Do I really need to avoid cotton entirely?

Yes. Once cotton gets wet from sweat or rain, it loses all insulating properties and takes forever to dry, which is dangerous in mountain conditions.

How often should I change my base layers?

In the Himalayas, you will likely wear the same base layer for 3-4 days. Use a merino wool top, which is naturally antimicrobial and resists odors far better than synthetics.

Is it better to buy gear in Kathmandu or bring it from home?

If you want high-end brand name gear, bring it from home. If you are budget-conscious, Kathmandu has plenty of shops to rent or buy decent quality gear, but test zippers and seams thoroughly before leaving the city.

How to Pack Clothing for Himalayan Trekking

Use a three-layer system: a moisture-wicking base, an insulating mid-layer, and a protective shell. Focus on synthetic or merino wool fabrics that dry quickly and layer easily to adapt to rapid weather shifts between 2,000m and 5,000m elevation.

Layering for versatility. Base layer: Always wear merino wool or synthetic. Never pack cotton, as it stays wet and causes hypothermia. Mid-layer: Bring a lightweight fleece for trekking and a heavy down jacket (rated for -10°C/14°F) for evenings at camp or tea houses.
Lower body protection. Pack one pair of lightweight trekking trousers for lower altitudes and one pair of heavier, windproof trousers for high passes. Always carry a pair of thermal leggings to wear under your trousers when temperatures drop below freezing.
Extremity management. Pack two pairs of thick wool trekking socks for movement and one pair of thin clean socks for sleeping. Bring a windproof beanie that covers your ears and a pair of mid-weight gloves with touchscreen compatibility.
Weight distribution. Keep your main pack under 12kg if you have a porter. Pack your shell jacket and mid-layer in your daypack so you can access them within 30 seconds if a sudden mountain squall hits.

Do I really need to avoid cotton entirely?: Yes. Once cotton gets wet from sweat or rain, it loses all insulating properties and takes forever to dry, which is dangerous in mountain conditions.
How often should I change my base layers?: In the Himalayas, you will likely wear the same base layer for 3-4 days. Use a merino wool top, which is naturally antimicrobial and resists odors far better than synthetics.
Is it better to buy gear in Kathmandu or bring it from home?: If you want high-end brand name gear, bring it from home. If you are budget-conscious, Kathmandu has plenty of shops to rent or buy decent quality gear, but test zippers and seams thoroughly before leaving the city.