I have under active thyroid and taking levothyroxin. lately my tongue and inside mouth are swelling - is there anything otc which i can take for this?

Need diagnosis: I assume your TSH is normal. Tongue and mouth swelling can be from meds especially ace inhibitors. Are you taking these? Angioneurotic edema is another cause and rarely can indicate lymphoma. Amyloidosis can cause tongue swelling. Suggest you see ENT or dentist. Severe hypothyroidism causes diffuse body swelling, myxedema, so it's possible from not enough levothyroxine.

Swelling: Swelling of oral cavity tissues may indicate allergic response to medication, foods, environmental allergens. See your prescribing physician for evaluation. Your meds may need to be altered.