add_disease_treatment_modifier_effect

add_disease_treatment_modifier_effect = {	
	#Treatment length depends on whether the disease has a short or long duration
	#Successful treatments come in two strengths per treatment type, low for diseases with low health penalty and high for diseases with high health penalty
	#Negative treatments only have one strength per treatment type
	#Successful safe treatments remove most of the penalty for low -health diseases but only 1/2-1/4 of penalty for high -health diseases
	#Successful risky/mystic treatments remove almost all of the penalty for all diseases (with plague being the main exception, that penalty is roughly halved)
	#Safe treatment:success

	save_temporary_scope_value_as = {
		name = treatment_result_treatment
		value = flag:$TREATMENT$
	}
	save_temporary_scope_value_as = {
		name = treatment_result_outcome
		value = flag:$OUTCOME$
	}

	#SAFE TREATMENT: SUCCESS
	if = {
		limit = {
			scope:treatment_result_treatment = flag:safe
			scope:treatment_result_outcome = flag:success
		}
		if = {
			limit = {
				has_short_disease_type_trigger = yes
				has_high_health_penalty_disease_type_trigger = yes
			}
			add_character_modifier = { modifier = safe_disease_treatment_success_high_modifier days = disease_treatment_short_duration }
		}
		else_if = {
			limit = {
				has_short_disease_type_trigger = no
				has_high_health_penalty_disease_type_trigger = yes
			}
			add_character_modifier = { modifier = safe_disease_treatment_success_high_modifier days = disease_treatment_long_duration }
		}
		else_if = {
			limit = {
				has_short_disease_type_trigger = yes
				has_high_health_penalty_disease_type_trigger = no
			}
			add_character_modifier = { modifier = safe_disease_treatment_success_low_modifier days = disease_treatment_short_duration }
		}
		else_if = {
			limit = {
				has_short_disease_type_trigger = no
				has_high_health_penalty_disease_type_trigger = no
			}
			add_character_modifier = { modifier = safe_disease_treatment_success_low_modifier days = disease_treatment_long_duration }
		}
	}
	#SAFE TREATMENT: FAILURE
	else_if = {
		limit = {
			scope:treatment_result_treatment = flag:safe
			scope:treatment_result_outcome = flag:failure
		}
		if = {
			limit = { has_short_disease_type_trigger = yes }
			add_character_modifier = { modifier = safe_disease_treatment_failure_modifier days = disease_treatment_short_duration }
		}
		else_if = {
			limit = { has_short_disease_type_trigger = no }
			add_character_modifier = { modifier = safe_disease_treatment_failure_modifier days = disease_treatment_long_duration }
		}
	}
	#RISKY & MYSTIC TREATMENT: CRITICAL SUCCESS
	else_if = {
		limit = {
			OR = {
				scope:treatment_result_treatment = flag:risky
				scope:treatment_result_treatment = flag:mystic #A succcessful mystic treatment shouldn't be noticeable from the outside, so using same modifiers
			}
			scope:treatment_result_outcome = flag:critical_success
		}

		#General cooldown
		add_character_flag = {
			flag = contraction_cooldown_general
			years = 2
		}

		if = {
			limit = { scope:disease_type = flag:consumption }
			remove_trait_force_tooltip = consumption
			add_character_flag = { flag = contraction_cooldown_consumption years = 20 }
		}
		else_if = {
			limit = { scope:disease_type = flag:cancer }
			remove_trait_force_tooltip = cancer
			add_character_flag = { flag = contraction_cooldown_cancer years = 20 }
		}
		else_if = {
			limit = { scope:disease_type = flag:great_pox }
			remove_trait_force_tooltip = great_pox
			add_character_flag = { flag = contraction_cooldown_great_pox years = 20 }
		}
		else_if = {
			limit = { scope:disease_type = flag:gout_ridden }
			remove_trait_force_tooltip = gout_ridden
			add_character_flag = { flag = contraction_cooldown_gout_ridden years = 20 }
		}
		else_if = {
			limit = { scope:disease_type = flag:ill }
			remove_trait_force_tooltip = ill
			#No cooldown, common disease
		}
		else_if = {
			limit = { scope:disease_type = flag:pneumonic }
			remove_trait_force_tooltip = pneumonic
			add_character_flag = { flag = contraction_cooldown_pneumonic years = 20 }
		}
		else_if = {
			limit = { scope:disease_type = flag:typhus }
			remove_trait_force_tooltip = typhus
			add_character_flag = { flag = contraction_cooldown_typhus years = 20 }
		}
		else_if = {
			limit = { scope:disease_type = flag:measles }

As written in game/common/scripted_effects/20_health_effects.txt.