Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
Call emergency services now after a suspected malathion ingestion or if exposure is followed by trouble breathing, heavy secretions, repeated vomiting, confusion, collapse, seizures, or muscle weakness.
Elsewhere, contact your local poison information centre or emergency service.
And for anyone, someone who:
Do not wait for all symptoms to appear.
Contact a poison centre immediately for any suspected exposure, even if symptoms are mild or absent.
In the United States, Poison Control is available at 1-800-222-1222 .
Seek prompt reassessment if symptoms return or new muscle or nerve symptoms develop.
Routine follow-up is appropriate after discharge to review recovery, test results, work safety, and any continuing fatigue or weakness.
The article also says
Move away from airborne pesticide only if this can be done safely.
Do not enter a contaminated enclosed area without proper protective equipment.
Remove contaminated clothing and wash exposed skin, while avoiding contact with the chemical yourself.
Every sign above is quoted from the sofidex article on Malathion poisoning. If you are not sure, err upward — it is always reasonable to be checked.