A Bolivian brewer has come up with an innovative solution for quenching thirst and coping with altitude sickness: coca beer, based on the same leaf used to make cocaine.
Coca has only recently acquired its nefarious reputation: for millennia, people living along the Andes mountains have chewed coca leaves. The juice from the leaves has a mild stimulant effect, easing stomach pain and helping people from the lowlands cope with altitude sickness, known locally as soroche.
Visitors to high mountain cities like La Paz - located 3600m above sea level - often rest and drink coca tea to deal with soroche. Now there is another option.
"As good Germans we love beer," said Hamburg native Malina, who sipped her beer along with her travelling companion Timo. The friends are students in their late 20s travelling across South America.
"There are many types in Germany, but this coca beer is good because here in La Paz it helps us handle altitude sickness," she said.
She compared the taste to Hefeweizen, a full-bodied unfiltered wheat beer from Bavaria.
Her companion agreed. "This is a very good beer, just like that from southern Germany, but not as heavy - and the alcohol gets to you faster," he said.
The beer in question is called Ch'ama, or "Strength" in the Aymara language of the Lake Titicaca area natives. It is made from malt, yeast, hops and soaked coca leaves, with no additives or preservatives.
The beer is in demand among tourists "who want to try something new", said Alejandra Orihuela, owner of a bar named K'umara ("Healthy" in Aymara).
She said that a group of German and American tourists liked it so much they came by several times a day for their coca beer, "as if it were breakfast and lunch".
Coca beer has been produced since 2011 by Cerveceria Vicos, a brewery based in the southeastern city of Sucre.
"This is a highly fermented white beer with five per cent alcohol content, unfiltered, unpasteurised, and has the moderate aroma, colour and flavour of coca leaf and hops," Vicos owner and manager Victor Escobar said.
He claims the beverage is an "energising" tonic.
To produce Ch'ama coca beer, Escobar first soaks coca leaves in water, then adds malted barley and hops until the mix reaches its proper consistency. After a 20-day fermentation process, the concoction is bottled.
Cerveceria Vicos is a small brewery, producing 10 hectolitres of coca beer a day.
Retail prices vary, but Ch'ama beer sells for up to $A3.55 per bottle. It is sold in Bolivia and towns just across the borders with Peru and Chile.
But what about coca leaves and that nasty illegal drug cocaine?
Cocaine is also produced by soaking coca leaves, but instead of water, drug dealers use kerosene, petrol and chemicals like hydrochloric acid and ammonia. A solution from the leaves is then filtered, refined and crystallised.
Bolivia opposes the use of cocaine, but deplores the demonisation of the coca plant.
President Evo Morales, a former head of the country's coca growers union, is a strong supporter of finding legal ways of using the plant and of rehabilitating its reputation.
Bolivia withdrew from the Vienna-based UN Convention on Narcotic Drugs last year, angry that the coca leaf was labelled an illegal drug. It was readmitted in January after winning an opt-out allowing its population to keep legally chewing the leaves.
The coca bush grows exclusively in the eastern slopes of the Andes.
Bolivia is the world's third largest producer of coca leaves after Peru and Colombia.