Hello,
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Well, this is a tricky situation. If you have easy acess to ER / Urgent care I would recommend getting medical help. 99% chances is that this will NOT evolve into anything serious (Provided you DO NOT take any more Ceftriaxone or Penicillin group medications) . Do take an anti allergy medication like Cetrizine or Allegra once a day for 2-3 days (as early as possible). If you are not going to ER, watch out for danger signs swelling of mouth, lips, throat, breathing difficulty, and dizziness.
You should notify your Doctor about this reaction and should not use Penicillin containing antibiotics without re evaluating the situation.
Hope this helps
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Thank you