Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
1
Is any of this happening now?
Call 911
Call emergency services now if you or someone with you has:
A seizure, collapse, or loss of consciousness
Difficulty breathing
Severe confusion or rapidly worsening agitation
Marked muscle rigidity or uncontrollable jerking
A high or rapidly rising temperature
A very fast or irregular heartbeat
Other emergency signs, for anyone
Someone who is struggling to breathe, gasping, choking, or cannot get words out
Someone who has chest pain, tightness or pressure lasting more than a few minutes
Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
Someone who is unconscious, or cannot be woken
Someone who is bleeding heavily and it will not stop with firm pressure
Someone who has had a seizure that will not stop, or does not wake up afterwards
Someone who has lips or skin that look pale, blue, grey or blotchy
Someone who you believe has taken an overdose or swallowed something poisonous
2
Is any of this happening?
Be seen today
Seek urgent medical assessment if new tremor, sweating, diarrhoea, restlessness, muscle twitching, or overactive reflexes develop soon after a medicine change, overdose, or new combination of substances.
Contact a local poison information service immediately after a suspected overdose, even if symptoms have not appeared.
Routine review is not a substitute for urgent care when symptoms are developing.
3
Does any of this apply?
Book an appointment
A routine medication appointment is appropriate if you have no symptoms but are concerned about a possible interaction or want a review before starting an over-the-counter product.
A pharmacist can also check combinations.
The article also says
Do not drive yourself if you are severely unwell.
Bring medicine packets or a medication list if this can be done safely.
Every sign above is quoted from the sofidex article on Serotonin syndrome. If you are not sure, err upward — it is always reasonable to be checked.