission, Blood Pressure Abnormal, Memory Impairment
Drug(s) suspected as cause:
Seroquel XR
Administration route: Oral
Synthroid
Possible Synthroid side effects in female
Reported by a consumer/non-health professional from United States on 2012-07-25
Patient: female, weighing 58.0 kg (127.7 pounds)
Reactions: Product Quality Issue, Mucous Stools, Constipation
Drug(s) suspected as cause:
Levoxyl
Dosage: one and a half tablet, 1x/day
Administration route: Oral
Indication: Autoimmune Thyroiditis
Start date: 2011-02-01
End date: 2012-07-01
Levoxyl
Dosage: one and a half tablet, 1x/day
Start date: 2012-04-01
Synthroid
Dosage: unk
Start date: 2011-01-01
End date: 2011-02-01
Possible Synthroid side effects in 38 year old female
Reported by a physician from United Kingdom on 2012-07-25
Patient: 38 year old female
Reactions: Galactorrhoea, Blood Prolactin Increased, Pituitary Tumour Benign
Drug(s) suspected as cause:
Celexa
Indication: Product Used FOR Unknown Indication
Cellcept
Indication: Product Used FOR Unknown Indication
Elavil
Indication: Product Used FOR Unknown Indication
Fosamax
Indication: Product Used FOR Unknown Indication
Neurontin
Indication: Product Used FOR Unknown Indication
Plaquenil
Indication: Product Used FOR Unknown Indication
Prednisone
Indication: Product Used FOR Unknown Indication
Risperidone
Indication: Depression
Start date: 2011-09-01
Synthroid
Indication: Product Used FOR Unknown Indication
Zocor
Indication: Product Used FOR Unknown Indication
Possible Synthroid side effects in female
Reported by a physician from United States on 2012-07-24
Patient: female
Reactions: Thyroid Cancer, Neoplasm Malignant, Muscle Spasms
Drug(s) suspected as cause:
Gleevec
Dosage: 300 mg,
Administration route: Oral
Indication: Chronic Myeloid Leukaemia
Synthroid
Dosage: 88 mg, daily
Administration route: Oral
Indication: Thyroid Disorder
Other drugs received by patient: Ultimate EYE Support; Pantoprazole; Aspirin; Multi-Vitamin; Metamucil-2; Metoprolol Tartrate; Calcium Carbonate
Possible Synthroid side effects in female
Reported by a health professional (non-physician/pharmacist) from United States on 2012-07-24
Patient: female
Reactions: Back Pain, Impaired Work Ability
Drug(s) suspected as cause:
Fluoxetine
Dosage: 20 mg, 1x/day
Administration route: Oral
Neurontin
Dosage: 300 mg, 3x/day
Administration route: Oral
Synthroid
Dosage: 125 ug, 1x/day
Administration route: Oral
Valium
Dosage: 10 mg, 3x/day
Administration route: Oral
Possible Synthroid side effects in female
Reported by a consumer/non-health professional from Brazil on 2012-07-24
Patient: female, weighing 64.0 kg (140.8 pounds)
Reactions: Weight Decreased, Abdominal Pain, Blood Cholesterol Abnormal, Vomiting, Pain, Anaemia, Gastrointestinal Carcinoma, Pyrexia, Blood Triglycerides Abnormal, Endometrial Neoplasm, Abdominal Pain Upper, Rash Macular, Diarrhoea, Visual Impairment, Memory Impairment, Feeling Abnormal
Adverse event resulted in: hospitalization
Drug(s) suspected as cause:
Chemotherapeutics
Dosage: every 20 days
Indication: Gastrointestinal Carcinoma
Chemotherapeutics
Administration route: Oral
Synthroid
Dosage: 1 in 1 day, in the morning
Administration route: Oral
Indication: Hypothyroidism
Synthroid
Dosage: 1 in 1 day, in the morning
Administration route: Oral
Synthroid
Dosage: 1 in 1 day, in the morning
Administration route: Oral
Other drugs received by patient: Alendronate Sodium; Aspirin; Caltrate D; Caltrate D
Possible Synthroid side effects in female
Reported by a physician from United States on 2012-07-23
Patient: female
Reactions: Expired Drug Administered, Atrial Fibrillation, Blood Thyroid Stimulating Hormone Decreased
Adverse event resulted in: hospitalization
Drug(s) suspected as cause:
Synthroid
Dosage: 150 mcg daily
Indication: Product Used FOR Unknown Indication
Synthroid
Dosage: 125 mcg daily
Synthroid
Dosage: 175 mcg daily
Indication: Thyroidectomy
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