High altitude Sickness (HAS) can be life threatening if elevation is gained too rapidly without proper acclimatization. Medical doctors advise against ascending more than 400m a day once above 3000m elevations. Alternatively, one can spend an extra night at 3000m and 3500m before ascending higher.
Over exertion and dehydration contribute to HAS. Drink at least 3-4 liters of water everyday besides tea and coffee which act as diuretics. Watch the health of your companions and porters. Symptoms of HAS are headache, dizziness, trouble in breathing and sleeping, loss of appetite, nausea and general fatigue.  If someone develops HAS symptoms, take the person to lower elevation immediately.

The Langtang-Helambu trails are rocky and slippery after rain or frost. Watch out for falling rocks while crossing landslides but do not stop. Never hike alone. Hiring local guides is strongly recommended on Ganja La (5120m) trek and on Lauribina La (4600m) during winter. Carrying acomprehensive first-aid kit is advisable as there are no medical facilities out of Dhunche. Telephone facilities are available at Singh Gompa and at major settlements in Helambu.