In some publications it is referred to as two distinct species: P. alcon on wet heathland, moist fen meadows and bogs at low altitude and P. rebeli on dry and subalpine calcareous grasslands. However, genetic research has shown that both have to be considered as being one species.

This species is listed as Least Concern at the European level, as it has been evaluated against all the IUCN criteria and does not meet, nor is it close to meeting (e.g. populations have not been declining by more than 25% in the past 10 years), the thresholds for any category of threat.

In the EU27 countries, a population decline of more than 25% falls within the uncertainty limits for this species' population decline. Therefore, it is classified as Near Threatened within the EU27.

In Central Europe, this species is found from the south of Sweden down to the north of Spain and from France eastwards. 0-1,000 m. It is furthermore present east through Siberia to Mongolia and Altai. The global distribution area of the species is situated both within and outside Europe.

This species always occurs in local, isolated populations and is restricted to (semi-) natural areas. Strong decline in distribution or population size of more than 30% have been reported from Belgium, Germany, Poland, Portugal, Romania, Slovakia, Slovenia, the Netherlands and Ukraine. Decline in distribution or population size of 6-30% have been reported from Austria, Denmark, France, Hungary, Italy, Lithuania, Russia, Spain and Switzerland (data provided by the national partners of Butterfly Conservation Europe).

The Alcon Blue occurs in local, scattered populations, on low-lying wet heathland, on moist fen meadows and bogs and on dry calcareous grasslands. In some publications it is referred to as two distinct species: P. alcon on wet heathland, moist fen meadows and bogs at low altitude and P. rebeli on dry and subalpine calcareous grasslands. However, genetic research has shown that both have to be considered as being one species. The bright, white eggs are easy to find. They are laid on the flowers and sepals of Marsh Gentian (Gentiana pneumonanthe) or Willow Gentian (G. asclepiadea) in the case of the wet P. alcon form, and on Cross Gentian (G. cruciata) by the dry P. rebeli form. At first, the small caterpillars feed on the ovaries of the foodplant, but they pass the later instars in the nests of various Myrmica ants, M. ruginodis, M. scabrinodis and sometimes M. rubra. They hibernate and pupate in the ant nests. The Alcon Blue has one generation a year.
Habitats of the form alcon, adapted to wet localities: humid grasslands and tall herb communities (30%), mesophile grasslands (9%), broad-leaved deciduous forests (9%), heath and scrub (9%), fens, transition mires and springs (7%).
Habitats of the form rebeli, adapted to dry localities: dry calcareous grasslands and steppes (50%), alpine and subalpine grasslands (33%), dry siliceous grasslands (11%), mesophile grasslands (5%).

Changes in agricultural management (improvements like land drainage as well as abandonment) threaten this species in grasslands. Fragmentation and isolation is the most important threat on heathlands, although the species can survive for a long time in small habitat patches. In Western Europe (the Netherlands, Belgium), it is also threatened in nature reserves by habitat degradation of wet heathlands, caused by large-scale lowering of groundwater table and nutrient input.

This species occurs in a number of protected areas across its range. In countries where the species is declining, suitable habitats should be protected and appropriately managed. The effects of conservation actions should be monitored by a Butterfly Monitoring Scheme. Especially egg-counts have proven to be very effective and are possible with a small time-investment.