Brief Answer:
Yes they can be taken together

Detailed Answer:
Thank you for asking!
Usually synthyroid and actalin do no harm together except iodine of actalin is absorbed less in presence of synthyroid something not to worry about. Actalin is natural herbal supplements and mostly contain of dietary supplement formulated by renowned holistic physician XXXXXXX Brownstein, M.D. to support your optimal thyroid health. This formula contains a strategic blend of 17 nutrients, including iodine, adrenal glandular powder, L-tyrosine, methylsulfonylmethane (MSM), and additional vitamins and minerals.
SO no worries regarding the use together. But you need to be cautious regarding the use of them together for other reasons which is advanced age of yours and narrow therapeutic index of the medicine.
Here are some precautionary measure regarding this medicine use
Avoid undertreatment or overtreatment, which may result in adverse effects

Use caution in cardiovascular disease, HTN, endocrine disorders, osteoporosis, or myxedema

Initiate lower dose in elderly, those with angina pectoris, cardiovascular disease, or in those with severe hypothyroidism

Symptoms may be exacerbated or aggravated with diabetes mellitus and insipidus

Do NOT generally use levothyroxine sodium preparations interchangeably, due to narrow therapeutic index

Check for bioequivalence if switching brands/generics

Synthroid and Unithyroid tabs contain lactose

Not recommended for TSH suppression in patients with thyroid nodules

Levoxyl tabs swell in mouth: take with full glass of water to avoid choking

Avoid use in postmenopausal women >60 years with osteoporosis, cardiovascular disease, or systemic illness

Avoid use in patients with large thyroid nodules or long-standing goiters, or low-normal TSH levels

Long-term therapy decreases bone mineral density; use lowest dose in postmenopausal women and women using suppressive doses.

Stay in touch with your endocrinologist and let him help you with the safest way out. Rest the two mentioned supplements can be taken together.
I hope it helps.Don't forget to close the discussion please.
Regards
S Khan

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