The phrase "although dangerous" is correct and usable in written English.
It can be used to introduce a contrasting idea or to acknowledge a risk while presenting a situation or action.
Example: "The hike was beautiful, although dangerous, due to the steep cliffs."
Alternatives: "despite being risky" or "even though it's perilous."
Although dangerous, the process was repeated twice, and proved effective.
Although dangerous, carbon monoxide leakage is a rare occurrence, and local fire department, Con Edison and heating companies will all check for gas leaks on an emergency basis.
Consequently, although Dangerous Minds means well, it's notable for being one of the most egregious examples of Hollywood's "white saviour" trope, in which a white hero ine) will act as the truth, the light and the way for some blighted minority figure(s) (see also: Freedom Writers, The Blind Side, and this year's Kevin Costner mush-fest McFarland USA).
For example, Chrisoula Andreou (2006) argues that, although dangerous environmental destruction is usually analyzed as resulting from interpersonal conflicts of interest, such destruction can flourish even in the absence of such conflicts.
Meeting in person is fun, although dangerous to one's health & fitness.
Although dangerous and illegal, it continues on a secretive yet devastating scale.
"Although not dangerous, it was quite gross.
If so, drugs are an equivalent, although more dangerous, avenue to transcendence.
Although sometimes dangerous to themselves or others, these persons are commonly likable & intelligent.
Thiem now had one in the bank again, this time against a more fragile, although equally dangerous, opponent than Djokovic.
Although his dangerous quest was unsuccessful, the Blackfeet came to him in September 1846, seeking not Christianity but his "great medicine" to help them acquire more enemy scalps and horses.
